Epidemiology module of practical skills for MBBS studentnihfw.org/Doc/Public Health conclave/draft...

KNOWLEDGE BASED COMPETENCIES AND METHODS

COMPETENCIES METHODS

1.1. Listing of epidemiological techniques and methodsListing of epidemiological techniques and methods Lecture, Review of Research Articles .Lecture, Review of Research Articles .

2.2. Describing application of these methods to communicable and non-Describing application of these methods to communicable and non-communicable diseases in community and hospital situationcommunicable diseases in community and hospital situation

Project work in Community and Hospital.Project work in Community and Hospital.

3.3. Apply biostatistical method and techniqueApply biostatistical method and technique Lecture, Practical and Project work.Lecture, Practical and Project work.

4.4. Deciding when there is epidemicDeciding when there is epidemic visit to District health office and record sectionvisit to District health office and record section

5.5. Method of surveillanceMethod of surveillance Lecture and visit to PHCLecture and visit to PHC

6.6. Steps of investigation of an epidemicSteps of investigation of an epidemic Case StudyCase Study

7.7. Steps Of Designing any Research activitySteps Of Designing any Research activity Project work and lectureProject work and lecture

SKILL BASED COMPETENCIES AND METHODS

1.1. Use epidemiology as a scientific tool to make rational decision Use epidemiology as a scientific tool to make rational decision relevant to community & individual patient interventionrelevant to community & individual patient intervention

Case Study And Project WorkCase Study And Project Work

2.2. Collect , analyse , interpret & present simple community & hospital Collect , analyse , interpret & present simple community & hospital based data.based data.

Project WorkProject Work

3.3. Investigation of epidemic.Investigation of epidemic. Case StudyCase Study

4.4. Designing study to test hypothesisDesigning study to test hypothesis Lecture and Case StudyLecture and Case Study

5.5. Applying appropriate statistical method to test the significance of Applying appropriate statistical method to test the significance of associationassociation

Project workProject work

6.6. Writing research article /report.Writing research article /report. Project work, Article reviewProject work, Article review

7.7. Method for reviewing research article.Method for reviewing research article. Journal presentation and discussionJournal presentation and discussion

8.8. To keep track of the disease in the community & to decide the action To keep track of the disease in the community & to decide the action if warranted at PHC level.if warranted at PHC level.

Lecture and Case studyLecture and Case study

AN EXAMPLE… INVESTIGATION OF AN OUT BREAK.

1.1. Defining EpidemicDefining Epidemic Lecture ,Review of Research articlesLecture ,Review of Research articles

2.2. Listing types of epidemicListing types of epidemic Project work in community and hospital Project work in community and hospital

3.3. Deciding when there is epidemicDeciding when there is epidemic visit to district health office and record sectionvisit to district health office and record section

4.4. Method of surviellenceMethod of surviellence Lecture and visit to PHCLecture and visit to PHC

5.5. Steps of investigation of an epidemic Steps of investigation of an epidemic Case Study Case Study

6.6. Prevalence and incidence of endemic diseasesPrevalence and incidence of endemic diseases Visit to PHCVisit to PHC

7.7. Demography of the area of concernDemography of the area of concern LectureLecture

8.8. Reference laboratories available for Virus/Bacterial CultureReference laboratories available for Virus/Bacterial Culture Visit to PHC/CHC/District hospitalVisit to PHC/CHC/District hospital

9.9. Collect , analyse , interpret & present data related to out break Collect , analyse , interpret & present data related to out break Project WorkProject Work

10.10. Applying appropriate statistical method to test the significance of Applying appropriate statistical method to test the significance of association.association.

Project WorkProject Work

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METHODS FOR EPIDEMIOLOGY & RESEARCH

CONTENTS

SECTIONS Topics SECTION - A Epidemiological methods and techniques

SECTION - B Surveillance- methods use and example

SECTION - C Outbreak investigation

SECTION - D Designing a research activity

ANNEXURES OUTBREAK INVESTIGATION

(Trigger & Response Mechanisms)In IDSP

IDSP forms and surveillance guidelines

Writing reports/ articles Reviewing a research article Exercise on understanding

community Exercise Community Involvement

and Communication Exercise on supportive supervision

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SECTION – A

Epidemiological methods and techniques

Epidemiology module of practical skills

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Learning Objective

The student should be able to know the relevance & importance of applying epidemiological skills to bring out effectiveness as a basic doctor in Rural e.g. PHC& other urban settings .

Student should be able to understand the implication of epidemiological principles in various National Health Programmes.

Use epidemiology as a scientific tool to make rational decision relevant to community & individual patient intervention

When should s are going to field visits he/she should be able to do Measurement of morbidity , mortality , Incidence & prevalence from existing data of recent outbreaks in community provided by the health centre authorities.

Epidemiology Defined

"The study of the distribution and determinants of health-related states in specified populations, and the application of this study to control health problems."

A look at the key words will help illuminate the meaning:

Study—Epidemiology is the basic science of public health. It's a highly quantitative discipline based on principles of statistics and research methodologies.

Distribution—Epidemiologists study the distribution of frequencies and patterns of health events within groups in a population. To do this, they use descriptive epidemiology, which characterizes health events in terms of time, place, and person.

Determinants—Epidemiologists also attempt to search for causes or factors that are associated with increased risk or probability of disease. This type of epidemiology, where we move from questions of "who," "what," "where," and "when" and start trying to answer "how" and "why," is referred to as analytical epidemiology.

Health-related states—Although infectious diseases were clearly the focus of much of the early epidemiological work, this is no longer true. Epidemiology as it is practiced today is applied to the whole spectrum of health-related events, which includes chronic disease, environmental problems, behavioral problems, and injuries in addition to infectious disease.

Populations—One of the most important distinguishing characteristics of epidemiology is that it deals with groups of people rather than with individual patients.

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Control—Finally, although epidemiology can be used simply as an analytical tool for studying diseases and their determinants, it serves a more active role. Epidemiological data steers public health decision making and aids in developing and evaluating interventions to control and prevent health problems. This is the primary function of applied, or field, epidemiology.

A comparison between the practice of public health and the more familiar practice of health care helps in describing epidemiology.

First, where health care practitioners collect data on an individual patient by taking a medical history and conducting a physical exam, epidemiologists collect data about an entire population through surveillance systems or descriptive epidemiological studies.

The health care practitioner uses his or her data to make a differential diagnosis. The epidemiologist's data is used to generate hypotheses about the relationships between exposure and disease.

Both disciplines then test the hypotheses, the health care practitioner by conducting additional diagnostic studies or tests, the epidemiologist by conducting analytical studies such as cohort or case-control studies.

The final step is to take action. The health care practitioner prescribes medical treatment, and the epidemiologist, some form of community intervention to end the health problem and prevent its recurrence.

One succinct way to sum up the task of epidemiologists is to say that they "count things." Basically, epidemiologists count cases of disease or injury, define the affected population, and then compute rates of disease or injury in that population. Then they compare these rates with those found in other populations and make inferences regarding the patterns of disease to determine whether a problem exists,. For example, in the hepatitis B example earlier, you might ask: Is the rate of disease among people with no know risk factors greater than we would expect? Is the pattern or distribution of the cases suspicious? Once a problem has been identified, the data are used to determine the cause of the health problem; the modes of transmission; any factors that are related to susceptibility, exposure, or risk; and any potential environmental determinants.

For this students should be aware of basics of epidemiology in terms of

I. MEASUREMENT OF FREQUENCIES

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II. CONCEPT OF NUMERATOR AND DENOMINATOR

III. MEASURES OF CENTRAL TENDENCY

IV. MEASURES OF DISPERSION

V. MEASUREMENTS OF MORBIDITY

VI. MEASUREMENT OF MORTALITY

VII. MEASUREMENTS OF FERTILITY

VIII. MEASUREMENTS OF DISABILITY

I. MEASUREMENTS OF FREQUENCIES :

Rate, Ratio, and Proportions

i. Rate: The rate is the occurrence of a particular event in a population during a given time period. Example: Crude Death Rate No. of deaths in one year

Death rate= _____________________ X 1000 Mid- year populatione.g., 24 deaths occurred in a village having mid-year population of 4000

Calculation:Death rate in that village = 24X1000/4000=6 per 1000 populationNote: Rate comprises the following elements- numerator, denominator, time specification and multiplier. The time dimension is usually a calendar year. The rate is expressed per 1000 or some other round figure selected according to the convenience or convention, to avoid fractions.Types

a. Crude Rates: birth and death rates. These are un-standardized rates. b. Specific rates: disease specific, age and sex specific, time specific.c. Standardized rates: these are obtained by direct or indirect method of standardization or adjustment e.g. age and sex standardized rates.

ii. Ratio: It expresses a relation in size between two random quantities. The numerator is not a component of denominator. The numerator and denominator may involve an interval of time or may be

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instantaneous in time. Broadly, ratio is the result of dividing one quantity by another. It is expressed in the form of x: y, e.g. sex ratio, doctor-population ratio, child-woman ratio, etc. Say sex ratio is 933: 1000.

iii. Proportion: is a ratio, which indicates the relation in magnitude, of a part to the whole. The numerator is always included in the denominator. It is usually expressed in percentage, e.g. percent of under five children suffering from malnutrition of the total under five populations. Say a proportion of 60% of the under five children is suffering from malnutrition.

Exercises and Solutions

Rates and Percent DistributionsExercise AThe following are data for two counties:

Recall the formulas for the crude birth and fertility rates:

For each of the counties, calculate the following:1. the crude birth rate2. the crude fertility rate3. the fertility rate for adolescents aged 10-174. the percent of total births to adolescents aged 10-17

Do either County X or County Y have an excess of adolescent births? Which county is in more need of programs targeted at the adolescent population?

SOLUTION: Rates and Percent Distributions

Solution for Exercise A

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County Y has a higher % births to adolescents than County X, but a lower adolescent fertility rate. This is because the adult women in County Y have a lower fertility rate than the adult women in County X resulting in the lower overall birth and fertility rates seen in the above table for County Y. The elevated %births to adolescents in County Y compared to County X, therefore, is due to these differences in the rates for the adult women.

The % births to adolescents are not a rate because adult women who are no longer at risk of delivering in their teen years are included in the denominator. It can be argued that the adolescent fertility rates are a “fairer" comparison of the two counties since they are based solely on the experience of their adolescent populations, unrelated to the experience of other women. On the other hand, some might argue for using% births to adolescents precisely because it reflects the experience of teenage women in relation to the overall fertility behaviour in their communities.

Defining excess adolescent fertility must be based on a community standard. It may be that any adolescent childbearing is considered an excess, or this may be determined in relation to a state or National average or goal.

II. CONCEPT OF NUMERATOR AND DENOMINATOR:

For calculation of rate, ratio or proportion proper understanding of the Concept of Numerator and Denominator is very important.a. Numerator: Numerator refers to the number of times an event (e.g. number of birth) has occurred in a population, during a specified time period. b. Denominator: Numerator has little meaning unless it is related to the denominator. The epidemiologist has to choose an appropriate denominator while calculating a rate. It may be related to: (I) population (II) the total events.(I) Denominator related to the population:

(i) Mid year population: Because the population size changes daily due to births, deaths and migration, the mid year population is commonly chosen as a denominator. The population as on 1st July is mid-year population.

(ii) Population at risk: It is important to note that the calculation of measures of disease frequency depends on correct estimates of the numbers of people under consideration. Ideally, these figures should include only those people who are potentially susceptible to

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the disease studied. For instance, men should not be included in denominator for the carcinoma of cervix.Part of population, which is susceptible to a disease is called the population at risk, e.g., Occupational injuries occur only among working people so the population at risk is the workforce.

(iii) Person – time: In some epidemiological studies (e.g. cohort studies), person may enter into the study at different times. Consequently, they are under observation for varying time period. In such case, the denominator is a combination of person and time. The most frequently used person time is person- years. Some times this may be person months, person weeks or man- hours. For example, if 10 persons were observed in the study for 10 years, person time would be 100 person years of observation. The same figure would be derived if 100 persons were under observation for one year. These denominators have the advantage of summarizing the experience of persons with different duration of observation or exposure.

(iv) Sub groups of the population: the denominator may be subgroups of population e.g. under-five, female, doctors, etc.

(II) Denominator related to total events: In some instances, the denominator may be related to total events instead of the total population, as in the case of infant mortality rate the denominator is total number of live births.

III. MEASURES OF CENTRAL TENDENCY We need to workout averages for large number of values to make some sense. It gives the mental picture of the central value. There are several kinds of average, of which the commonly used are arithmetic mean, mode and median. Averages are measures of central value, therefore they locate the center or mid point of a distributions.

(a) Mean: To obtain the mean the individual observations are added together, and then divided by the number of observations.

(b) Mode: The mode is the most commonly occurring value in a distribution of data.

(c) Median: To obtain the median, the data is first arranged in a descending and ascending order the value of middle observation is located, which is called median.

EXERCISE

Calculate mean, mode, and median for hemoglobin values of 20 pregnant women.

12, 10, 8, 9, 12, 10, 7, 9, 7, 10, 11, 8, 12, 7, 8, 13, 11, 9, 10, 11, 7

Mean:

Median:

Mode:

IV MEASURES OF DISPERSION

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(a) Percentile: Sometime one has to locate other points in the range. This can be done with the help of percentile. Just as the median divides the subjects in two equal groups each with nearly n/2 subjects, the percentiles divide the subjects in 100 equal parts. Each part is containing n/100 subjects. If n= 400, each part will have 4 subjects. The parts are identified by 99 cut points of the measurements under consideration. Consider weight to nearest Kg. of 2 yr old 35 boys:

10, 12, 9, 11, 10, 12, 12, 13, 8, 9 13, 14, 13, 8, 9, 11, 11, 10, 12, 13, 9, 12, 10, 11, 14, 9, 12, 12, 13, 12, 9 13, 10, 11, 10,

For example 20ths percentile of weight is that value below which are 20% children, for n=35, then 20% of children mean 7 children. The procedure is to arrange their weights in ascending order and pick up the seventh value. When arranged in ascending order, there weights in Kg. are:

8, 8, 9, 9, 9, 9, 9, 9, 10, 10, 10, 10, 10, 10, 11, 11, 11, 11, 11, 12, 12, 12, 13, 12, 12, 12, 13, 13, 13, 13, 13, 13, 13, 14, 14

The seventh value is 9 kg. This is the 20 th percentile of weight of 2 yr old boys as far as these data are concerned. Similarly we can find out given percentile by adopting the above procedure. It can be determined by the formula [kth percentile = (k X n/100)].

(b) Deciles, Quartiles and Tertiles:

Deciles divide the group of subject in to 10 equal parts. Quartiles in to four equal parts and tertiles into three equal parts. Tertiles are often used to divide the subjects into those with low, medium and high values.

V MEASUREMENTS OF MORBIDITY

Morbidity data should be accurately and completely collected and transformed into various rates to make the understanding of magnitude of the health related event meaningful.

i. Incidence Rate (IR):

It is the number of new events that occurs in a defined time period in a geographical area. The denominator is the population at risk for that event during that period. The most accurate way of calculating incidence rate is person-time incidence rate. Each person in the study population contributes one-person year to the denominator for each year of observations before disease develops or the person is lost to follow-up.

No. of people who get a disease in a specified period

IR =______________________________________________X 1000

Sum of the length of time during which each person in the

population is at risk.

The incidence rate takes into account the variable time periods during which individuals are disease free and thus at risk of developing the disease. Since it may not be possible to measure disease free periods precisely, the denominator is often calculated approximately by multiplying

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the average size of the study population by the length of the study period. This is reasonably accurate if the size of the population is stable and I.R. is low. For example, in a sub-center with population of 5000 there are 5 new cases of tuberculosis occurred during one year. For this disease the whole population is at risk of tuberculosis, hence the incidence rate of tuberculosis would be 1 per 1000.

EXERCISE

In order to measure the quantum of sickness in children under 5 years of age , a astudy was conducted among 153 children from May 2004 to April 2005 in Urban area . The five leading cause of illness of number of person ill and spels of illness is as follows ;

Disease No of children ill No. of spell

Common cold 103 169

Diarrhea 62 132

Boils 60 73

Fever 37 42

Conjuctivities 31 37

Calculate

i Incidence rate(person) for each of the leading cause?

ii Incidence rates (spells) for each of the leading cuses?

iii Spells of illness for each disease for each sick child?

Special Incidence Rates:

(a) Attack rate: The attack rate is defined as number of new cases of a specified disease during a specified time interval per 100 populations at risk during the same time interval. An attack rate is used only when the population is exposed to risk for a limited period of time such as during an epidemic.

Formula:

Number of new cases of a specified disease

during a specified time interval

Attack rate = ------------------------------------------------------------ X100

Total population at risk during the same time interval

(b) Secondary attack rate (SAR): is defined as the number of exposed persons developing the disease within the range of incubation period following exposure to a primary case.

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Formula:

Number of exposed persons developing the disease

within the range of incubation period

SAR = ------------------------------------------------------------------X 100

Total number of exposed/ susceptible contacts

The denominator consists of all persons who are exposed to case. More specifically, the denominator may be restricted only to susceptible contacts. The primary case is excluded from both numerator and denominator.

Example: Suppose there is a family of 6 consisting of 2 parents (already immune) and 4 children who are susceptible to a specific disease, say measles. There is a primary case and within a short time 2 secondary cases among the remaining children. The secondary attack rate is 2/3 or 66.6%.

Exercise 1 – During an eight hour work shift at a factory , 30 employee visited the company physician with the complaints of nausea , vomiting headaches & dizziness.

Q.. If 600 hundred person worked in the factory what is the attack rate of the disease ?

Exercise 2

There was an out break of Typhoid Fever in Pondicherry . Few cases occurred in JIPMER campus and some from various part of the town . Secondary cases with in 30 days of onset were also reported .Data are given below -----

Typhoid fever in household pondicherry secondary cases in houses with two types of sanitary facilities .

Household with Privy & Well Houses with public water supply &

sever system

Age in

years

No. of contact

exposed to

primary cases

No. of

sec.cases

Attack

rate

No. of

contact

exposed to

primary

cases

No of

sec.cases

Attack

rate

0-4 173 41 143 9

5-14 196 37 216 10

15&above 245 24 361 14

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Total 614 102 720 33

Q1 – Calculate the secondary attack rate in each category.

Q2- What inference do you draw from this result?

ii. Prevalence: The total number of all individuals who have an attribute or disease at a particular time or during a particular period divided by the populations at risk of having the attribute or disease at this point of time or midway through the period. Although referred as rate, prevalence is really a ratio.

Types of Prevalence

a) Point Prevalence: The data have been collected for one point of time. The point in, point prevalence may for all practical purposes consist of a day, several days or even a few weeks depending upon the time taken to examine the population sample.

b) Period Prevalence: It measures the frequency of all current cases (Old & New) existing during a defined period of time (e.g. annual prevalence) expressed in relation to a defined population. It includes cases arising before but extending into or through the year as well as those cases arising during the year.

No. of existing cases (old & new) of a specified disease

During a given year (period of time interval)

Prevalence = -------------------------------------------------------------X1000

Estimated mid year (interval) population

iii. Relationship of Incidence with Prevalence

Prevalence depends upon two factors- the incidence and duration of illness

P = I X D

P= Incidence X mean Duration

Prevalence vs. IncidenceExercise B

In June, 1995, at the end of their senior year, the following observations were made concerning smoking in a population of 110 graduating seniors. The enrolment for this cohort from 9th to 12th grade was as follows:

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9th Sept. 1991 16010th Sept. 1992 14011th Sept. 1993 12012th Sept. 1994 110

The seniors were asked the following question. “At any time while you were in high school (Sept. ‘91 -June ‘95), did you smoke at least one pack of cigarettes a week? If yes, when did you start and for how long did you smoke?” Of the 110 graduating seniors surveyed, 20 reported having smoked at some time during high school. The following table shows the data for these 20 students:

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Using the data above, answer the following questions:1. From Sept. 1993 - Aug. 31, 1994 what was the incidence rate of smoking?

2. What was the prevalence of smoking at the time of the survey in June, 1995?

3. The survey was given to the 110 graduating seniors. How valid are the results of the survey as estimates of smoking incidence and prevalence for the high school age adolescents in this community?

Prevalence vs. IncidenceSolution for Exercise B1. Students #4, #9, and #16 begin smoking during this time, and ten other students were already smoker sand therefore not at risk for becoming smokers, so the incidence rate is 3 / (110-10) or 3.0 %.2. Nine students were smoking at the time they graduated high school, for a prevalence rate of 9 / 110 or8.2 %.3. If smoking behaviour among graduating seniors is the same as that for students who dropped out, then the results are good estimates. If smoking status is related to drop out status, then the results may be over or underestimates depending on whether those who finish high school are more or less likely to smoke than those who do not.

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Incidence and PrevalenceExercise CThe County Y Head Start Program enrolled 500 children in the Fall of 1995. All of these children were screened for vision problems at the beginning of the year and 50 were found to have vision problems.

When the same 500 children are screened again in the Fall of 1996, 65 are found to have vision problems.

1. What was the prevalence of vision problems in County Y’s Head Start program in 1995?2. What was the prevalence of vision problems in County Y’s Head Start program in 1996?3. What is the risk of developing vision problems between the Fall of 1995 and the Fall of 1996 in this group of Head Start children?

Solution for Exercise C1. 50/500 = 10%2. 65/500 = 13%3. Risk means incidence; # of new cases/population at risk = 15 = 3.3% 450

Exercise DThe Hospital X Emergency Room in Community A recorded 120 asthma cases during 1995 out of a total of 1450 individual children seen. The state Children with Special Health Care Needs (CSHCN) program was interested in determining if these numbers meant an increased risk of a child developing asthma in Community A or a possible decrease in the effectiveness of the medication taken by asthmatic children in Community A. In 1996 they asked the hospital to track the number of first time asthma diagnoses admitted to the ER versus those asthma cases who visited the ER but had been previously diagnosed as having asthma.In 1996 out of 1370 children seen in the ER, there were 130 asthma cases: 42 were new cases, 88 had been previously diagnosed prior to the ER visit.

1. What was the risk of having asthma in 1995 for children in Community A seeking ER care at Hospital X?

2. What was the prevalence of childhood asthma in 1995 in the ER at Hospital X in Community A?

3. What was the prevalence of childhood asthma in 1996 in the ER at Hospital X in Community A?

4. Can the state CSHCN program answer its question?

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5. Does knowing the incidence of childhood asthma diagnoses in the ER at Hospital X in Community Ain 1996 help? What is the incidence?

6. What else is needed to answer the CSHCN program’s question?

Incidence and PrevalenceSolution for Exercise D

1. Risk refers to incidence data. Since there is no information about new cases for 1995, this question cannot be answered.

2. 120/1450 = 8.3%

3. 130/1370 = 9.5%

4. No, these two prevalence estimates do not provide any information about the risk of developing asthma among children in Community A.

5. Knowing the incidence rate helps somewhat but does not tell the entire story as children seeking care for their asthma in the ER are not representative of the entire population of children with asthma in Community A. Incidence rate: 42/1282 =3.3%

6. It would be helpful to have baseline information on the incidence rate of childhood asthma diagnoses in the ER at Hospital X in Community A. Short of obtaining information from population based child health surveys over time, it would also be important to obtain data from primary care physicians in the community, other community hospitals, from the schools, and possibly from the pharmacists in the community. In addition, it might be helpful to compare Community A's data to data from similar communities

Example: If incidence is 10 cases / 1000 people per year and mean duration of disease is 5 years, then

Prevalence = 10 X 5 = 50 / 1000 population.

EXERCISE:In a population of 1000, following are the details of cases of tuberculosis. Calculate incidence, point prevalence (as on 1st July) and period prevalence for 2001 and comment on it. Case No Detected on Died / Cured on

1 Jan 12, 1999 March 13, 2001

2 Feb 13, 1999 Dec 18, 2000

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3 April 29, 1999 Not cured upto 31 Dec 2003

4 Oct 23 1999 Sept 23, 2002

5 Feb 12, 2000 Oct 30, 2001

6 April 1, 2000 Sept 21, 2001

7 June 23, 2000 April 1, 2002

8 Feb 24, 2001 May 23, 2002

9 July 11, 2001 July 12, 2003

10 Aug 15, 2001 April 11, 2002

11 Sept 23, 2001 May 9, 2003

12 Nov 21, 2001 Not cured upto 31 Dec 2003

13 April 12, 2002 July 12, 2003

14 June 13, 2002 Sept 23, 2003

15 Oct 3, 2002 Not cured upto 31 Dec 2003

16 Dec 12, 2002 Dec 23, 2003

17 Dec 16, 2002 Sept 1, 2003

18 Feb 12, 2003 Not cured upto 31 Dec 2003

19 Sept 1, 2003 Not cured upto 31 Dec 2003

20 Oct 11, 2003 Not cured upto 31 Dec 2003

VI MEASUREMENTS OF MORTALITY

i Crude Death Rate

It is defined as “the number of deaths (from all causes) per 1000 estimated mid year population in

one year, in a defined geographical area.

No. of deaths during the year

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Crude Death Rate = ------------------------------------x 1000

Mid year population

ii Specific Death Rates: can be specific to age, sex, occupation, diseases, etc.

Disease Specific Mortality:

No. of deaths from specific disease

during a calendar year

Disease Specific = ------------------------------------------------ X 1000

Mortality Rate Mid year population

Example: In a village with population of 5000 there are 5 deaths due to tuberculosis occurred in a

year. Death rate due to tuberculosis would be 1 per 1000.

Child Mortality

Still Birth Ratio: Defined as “ Death of foetuses weighing 1000 gm (this is equivalent to 28 weeks of

gestations) or more occurring during one year in every 1000 live births.

Foetal deaths weighing 1000gm or more at birth

Still Birth=------------------------------------------------------------- X 1000

Ratio Total no of live births

Still Birth Rate: Still Birth Rate is defined as number of deaths of foetuses weighing 1000gm or

more occurring during 1 year per 1000 total births (live + still births).

Still Foetal death weighing 1000gm or more at birth

Birth = --------------------------------------------------------------- X 1000

Rate Total (live + still) births weighing 1000gm or more at birth

Neonatal Mortality Rate (NMR): NMR is defined as the number of neonatal deaths under 28 days

of age in a given year per 1000 live births in that year

No of death of children under 28 days of age in a year

NMR=------------------------------------------------------------------- x1000

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Total live births in the same year

Post-neonatal Mortality Rate: It is defined as the ratio of post neonatal deaths (28 days to under

one year) in a given year to the total number of live births in the same year, usually expressed as a

rate per 1000.

No. of deaths of children between 28 days

and one year of age in a given year

PNMR = ------------------------------------------------------- X 1000

Total live births in the same year

Peri-natal Mortality Rate (PMR): It is defined as number of foetal deaths (28 weeks gestations &

more) + early neonatal deaths (Ist week) in one year per 1000 live births in the same year

Number of foetal deaths (28 weeks gestations & more)

+ Early neonatal deaths (Ist week) in one year

PMR=-------------------------------------------------------------------X 1000

Live births in the same year

Infant Mortality Rate (IMR): Defined as the ratio of infant deaths in a given year to the total

number of live birth in the same year, usually expressed as a rate per 1000 live births.

No. of deaths of children less than 1 year of age in a year

IMR=----------------------------------------------------------------------X 1000

No. of live births in the same year

Under 5 Mortality Rate (U5MR): It is defined as annual number of deaths of children under 5 years

of age expressed as a rate per 1000 live births.

No of deaths of children <5 years of age in a given Year

U5MR = ---------------------------------------------------------------X1000

No. of live births in the same year

Maternal Mortality Rate (MMR): Total No. of female deaths due to complications of pregnancy

per 1000 births (live + still) and abortions.

Number of deaths of the females due to complications of

pregnancy or within 42 days from puerperal causes in an

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area during a given year x 1000

MMR = ----------------------------------------------------------------------

Total No. of pregnancies terminated as birth (still or live)

+ abortions in the same area and year

Number of deaths of the females due to complications of pregnancy or within 42 days from puerperal causes in an area during a given yearMaternal=---------------------------------------------------------------x1000Mortality Total No. of live births in the same area & yearRatio

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Exercise:

Consider following data for a village.Total population -2500Population of infants-70And numbers of still births (10) + live (80) in one year. Total births are 90Infant deaths -10 (neonatal =2, post-neonatal=8)Under five deaths-14Maternal deaths -2Total deaths in one year-25

Contd.

Exercise

Calculate the following rates /ratios based on the data given above and compare with national data.1. Still birth ratio2. Still birth rate3. Perinatal mortality 4. Neonatal mortality rate5. Infant mortality rate6. Under five mortality rate 7. Maternal mortality rate 8. Maternal mortality ratio 9. Crude death rate10. Post neonatal mortality rate

Case Fatality Rate: Case fatality rate represents the killing power of a disease. It is simply the ratio of deaths to cases. The time interval is not specified. Case fatality rate is typically used in acute infectious diseases (e.g. food poisoning, cholera, and measles). Its usefulness for chronic diseases is limited because the period from onset to death is long and variable. The case fatality rate for the same disease may vary in different epidemics because of changes in the agent, host and environmental factors. Case fatality is closely related to virulence.

Total No of deaths due to a particular disease

Case fatality rate=------------------------------------------------------ X 100

Total no of cases due to the same disease

Adjusted (Standardized) Rate: If we want to compare the death rate of two populations with different age composition, the crude death rate is not the right yardstick. This is because rates are only comparable if the populations upon which they are based are comparable. And it is cumbersome to use a series of age specific death rates. The answer is “age adjustment” or “age standardization”, which removes the confounding effect of different age structure and yields a single standardized or adjusted rate, by which the mortality experience can be compared directly. The adjustment can be made not only for age but also for sex, race, parity, etc.

VII MEASUREMENTS OF FERTILITY

i Crude Birth Rate: Defined as the number of live births per 1000 estimated mid year population in a given year.

No of live births during the year

Birth Rate = ---------------------------------------X 1000

Estimated mid year population

ii Total Fertility Rate (TFR): It represents the average number of children a woman would have if she were to pass through her reproductive years (15-45 years) bearing children at the same rates as the woman now in each age group. It is computed by summing the age specific rates for all ages. If 5 years age groups (intervals) are used, the sum of the rates is multiplied by 5. This measure gives the approximate magnitude of completed family size. In India TFR in the year 2003 is estimated to be 2.8, i.e., on an average one woman gives 2.8 live births during her reproductive period.

Example: Computation of the specific fertility rate and total fertility rate from the data given below:Age group (Years) No. of women

(A)

No. of live births

(B)

15-19 25000 800

20-24 20000 2400

25-29 19000 2000

22

30-34 16000 1500

35-39 14000 120

40-44 6000 10

Total 100000 6830

Computation of age specific fertility rate:

Step I: C=B/AX1000

For age 15-19 years = 800/25000x1000=32.00

For age 20-24 years = 2400/20000x1000=120.00

For age 25-29 years = 2000/19000x1000=105.26

For age 30-34 years = 1500/16000x1000=93.75

For age 35-39 years = 120/14000x1000=8.57

For age 40-44 years = 10/6000x1000 = 1.67

Step II: Total Births=CX5

Exact age (years) SFRx5 Total births per

1000 females aged

15 to 44 by stated

ages

15-19 32x5=160 160

20-24 120x5=600 760

25-29 105.26x5=526.30 1286.30

30-34 93.75x5=468.75 1755.05

35-39 08.57x5=42.85 1797.90

40-44 01.67x5=8.35 1806.25

Total fertility rate (TFR) = sum of S.F.R./1000

= 1806.25/1000

= 1.8

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iii Net Reproduction Rate (NRR): NRR is defined as the number of daughters a new born girl will bear during her life time assuming fixed age specific fertility and mortality rate. NRR is a demographic indicator. NRR of 1 is equivalent to attaining approximately the 2-child norm. If the NRR is less than 1 then the reproductive performance of the population is said to be below replacement level.

The Demographers are of the view that the goal of NRR 1 can be achieved only if effective couple protection rate is above 60%.

Example:

Age group Female

population

Female

births

Specific

fertility rate

per women

(S.F.R.)

Survival rate

(S)

S.F.R. x S

15-19 1600000 19000 0.0119 0.921 0.0110

20-24 10,00000 70200 0.0702 0.901 0.0633

25-29 16,8500 90600 0.0538 0.885 0.0476

30-34 17,30000 62400 0.0361 0.862 0.0311

35-39 1,72000 32500 0.0188 0.850 0.0160

40-44 16,20000 11000 0.0068 0.832 0.0057

Total 0.1747

NRR=sum (S.F.R. x S) x 5

= 0.1747 x 5

= 0.8735

PRACTICE QUESTIONS

1. To evaluate the performance of a new diagnostic test, the developer checks it out on 100 known cases of the disease for which the test was designed, and on 200 controls known to be free of the disease. Ninety of

24

the cases yield positive tests, as do 30 of the controls. Based on these data, the specificity and false positive error rates of the test are, respectively,a. 75% and 10%b. 85% and 10%c. 85% and 15%d. 85% and 25%e. 90% and 15%

Based on all the information currently available, you estimate that the patient in your office has a one in four chance of having a serious disease. You order a diagnostic test with sensitivity of 95% and specificity of 90%.

2. The result comes back positive. Based on all the information now available, the chance your patient really has the disease is closest toa. 100%b. 95%c. 90%d. 75%e. 60%f. roughly 30%

3. The result comes back negative. Based on all the information now available, the negative predictive value is closest toa. 1%b. 2%c. 5%d. 10%e. 15%f. 25%

4. Test A has 70% sensitivity and 90% specificity. Test B has 90% sensitivity and 80% specificity. Assuming that responses to Tests A and B are statistically independent, and assuming pre-test probability of disease of 50%, determine the sensitivity and specificity, as well as the positive and negative predictive values, ofa. using Test A and Test B in parallel.b. using Test A and Test B in series, Test A first.c. using Test A and Test B in series, Test B first.

5. A test with 99.9% sensitivity and 99% specificity is used to screen a population for a disease with 1% prevalence. The proportion of test positives in the screen who actually have the disease will be roughlya. 10%

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b. 30%c. 50%d. 90%e. 99%f. 99.9%

6. The American Disease X Foundation reports that 6% of the population over 50 years of age has Disease X. You inquire as to the source of their information, and they cite disease population screening data in the literature which reports that 6% of that population was positive when screened. Referring to the literature, you discover that the screening test used had sensitivity of 95% and specificity of 98%. What proportion of the population over 50 years of age do you think really has the disease?

7. Three tests exist that might be used in screening a population for Disease D, which you believe is present in about 1% of the population. Test A has sensitivity of 99% and specificity of 99.9%. Test B has sensitivity of 95% and specificity of 99%. Test C has sensitivity of 99.9% and specificity of 98%. Using the percentage of test positives to estimate the population prevalence of the disease would most help you support the corresponding institutional position, if you werea. CEO of the American Disease D Foundationb. Newt Gingrichc. Director of the UI's Institute for Truth in Medicine

8. In an article in the Archives of Your Specialty, researchers report that screening Test T is enormously effective, and should be used routinely. As evidence, they report that the five-year survival rate of patients whose disease was discovered by screening with Test T is 90%, whereas the five-year survival rate of patients whose disease was discovered by other means is only 60%. However, in an article that same month in the Journal of the College of Your Specialty, another group of researchers report that screening with Test T has no effect. As evidence, they report that a study which randomized subjects to a program of routine screening with Test T or to no special screening regimen found an 80% five-year survival rate in both groups. The issue seems even more confusing because this second group of investigators acknowledges that if their data are reanalysed to compare the survival rate of subjects who actually followed the screening regimen to those who did not, whatever group they were assigned to, the cohort of those who actually were screened had five year survival of 85% whereas the cohort of those who were not had survival of only 75%. Despite this, these investigators maintain the position that no effect of screening has been demonstrated. Write a brief note for the General Practitioner's Quick Office Practice Digest, explaining why these various sets of results might be expected to in the way they do and advising whether or not to screen with Test T.

9. An article in The New York Times last year, in connection with the prostate cancer treatment of Buffalo Bills head football coach Marv Levy and Washington, D.C. mayor Marion Barry, pointed out that annual prostate cancer diagnoses have almost doubled since 1990, and that most experts attribute this to increased detection of existing cancer via the prostatic specific antigen (PSA) test. The Times article suggested that

26

early detection via the PSA test was leading to early and inevitably more successful treatment of prostate cancer, with a cure rate in the 80-90% range for men with early diagnosis. The Times gave no specific data pertaining to the beneficial effect of the increase in early diagnosis produced by use of the PSA.

Among the data that might be used to support claims that use of the PSA is improving the health outcomes of prostate cancer victims area. the sensitivity and specificity of the PSA test;b. the positive and negative predictive values of the PSA test in the specific population of interest;c. the overall five-year post-dx survival rate (sometimes called the "cure rate" in cancer studies);d. the difference in such rates between men diagnosed by PSA tests as compared to those diagnosed by other means;e. the difference in such rates between men who've previously had one or more PSA tests as compared to those who've not, whatever the method of diagnosis;f. the mean overall post-dx survival;g. the difference in these means between men who've been diagnosed by PSA tests as compared to those diagnosed by other methods;h. the difference in these means between men who've previously had one or more PSA tests as compared to those who've not;i. the age-adjusted mortality rate for prostate cancer;j. the difference in rates of diagnosis between men randomly assigned to receive periodic PSA screening and men randomly assigned to periodic digital rectal examination;k. the difference in five year post-dx survival rates between men randomly assigned to receive periodic PSA screening and men randomly assigned to periodic digital rectal examination;l. the difference in age-adjusted mortality rates for prostate cancer between men randomly assigned to receive periodic PSA screening and men randomly assigned to periodic digital rectal examination.

With reference as appropriate to particular biases, explain why each of the above types of data does or does not provide reliable information on the impact of PSA on the health of men with prostatic cancer.

10. Which of the following is not conducive to success of a medical screening program?a. high incidenceb. long duration of in apparent diseasec. excellent therapeutic results at all stagesd. screening inexpensivee. high specificity of the test

11.To avoid being misled by stage-migration bias in comparing outcomes over different periods of time between which diagnostic acuity has changed, we shoulda. compare stage-specific outcome measuresb. compare directly stage-adjusted outcome measuresc. evaluate outcomes in the later period using the SMR based on reference outcome rates from the earlier periodd. compare outcome measures combining and unadjusted for disease stage

27

ANSWERS

1.c

2.d

3.f

4. a. Sensitivity = 1 - (1-.7)x(1-.9) = 97%; Specificity = .9x.8 = 72%; For PV+, post-test odds = 1x(.97/.28) = 3.46,PV+ = 3.46/4.46 = 1x(.97/.28) = 78%;For PV-, post-test odds = 1x(.03/.72) = .042,PV- = 1 - (.042/1.042) = 96%.

b. and c. Sensitivity = .7x.9 = 63%;Specificity = 1 - (1-.9)x(1-.8) = 98%;predictive values 97% and 73%, calculated as above.

5.c

6. 4.3%

7. a)c

b)a

c)a

8. In the first study there was lead time bias, length/time bias, and compliance bias. In the second study, when they origionally did the randomized clinical trial those biases were gone due to randomization, but when they (non-randomly) re-grouped within the randomized groups the biases came back. The screening therefore does not seem to help.

9. l

10.c

11.d

Source:https://www.med.illinois.edu/m2/epidemiology/ReviewQuestions/SensitivitySpecificity_Questions.htm

EXERCISE

28

https://www.med.illinois.edu/m2/epidemiology/ReviewQuestions/SensitivitySpecificity_Answers.htm

After a New Years Day breakfast of the 22 members (of whom 12 are women) of the Town Council at Restaurant X, a number of the attendees became ill with fever, nausea, vomiting, headaches, abdominal cramps, and diarrhea. Some developed jaundice, and complained of dark colored urine. After interviews with 15 council members, the following line listing was created.

Foods Eaten

ID AGE SEX ILL ILLNESSONSET

Eggs &Bacon

PanCakes Coffee Milk Cup

Cakes

1 38 M Y 1/23 N N N Y Y

2 35 M Y 1/24 Y Y N Y ?

4 35 F Y 1/26 N Y Y Y Y

7 68 F Y 2/2 Y Y Y Y N

8 58 M Y 2/2 Y Y Y N Y

9 53 M Y 2/4 N Y Y N Y

11 57 M Y 2/6 N Y N Y Y

12 59 F Y 2/7 N Y Y N Y

14 33 F N Y Y Y Y N

3 41 M N N Y N N N

5 43 F N Y N ? Y Y

6 61 M N N Y Y Y ?

10 38 F N N Y Y Y N

13 62 F N Y Y Y N ?

15 29 M N ? Y Y Y N

1. In making the decision of whether this is an epidemic/outbreak the key factor is duration of time between exposure and illness

frequency of illness relative to the endemic level

number of people involved

severity of illness

whether the illness was infectious

2. The best estimate of the attack rate per hundred for women is 14 (3/22*100)

32 (7/22*100)

25 (3/12*100)

29

38 (3/8*100)

67 (8/12*100)

3. What is the most likely infected food? eggs & bacon pan cakes coffee milk cup cakes

Two food items are often eaten together (for example, bread and butter) and one item is contaminated with an agent that causes illness and the other is not.

4. After the determination of attack rates for individuals who consumed and did not consume each item:

the contaminated item will show a high relative risk but the uncontaminated one will not.

the uncontaminated item will show a high relative risk but the contaminated one will not.

both items will show high relative risks.

neither item will show a high relative risk.

5. The uncontaminated item is called: an effect modifier

a confounder

a causal factor

a negative correlate

Attack rates were determined for the following four groups of individuals:Group A - consumed item 1 and item 2Group B - consumed item 1 but not item 2Group C - consumed item 2 but not item 1Group D - consumed neither item 1 nor item 2

6. If item 2 is the contaminated item, attack rates will be highest in Groups: A and B

30

B and C

C and D

A and D

A and C

7. The attack rate, as determined from a sudden outbreak of disease, is: an incidence rate

a prevalence rate

an attributable risk

a relative risk

8. An age-adjusted mortality rate for a given population will be lower than the crude mortality rate when that population has

a good health care system.

more efficient methods for handling death certificates.

more elderly people than the standard population.

less elderly people than the standard population.

9. The case fatality rate for a disease could be high for all of the following reasons except no efficacious treatment for the disease has been discovered.

methods for preventing the disease have not been developed.

detection of the disease is difficult during the stage when it is treatable.

the disease moves rapidly to a highly lethal stage.

10. The cause-specific mortality rate for a disease will be high when the prevalence rate and the case fatality rate are both high

the prevalence rate is high but the case fatality rate is low

the prevalence rate is low but the case fatality rate is high

the prevalence rate and the case fatality rate are both low

11. Public health initiatives are concerned with disease prevention and treatment.A public health program which is effective in reducing the probability of acquiring a certain disease for all members of the population should

decrease both the incidence rate and the prevalence rate of the disease.

decrease the incidence rate but increase the prevalence rate of the disease.

not change the incidence rate but decrease the prevalence rate of the disease.

31

not change the incidence rate but increase the prevalence rate of the disease.

not change either the incidence rate or the prevalence rate of the disease.

12. A public health program which effectively provides treatment that prolongs the lives of those in the population with a certain disease should

decrease both the incidence rate and the prevalence rate of the disease.

decrease the incidence rate but increase the prevalence rate of the disease.

not change the incidence rate but decrease the prevalence rate of the disease.

not change the incidence rate but increase the prevalence rate of the disease.

not change either the incidence rate or the prevalence rate of the disease.

The incidence of a certain disease is 6 per 100,000 per year for factory workers exposed to lead dust and 2 per 100,000 per year for similar workers not exposed to lead dust.

13. The relative risk of this disease for those with lead dust exposure is 0.33

2

3

4

6

14. According to the attributable risk, the number of cases of the disease which could be prevented per year for every 100, 000 workers with lead dust exposure is

0.33

2

3

4

6

15. In the investigation of a sudden outbreak of food born disease, potential sources can be identified by the discovery of items with:

high relative risks

high attributable risks

either of the above

neither of the above

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EXERCISE 2

Elderly men with hip fractures were followed to determine the time needed after surgery for them to recover their pre-fracture walking ability. The recovery times had a mode of 9 months, a median of 11.5 months, and a mean of 15.2 months.

1. The frequency distribution of recovery times had at least three peaks.

was symmetric about its mode.

could be well described by the normal curve.

was skewed.

2. The 25th percentile of the recovery time distribution was 9 months.

11.5 months.

less than 11.5 months.

more than 11.5 months.

3. The standard deviation for the recovery time was 8.3 months. The interval given by the mean plus or minus two standard deviations cannot be used to establish normal limits for recovery time because

the normal curve is not a good model for this distribution.

the standard deviation is too large.

the standard deviation is too small.

the standard error is needed instead of the standard deviation.

Sixty percent of patients with pulmonary dysfunction are smokers and 80% of individuals with normal pulmonary function are non-smokers. The prevalence of pulmonary dysfunction in the population is 30%.

4. What is the probability of pulmonary dysfunction for smokers? 0.12

0.32

0.56

33

0.60

0.80

5. What is the proportion of the total population who are non-smokers with pulmonary disfunction?

0.12

0.32

0.56

0.60

0.80

6. What is the prevalence of smoking in the population? 0.12

0.32

0.56

0.60

0.80

The performance measures of a screening test can always be interpreted as probabilities.

7. The predictive value of a positive test is the probability of testing positive given that the disease is present.

the probability of testing negative given that the disease is absent.

the probability of the disease being present given that the test is positive.


8. The sensitivity of the test is the probability of testing positive given that the disease is present.



the probability of the disease being absent given that the test is negative.

9. The predictive value of a negative test is the probability of testing positive given that the disease is present.


34



10. The specificity of the test is the probability of testing positive given that the disease is present.




Four screening test are being considered for early detection of Disease X. The sensitivity and specificity of each test is shown below:

Test Sensitivity SpecificityBlood Test 80% 70%

Physical exam 60% 90%

Ultrasound 90% 60%

Urinalysis 70% 90%

11. Of these four tests, which will fail to detect the most cases of disease X in a screened population?

Blood test

Physical exam

Ultrasound

Urinalysis

One thousand people (500 who have colon cancer and 500 who do not have colon cancer) receive a fecal occult blood test (FOBT). The results are shown in the table below:

Test Colon cancer No colon cancerFOBT positive 300 100

FOBT negative 200 400

Total 500 500

12. Based on these data, we can conclude that the specificity of FOBT as a screening test for the detection of colon cancer is closest to

35

20%

40%

60%

80%

The mean cholesterol level for a sample of cases of women with hypertension during pregnancy was found to be 212 mg%. The lower 95% confidence limit on the population mean was determined as 192 mg%.

13. The standard error was 5 mg%

10 mg%

15 mg%

20 mg%

14. The upper 95% confidence limit was 212 mg%

222 mg%

232 mg%

242 mg%

15. If the mean cholesterol for normotensive pregnant women was 200 mg%, it would be safe to conclude that women with prenatal hypertension have cholesterol levels that are

lower than expected.

higher than expected.

exactly as expected.

perhaps higher or lower than expected.

Volunteers who smoked ten or more cigarettes per day were randomly assigned to use either a nicotine or a placebo inhaler. The subjects were blind to the identity of their treatment. Of the 145 subjects assigned to the nicotine group, 22 eventually quit smoking. There were 7 who quit smoking among the 141 subjects assigned to the placebo group.

16. The relative risk for quitting, associated with the use of the nicotine inhaler, is 0.32

36

3.06

3.42

30.6

34.2

17. Based on a test of the null hypothesis that the quit rates are identical in the two groups, P<0.001, the best interpretation is that

the P-value shows that the difference in quit rates is not clinically significant

a statistically significant difference in quit rates was attained.

the difference in quit rates could easily be explained by chance alone.

less than one in a thousand trials of this kind will result in a difference as large as that found.

18. In a subsequent trial, similar subjects were randomized to either a nicotine inhaler or a nicotine patch. A quit rate of 18.1% was attained in the former group and one of 21.6% in the latter, P>0.10. Therefore,

the P-value shows that the difference in quit rates is not clinically significant .

a statistically significant difference in quit rates was attained.

the difference in quit rates could easily be explained by chance alone.

more than one in a ten trials of this kind will result in a difference as large as that found.

The postnatal weight gain (Y) in pounds over a specified period of time was related to varied amounts of a formula supplement (X), in unit doses, taken during the same period for a sample of 70 infants. The following results were obtained:Regression equation: Y = 1.0 + 0.8 XCorrelation coefficient: r = .64, P<0.05

19. All of the following statements are reasonable conclusions except Infants not taking the supplement are expected to gain one pound during the period.

The extra weight gain, attributed to the supplement, is not likely to be the result of random variation in the data.

There is a strong correlation between weight gain and the amount of supplement taken.

An infant taking 0.5 units of the supplement during the time period is expected to gain 1.4 pounds.

An infant taking 0.25 units more of the supplement than another infant during the time period is expected to gain 0.2 punds more

20. If the weight gain was expressed in grams rather than pounds,

37

the slope would increase and the correlation coefficient would remain the same.

the slope would decrease and the correlation coefficient would remain the same.

the slope would remain the same and the correlation coefficient would increase.

the slope would remain the same and the correlation coefficient would decrease.

the slope would remain the same and the correlation coefficient would remain the same.

Plasma serum levels of betacarotene (Y) in mg/dl were related to body mass index (X1) and cigarette smoking (X2) for a sample of 200 volunteers with a multiple regression equation. The independent variable X2 took a value of 1 if the volunteer was a current smoker and 0 otherwise. The following results were reported:Regression equation: Y = 3.1 - 0.10 X1 - 1.0 X2Coefficient of determination: R2 = .30

21. Tests of the null hypothesis of zero slope gave P-values less than .05 for both independent variables. Thus a smoker with a body mass index of 20 as compared to a non-smoker with a body mass index of 30 is expected to have a beta carotene level which is

2 mg/dl lower.

1 mg/dl lower.

the same.

1 mg/dl higher.

2 mg/dl higher.

22. In using the regression analysis given in the previous problem to estimate the effect of cigarette smoking on levels of betacarotene (i.e. mean levels) we must assume

100% of the variance in betacarotene is accounted for by body mass index and smoking.

the effect of smoking is constant over all levels of body mass index.

all individuals in the population will have the same body mass index.

about half of the population will be current cigarette smokers.

all of the above.

23. The reduction in betacarotene attributed to smoking is likely to be the result of a low coefficient of determination.

random variation in the data.

the fact that smokers tend to have high body mass.

the fact that smokers tend to have low body mass.

38

none of the above.

SECTION – B

Surveillance- Methods, use and example

39

SURVEILLANCELearning Objectives At the end of the session, participants will be able to:

List the various VPDs and their standard case definitions. Define surveillance and list its uses. Explain the steps in conducting VPD surveillance and outbreak investigation Surveillance of Vaccine Preventable Diseases

Each individual case of VPD needs to be recorded and reported upwards within a comprehensive VPD surveillance system. The following section provides an overview of the components of VPD surveillance. Definition of Surveillance Surveillance is data collection for action. It is defined as the ongoing and systematic collection, analysis, interpretation, and dissemination of data about cases of a disease and factors influencing disease behavior, which is used as a basis for planning, implementing and evaluating disease prevention and control activities, including immunization. Key elements of a Surveillance system

detection and notification of VPDs investigation and confirmation (epidemiological, clinical, laboratory) of VPDs collection, analysis and interpretation of data feedback and dissemination of results prevention and control responses

40

Uses of Surveillance Disease surveillance enables the following:

Predicting or detecting disease outbreaks for containment (What disease is occurring) Identifying high-risk populations (Who gets the disease) Identifying areas requiring special attention and where system performance is poor (Where the

disease is occurring) Determining the frequency of occurrence of a disease in the community and magnitude of the

problem (When the disease is occurring and how many get the disease) Identifying underlying causes (or risk factors) of the disease (Why the disease is occurring) Guiding response activities, including immunization (How the disease can be prevented, controlled

or eliminated).

Prerequisites for effective Surveillance Standard case definitions (to ensure uniformity in reporting) Recording and reporting system (to ensure regularity in reporting) List of all the reporting units (to ensure completeness in reporting) The quality of surveillance data depends upon correct diagnostic criteria, timeliness and completeness of reports.

STEPS IN CONDUCTING SURVEILLANCEThe five steps in surveillance, carried out at various levels (sub-center upwards), include:

Step1: Collect data Collect data on the cases and deaths due to all VPDs in your area. The three different data collection methods are: Passive/Routine Surveillance: Data is collected and reported monthly by all the reporting units (from the SC upwards) in the UIP format. However, Weekly reporting is required for AFP surveillance. Detailed information regarding individual cases is essential for diseases under eradication or elimination such as poliomyelitis and Neonatal tetanus. Reliable sources of data for routine surveillance include outpatient and inpatient registers, and individual patient records, including:

Cases that have visited a government health facility for treatment Cases seen by health workers during outreach immunization sessions Cases treated at non-government health facilities e.g. private practitioners, NGO-run hospitals etc. Cases that were reported by ASHA/AWW/community or the media and verified by the visit of a

health worker

41

Active Surveillance: implies the collection of data on specific VPDs, through the review of records during regular visits to selected health facilities, reporting sites or the community. This method is used

During outbreaks to determine the extent of the outbreak and keep mortality rates low by initiating early treatment.

When a disease is targeted for eradication or elimination (e.g. polio eradication) every possible case must be found and investigated.

Active Surveillance does not replace passive surveillance, but if conducted regularly and frequently it has the following advantages over passive surveillance, as it:

helps to improve the timeliness and accuracy of case detection and notification enables rapid case investigation, including collection of laboratory specimens helps to link cases epidemiologically. enables timely action to be taken in response to the detected case identifies areas where passive surveillance needs to be strengthened.

Sentinel Surveillance: Data is collected through reports from selected 'sentinel' sites, to understand the disease burden, monitor trends and detect outbreaks. This system is used when high-quality data are needed about a particular disease that cannot be obtained through a passive system e.g. in AFP surveillance. The sentinel site is usually a hospital, health center, laboratory, rehabilitation center or other facility which attends to a relatively large number of cases of the disease.

Reporting units for VPD Surveillance A reporting unit is a health facility/individual in private or public sector, located in rural or urban area. Designated health workers/paramedical staff and medical officer/practitioner working in various health facilities collect information on VPDs in the specified formats and report these in a timely manner to the next higher level.

Follow these rules when reporting the total number of cases and deaths seen during a reporting period (month or week):

Zero reporting: Submit nil reports even if there are no VPD cases seen. Avoid double counting: if a child makes two visits to the health center for the same disease episode

count it as one case only. Count only those cases which have been diagnosed by the health personnel. Count current cases only: Include only those cases that occurred within the time frame specified for

the VPD.

42

Report the occurrence of any unusual clustering of VPD cases or any death immediately by telephone, fax, email, special messenger etc. This verbal report must be followed by a written case based report.

Step 2: Compile data In terms of passive surveillance, you need to know how many VPD cases are occurring and where they are occurring. The essential data you should receive from each reporting unit in the UIP report of all sub-centers/ PHCs is the number of cases and deaths of each of the targeted diseases counted during the reporting period.In terms of active surveillance, additional information should include the:

Vaccination status of each case; Name, age and sex of each case; Date and place of onset of symptoms

Compile the data to describe the VPDs in terms of time, place and person. This can be done by tabulation or drawing of graphs, bar charts or maps. Table 10.1 describes the immunization status of measles cases (among infants older than 9 months of age) regarding a Measles outbreak in five SCs in a PHC.

43

Step 3: Analyze and interpret the data Regularly review the data from routine reports and check if it crosses the threshold level.Threshold levels are determined based on three criteria: 1. Pre-existing National/Internationally developed thresholds: e.g. a single case of measles in a tribal area is considered an outbreak 2. Based on Historical Data: e.g. if data for a particular disease is available, then the monthly mean should be calculated for the previous three years (excluding months in which there was an outbreak). 3. Increasing trends of the disease over a short duration of time (e.g. in weeks). If the number of cases is found to be much below the threshold, you could interpret it as no cause for worry. Alternatively, you could check for under-reporting or review the threshold value.

If the cases are approaching the threshold level or have crossed it, then suspect an outbreak. Analyze the reports for surveillance quality as follows: 1) Completeness of reporting The number of reports received divided by the number of reports expected, expressed as a percentage. If the completeness of reports was only 50%, then the disease incidence would be under-reported by 50%. 2) Timeliness of reporting The number of reports received on time divided by the number of reports expected expressed as a percentage. The definition of 'on time' must be clear to reporting units.

3) Description by time, place and person (when, where and who gets the disease?) When the disease is occurring? Compare the number of cases and deaths with previous weeks/ months/ years to see if there are any seasonal or cyclic trends. Table, bar or line diagrams are tools that enable analysis across time (temporal). These tools will help you to understand any increase or decrease in the incidence of a disease or the number of deaths for a particular reporting unit (as compared to other reporting units). Figure 10.1 shows yearly trend of measles cases and deaths in a tabular and graphic form.

The above data could be interpreted in the following manner. The increasing number of cases from 1999 onwards indicates a potential outbreak, improved reporting or a change in the detection and reporting protocols. The decreasing number of cases from 2002 onwards indicates improved control measures, under-reporting due to incomplete reports or change in the detection and

44

reporting protocols. The plateau in the graph from 2006 onwards indicates either a stable situation or under reporting because of incomplete reports. Where the disease is occurring? Diseases tend to cluster in a particular area. Clustering indicates that a large number of similar cases have occurred in a limited geographical area or have occurred around the index case. This provides an idea of the causative and predisposing factors that may have played a role in the occurrence of the VPD. See Figure 10.2.

A Spot map is a tool that enables analysis across space (spatial). It shows the occurrence of the cases, high-risk areas, areas of poor immunization coverage or areas with vacancies of HWs. A Spot map helps to identify:

Pockets from where cases are consistently reported Pockets from where cases are expected but not reported Disease trends in comparison to similar maps for the previous corresponding period.

Who gets the disease? VPDs also tend to occur more in specific ages and sexes. Tables, bars or pie charts are tools that enable analysis across specific age and sex groups. A high proportion of un-immunized VPD cases are a reflection of low immunization coverage in the community. You could also compare incidence and case fatality rate between different reporting units and between public and private sources. See Figure 10.3.

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Step 4: Take action After analysis and interpretation of data, take action to correct any problems identified to prevent avoidable morbidity and mortality. If you find that there are:

More cases than you expect: Conduct an outbreak investigation and response. Cases occurring in vaccinated children: This could be due to over-reporting, vaccination given at the

wrong age; incorrect technique of administration or dosage and breaks in the cold chain. Possible interventions to deal with these could be improved supervision, capacity building and strengthening the cold chain.

Fewer cases than you expect: This could be due to under-reporting of cases or actual improvement of services. If the latter is true, there is no need for action.

Step 5: Provide Feedback Feedback to the reporting sites refers to:

Commenting on the completeness, timeliness and accuracy of the surveillance reports; Informing about the effectiveness of the vaccination activities in meeting the objectives of disease

reduction; Offering information to help them in solving problems; Congratulating the good performers and encouraging them to do a better job.

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Feedback is essential to keep the staff motivated to achieve high levels of immunization coverage and to collect accurate and complete data on the occurrence of target diseases. It may be urgent for an outbreak or individual cases or specific e.g. the laboratory results of each AFP case. Feedback to the community helps increase community trust and involvement. It must be shared during monthly meetings as well as during visits to the reporting units.

SECTION – C

OUTBREAK INVESTIGATION

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OUTBREAK INVESTIGATION, RESPONSE AND CONTROLAn outbreak is defined as the occurrence of an illness in a community, clearly in excess of the expected numbers. Usually an outbreak is limited to a small focal area. When an outbreak covers a larger geographic area and has more than one focal point, it is termed as an epidemic. Outbreaks are defined differently for different VPDs. For diphtheria, polio, neonatal tetanus or JE, even a single case is an outbreak, whereas for measles and pertussis, a sudden increase in the number of cases is an outbreak. Refer to GoI guidelines for surveillance and outbreak response for AFP and Measles.SOURCE: Field Guide: Measles Surveillance and Outbreak Investigation, New Delhi, Government of India, 2006, (http://www.npsuindia.org/download/Measles%20Guide.pdf) Field Guide: Surveillance of Acute Flaccid Paralysis, New Delhi, Government of India, 2005, (http://www.npspindia.org/download/Redbook.pdf)

Warning signs of an impending outbreak are: ƒ Clustering of cases or deaths in time and/or space ƒ Occurrence of two or more epidemiologically linked cases of meningitis or measles ƒ Shifting in the age distribution of cases

Investigation of an outbreak helps to: ƒ control and limit its spread to other areas ƒ ascertain its etiology and understand why it occurred ƒ identify high risk areas and groups ƒ assess how prevention strategies can be strengthened to reduce or eliminate the risk of future

outbreaks

Steps in Outbreak investigation Prompt and timely action during an outbreak is critical to minimizing the damage and maintaining public trust in health and immunization services. The emphasis should be on saving lives. Without awaiting confirmation of a suspected outbreak, provide immediate logistic support to the field teams. Once the cause of outbreak is confirmed, does not waste laboratory support for diagnosing

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http://www.npspindia.org/download/Redbook.pdf

every case since, standard case management for epidemiologically linked cases DOES NOT require laboratory confirmation.

Actions BEFORE an outbreak:Form an Epidemic Response Team (ERT) which may include representatives from:

ƒ Local health officials (DIO/ any district level epidemiologist/ district officer in charge of surveillance and the concerned BMO)

ƒ Hospital Clinician/ Public Health Nurse ƒ Laboratory representative ƒ NGO representative/ Community leader ƒ Others as appropriate

The team that has been formed at district level should hold a meeting as soon as a suspected outbreak is identified. It should decide on the area to be surveyed, plan and guide the outbreak investigation, monitor progress in data collection, compile and analyze data and write a final report.

Actions DURING an outbreak

STEP 1: CONFIRM THE OUTBREAK Confirmation of an outbreak is done through two related steps. Firstly, you have to visit the area concerned and confirm the diagnosis of as many reported cases as possible. Next, you should ascertain its geographical spread through a preliminary search. Confirm the diagnosis by: Clinical criteria: according to the standard case definition using information obtained by history and examination Epidemiological association: If an outbreak has been confirmed and similar cases in the same area in the same period of time are reported by health workers, but not investigated individually, they may be confirmed by epidemiologically linked association with confirmed cases. Laboratory tests: For VPDs subject to eradication or elimination, collect laboratory specimens from every suspect case (e.g. stool sample from each AFP case). For VPDs subject to control, collect specimens from a sufficient number of cases (e.g. five blood samples in case of a measles outbreak) to confirm the outbreak. However, no laboratory specimens are required for neonatal tetanus. Ascertain the geographical extent of the outbreak to the surrounding villages/ blocks. The search for additional cases must include visits to: The health facilities: Talk to the doctors and nurses to see if they are seeing suspected cases of the VPD. Visit hospital wards and outpatient departments and search all patient registers for cases that fit the standard case definition. The community: Visit the area from where cases have been seen in the health facilities. Talk to volunteers and other influential persons in the community. If feasible, organize a rapid house-to-house search of the affected area(s) tosearch for similar cases. Identify key informants in each village / ward for prompt information about any cases.

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STEP 2: CONDUCT HOUSE-TO-HOUSE SEARCHES TO FIND ADDITIONAL CASES AND PROVIDE CASE MANAGEMENT Train and assign health workers to conduct house-to-house searches to find the cases in the designated area. The logic is to list all the cases of VPD that have occurred in the recent past. Investigate cases using one disease-specific 'Standard Case Investigation Form' (CIF) for each case. Record the full details, including identification data, address, vaccination status and the travel history. (See Appendix 10.2) Provide standard case management/treatment to the cases. Trace contacts to establish chains of transmission for containment measures such as Outbreak Response Immunization (ORI) in Measles, Polio, etc. If a new case or outbreak has been detected, search for additional cases of the VPD. For example, for a suspect measles or diphtheria case, enquire whether there are any other contacts (in the specific age group) in the household or neighborhood. Provide need-based prophylaxis and/or immunization to the contacts (e.g. vitamin A for measles, vaccination for diphtheria). Health workers should notify the cases with complications to the supervisor for further referral. During the course of investigation, it may be possible that some other areas (not included in initial planning) may report fresh cases of the VPD. Arrange to undertake case searches in these new areas as well. TRACE ELEMENT: A contact is a person who has been in close association with a known or suspected case of a communicable disease during the incubation period.

STEP 3: LINE LIST AND NOTIFY THE CASES From the Case Investigation Forms, create a line list of all cases including the name, address, age, sex and immunization status. Include laboratory results as soon as these become available. Record these in the suggested line list as shown in Table 10.2.

Report the cases immediately to the ERT in both the CIF and the line list consolidating data acquired from all the CIFs.

EXERCISE: Plan a visit to a community and the nearest health centre and see different form available there. See the line listing register.What is the difference between line listing and case finding? See the forms given in appendix used in IDSP.

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STEP 4: DESCRIBE THE OUTBREAK Describe the outbreak in terms of time, place and person. Time: What are the dates of onset of cases? Plot these to prepare an Epidemic curve i.e. a graph showing cases by date of onset or by date of report (See Figure 10.4). It helps to demonstrate where and how an outbreak began, how quickly the disease is spreading, the stage of the outbreak (start, middle or ending phase), and whether control efforts are having an impact.

Place: Where do cases reside? Prepare a Spot map (See Figure 10.2) of the area showing the location of all confirmed cases. It helps to identify areas with clusters of disease. Further investigation of these areas may reveal weaknesses in the local immunization program. Person: Who are affected? The Graph or table of age distribution and immunization status of cases (See Figure 10.3) are prepared from the line list of cases. This information helps to identify the most affected age-groups and those cases which were not preventable (e.g. those developing measles before the scheduled age of immunization).

STEP 5: ANALYZE THE DATA TO: Confirm the outbreak:

Is the number of cases reported greater than the number expected for this period? (e.g. threshold)

What proportion of cases fulfill the case definition? Define the extent of the outbreak (time, place and person) Measure the severity of the outbreak. What proportion of confirmed cases were

hospitalized, suffered complications or died (Case Fatality Rate)

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Measure the effectiveness of vaccination How many confirmed cases occurred in vaccinated individuals and in unvaccinated

individuals? How effective was the vaccine at preventing infection (Vaccine Efficacy)

EXERCISE: Plan a visit to the district health office and medical record section. Interview the DHO and MRD in charge regarding the criteria of confirming the epidemic?

STEP 6: USE THE DATA FOR ACTION Use data on the various components of the immunization system such as coverage, status of the cold chain, training and availability of personnel to determine the causes of the outbreak. The reasons why susceptible accumulate in a group could be the following. Failure to give vaccine: A high proportion of unvaccinated among the cases in an outbreak would suggest that failure to vaccinate children was a significant factor. Spot maps will help to locate cases, high-risk areas and clusters of cases indicating a failure of the program to reach a specific geographic area or population subgroup. Vaccine failure: The vaccines currently in use are relatively safe and effective. However, these vaccines are not 100% effective. For example, the efficacy of measles vaccine is estimated to be approximately 85% when given at 9 months. Cold chain failure: If the efficacy of the vaccine appears to have been low across all age groups, especially during a specific period of time, review the cold chain to ensure that it has been functioning correctly. Identify and rectify the factors contributing to a cold chain failure. STEP 7: WRITE THE REPORT After conducting the outbreak investigation, prepare a short comprehensive report with the following sections:

ƒ Introduction and background information about the area affected (population structure, health facilities, regularity of RI sessions, health seeking behavior)

ƒ Review of status of VPDs and routine immunization (coverage data)

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Case-Fatality Rate (CFR) is based on the case investigations and the total number of confirmed cases. If possible, estimate it by age-group. CFR = No. of patients who died of a specific VPD/Total No. of cases of the same VPD X 100Vaccine efficacy (VE) is the ability of the vaccine to prevent disease effectively and is affected by the age at immunization, potency of the vaccine (quality of cold chain) and overall immunization coverage. VE = (Attack Rate among unvaccinated (ARU) -Attack Rate among Vaccinated (ARV)(Attack Rate among unvaccinated (ARU)Attack Rate is an incidence rate (usually expressed as a percent), used only when the population is exposed to a VPD for a limited period of time, such as during an outbreak. It is calculated as follows: AR= Number of new cases of a VPD during a specified time interval X 100 Total population at risk during the same interval

ƒ Short review of the VPD outbreaks in the past ƒ VPD reporting and surveillance system ƒ Confirmation of outbreak by serology (lab reports) ƒ Data collection methodology (sample size, number of investigating teams, approach etc.) ƒ Data analysis

ƒ Time, place and person analysis of cases (charts, graphs, spot maps etc.) ƒ Age distribution and vaccination status analysis ƒ Analysis of Case Fatality Rate ƒ Probable reasons of outbreak

ƒ Population at risk ƒ Case management ƒ Response to outbreak ƒ Conclusions and recommendations

Send the outbreak investigation report to concerned district and state government officers (See Appendix 10.3).

STEP 8: GIVE FEEDBACK Provide feedback to all levels (Community/ SC/PHC/CHC/District) on the outcomes of the VPD outbreak investigation, in order to ensure that all stakeholders are aware of the reasons for the outbreak, the actions initiated and the plan to prevent future outbreaks.

STEP 9: INITIATE ACTION In all VPD outbreaks, effective case management and follow-up of cases is a priority. Thereafter, conduct activities for strengthening and raising awareness of routine immunization.

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CASE: Follow-up should be according to specific guidelines e.g. re-visit AFP cases after 60 days of Reporting

Suggestions for Classroom Use

At a minimum, before beginning a case study, students will need to know the basic scientific steps for investigating an outbreak. We recommend that teachers prepare for presenting an exercise by reading the case study section by section and attempting to answer the questions before reviewing the answer key. Here are some classroom approaches that have worked well:

To Present a case study

Divide the class into small work groups of five to ten students. Ask each group to assign a facilitator, a recorder, and a reporter.

Hand out Part I and call on individual students from the class at large to read the narrative and questions out loud.

Then have students work in their small groups to answer the questions. Finally, have the groups report their responses to the whole class. Move through the remaining sections in the same fashion.

Note that to avoid giving away answers, you should give students the parts of a case study sequentially, as indicated. The slides related to the case study could be shown during the work session or used in a wrap-up session.

To Evaluate What Students Have Learned

Use traditional testing on specific knowledge points regarding epidemiology and outbreak investigation Use the sample problems and the national event problems found in medical quizzes, international and

national day celebration of public health importance.

To enrich your class' study

Invite local experts to speak to the class. These could include a public health official from the local health department, a physician specializing in infectious diseases, or an infection control nurse from a local hospital.

Introduce students to the NICD, CDC's weekly publication featuring breaking news in national and international health.

Have students access the articles found in Careers in Epidemiology and read, report on, and discuss them. Have students read The Hot Zone, The Cobra Event, or other health-related literature. Show the movie Outbreak. Have students research the pioneers of public health, such as John Snow, John Graunt, and William Farr.

ANNEXURE- 1

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http://www.cdc.gov/excite/careers/index.htm

http://www.cdc.gov/excite/olympiad.htm

EXERCISEMeerut district was reported to be affected by an “outbreak” of acute gastroenteritis (GE) in July-August, 2000. About 2270 cases and 413 deaths occurred during this period. Most of the cases had only diarrhoea and vomiting.

Q.NO.1. How will you decide whether or not the district was in the grip of an outbreak?

(Table-1 Describes the reported data on GE from the Meerut district during 1997-2000)

Table 1

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FORMAT FOR OUTBREAK INVESTIGATION REPORT

General InformationState:_____________________________________________________District: _____________________________________________________Town/PHC:_________________________________________________Ward/Village:_______________________________________________Population:_________________________________________________

Background Information

Person reporting the outbreak: ______________________________

Date of report: ____________________________________________

Date investigations started: __________________________________

Person(s) investigating the outbreak: ______________________________

Details of Investigation

Describe how the cases were found may include: (a) house-to-house search in the affected area; (b) visiting block areas adjacent to the affected households; (c) conducting record reviews of local hospitals; (d) requesting health workers to report similar cases in their areas, etc.):

________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Descriptive Epidemiology

11. Cases by time, place and person (attach summary tables and relevant graphs and maps).12. Age-specific attack rates and mortality rates 13. High-risk age-groups and geographical areas.

Description of Control Measures taken

________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Description of Measures for Follow-up Visits:

________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Brief Description of Problems encountered

________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Factors which, in your opinion, contributed to the outbreak

________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Conclusions and Recommendations

______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Date (Name and Designation)

Note: This report should be submitted by the investigating officer (State/District/PHC Nodal Officer) to the next higher authority within a week of completion of investigation. Tables and Graphs should be included wherever appropriate.

Cases and Deaths due to GE in district Meerut 1997-2000

Year No. of cases No. of deaths

1997

1998

1999

2000

981

375

1387

2380

225

112

173

426

Q.No.1. Now, will you consider it an outbreak of GE? If yes why? If not, why?

________________________________________________________

________________________________________________________

* Analysis of the age distribution of 308 deaths revealed that about 9% of deaths occurred in children below five years of age and about 62% of deaths occurred in adults above 20 years of age.

Q.No.2. Does it help you in suspecting cholera as the cause of this outbreak?

________________________________________________________

________________________________________________________

Q.No.3. What was the most disturbing features in this outbreak? Was it preventable?

* Rectal swabs from 59 cases were examined in the laboratories of NICD, Delhi. 15 Samples were positive for V.cholerae O1 biotype E1 Tor. The isolates were sensitive to tetracycline, nalidixic acid, ampicillin and chloramphenicol, but resistant to furazolidone and streptomycin. The other samples were found negative for any enteropathogens.

Q.No.4. What are the possible reasons for 44 of 59 samples being found negative for entero-pathogens?

________________________________________________________

________________________________________________________

Q.No.5. Assume yourself as the team leader for the investigation of this outbreak. (i) How will you plan the investigations? (ii) How will you control the outbreak?

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________________________________________________________

________________________________________________________

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Student Exercises- Outbreak Investigation

Exercise 1

During the previous year, nine residents of a community died from the same type of cancer. List some reasons that might justify an investigation.

Exercise 2

During August, a county health department received reports of 12 new cases of tuberculosis and 12 new cases of aseptic meningitis. Tuberculosis does not have a striking seasonal distribution; however, aseptic meningitis, which is caused primarily by a viral infection, is highly seasonal, and peaks from August–October. What additional information is needed to determine whether either of these groups of cases is an outbreak?

Exercise 3

Review the six case report forms in the Appendix and create a line listing based on the information.

Case Report Forms

State Disease Report Form


NameMcDowell, D.

Age33

Phone555-3707

Address2020 Alabama

SexM

RaceW

City, StateColumbia

CountyColumbia

Disease Trichinosis

Date of Onset7/27

Lab Confirmation

Muscle Biopsy

Hospital Alerted?

Yes

Hospital NameColumbia General

Admission Date7/27

Discharge Date

Lab Test Results Eosinophilia = 2500

Comments (Clinical description,

immunization theory, etc.)

Possible Exposure

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Cleveland-McKay

Wedding

Physician ReportingDr. Baker

Phone555-1900

Date of Report8/17


NameGordon, Jack

Age26

Phone555-1213

Address110 Clifton St.

SexM

RaceW

City, StateColumbia

CountyColumbia

DiseaseProbable Trichinosis

Date of Onset8/14

Lab Confirmation

Not Done

Hospital Alerted?

NoHospital Name Admission Date Discharge

Date

Lab Test ResultsEosinophilia = 37%



Possible Exposure

Cleveland-McKay

Wedding

Physician ReportingDr. Gibbs

Phone555-3841

Date of Report8/14


NameThomas, Nancy

Age27

Phone555-3761

63

Address2020 Alabama

SexF

RaceW

City, StateColumbia

CountyColumbia

Disease Trichinosis

Date of Onset8/4

Lab ConfirmationNot Done

Hospital Alerted?No

Hospital Name Admission Date Discharge Date

Lab Test ResultsEosinophilia = 18%

Comments (Clinical description, immunization theory, etc.)

Possible Exposure Cleveland-McKay Wedding

Physician ReportingDr. Stanley

Phone555-0400

Date of Report8/14


NameDickens, R.

Age43

Phone555-2662

Address34 Whinfred Ave.

SexM

RaceW

City, StateSeattle, WA

CountyKing

Disease Trichinosis

Date of Onset7/25

Lab Confirmation

Serologic

Hospital Alerted?

NoHospital Name Admission Date Discharge

Date

Lab Test ResultsEosinophilia = 4100



Possible Exposure

Cleveland-

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McKay Wedding

Physician ReportingDr. Webster

Phone555-0511

Date of Report8/15


NameMcKay, Alice

Age54

Phone555-6256

Address406 Tugalo Ln.

SexF

RaceW

City, StateBrighton

CountyClayton

DiseaseR/O Trichinosis

Date of Onset8/14

Lab Confirmation

Not Done

Hospital Alerted?

Yes

Hospital NameColumbia General

Admission Date8/14

Discharge Date

Lab Test ResultsEosinophilia = 3600



Possible Exposure

Cleveland-McKay

Wedding

Physician ReportingDr. Mason

Phone555-3291

Date of Report8/15

Exercise 4

You are called to help investigate a cluster of 17 men who developed leukemia in a community. Some of them worked as electrical repair men, and others were ham radio operators. Which study design would you choose to investigate a possible association between exposure to electromagnetic fields and leukemia?

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Exercise 5

The manager of a grocery store has reported a rash illness among the store’s workers. What type of study would you use to determine the source of the outbreak? Why? What is the appropriate measure of association? After reviewing the table in the Appendix showing the data on exposure to celery for these workers, calculate the measure of association and interpret your results.

Rash No Rash Total

Exposed to Celery?Yes 25 31 56

No 5 65 70

Total 30 96 126

Hints for question no 1

One reason to investigate is simply to determine how many cases you would expect in the community. In a large community, for instance, nine cases of a common cancer (e.g., lung, breast, or colon cancer) would not be unusual. In a very small community, nine cases of even a common cancer may seem unusual. If the particular cancer is rare, then nine cases even in a large community may be unusual.

If the number of cases turns out to be high for that community, we might pursue the investigation further. Our motive might be research—perhaps we will identify a new risk factor (workers exposed to a particular chemical) or predisposition (people with a particular genetic marker) for the cancer. Control and prevention may also be a justification. If we find a risk factor, control and prevention measures could be developed. Alternatively, if the cancer is generally treatable when found early and a screening test is available, then we might try to determine not why these people developed the disease, but why they died from it. For instance, if the problem were cancer of the cervix, detectable by Pap smear and generally treatable if caught early, we might find (1) problems with access to health care, or (2) physicians not following the recommendations to screen women at the appropriate intervals, or (3) laboratory error in reading or reporting the test results. We could then develop measures to correct the problems we found (public screening clinics, education of physicians, or laboratory quality assurance).

If new staff needs to gain experience on a cluster investigation, training may be a reason to investigate. If there is public concern, it may generate political pressure. Perhaps one of the people affected is a member of the mayor's family. A health department must respond to such concerns, but does not usually need to conduct a full-blown investigation. Finally, legal concerns may prompt an investigation, especially if a particular site in the community is implicated.

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Hints for exercise 2

You need to know how many cases of each of these diseases usually occurs in this county during August. Because tuberculosis is not seasonal, the number of cases could be compared with (a) the numbers reported during the preceding several months and (b) the numbers reported during August of the preceding few years. However, since aseptic meningitis is seasonal and peaks from August–October, the number of cases during August is expected to be higher than the number reported during the preceding several months, so you would need to compare with the numbers reported during August of the preceding few years.

Hints for Exercise 3

The choice of information to include in a line listing is somewhat arbitrary. The following categories are often included:

Identifying information Identification number or case number, usually in the left-most column Names or initials as a cross-check

Clinical information Physician diagnosis Was diagnosis confirmed? If so, how? Symptoms Laboratory results Was the patient hospitalized? Did the patient die?

Descriptive epidemiology—time Date of onset Time of onset

Descriptive epidemiology—person Age Sex Occupation, if relevant, or other seemingly relevant characteristics

Descriptive epidemiology—place Street, city, or county Worksite, school, day care center, etc., if relevant

Risk factors and possible causes Specific to disease and outbreak setting

Here is one way that a line listing might be drawn up from the six case report forms on the Cleveland-McKay wedding outbreak:

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ID # Initials Date of Onset Diagnosis How

Confirmed Age Sex County PhysicianCleveland-

McKay Wedding

1 KR 7/23 probable trichinosis Not done 29 M Columbia Goodman Yes

2 DM 7/27 trichinosis Biopsy 33 M Columbia Baker Yes

3 JG 8/14 probable trichinosis Not done 26 M Columbia Gibbs Yes

4 RD 7/25 trichinosis Serologia 45 M King Webster Yes

5 NT 8/4 trichinosis Not done 27 F Columbia Stanley Yes

6 AM 8/11 R/O trichinosis Pending 54 F Clayton Mason Yes


Because the total population at risk is not well defined, you would use a case-control study. You would begin by enrolling the 17 people already identified with leukemia as the case group. You would also need to determine what group might serve as an appropriate comparison, or control, group. Neighbors might be used for the control group, for example. In your case-control study, you would determine whether each case-patient and each control had been exposed to electromagnetic fields (however you defined that exposure). Finally, you would compare the exposures of case-patients and controls.


You would use a cohort study because the outbreak is small and confined. The appropriate measure of association for a cohort study is relative risk, which is calculated in this case as the attack rate for workers exposed to celery divided by the attack rate for those who were not exposed.

The attack rate for exposed workers is 25 / 56, or 44.6%. The attack rate for workers who were not exposed is 5 / 70, or 7.1%. Thus, the relative risk for exposure to celery is 44.6 / 7.1, or 6.3. This means that workers who were exposed to celery were 6.3 times more likely to develop the rash illness than those who were not exposed, and it is therefore likely that celery was the source of the outbreak. However, before you could draw this conclusion, you would need to compare the relative risk for celery with that for other vegetables and fruits to see if the implication is stronger for any of them.

Then, to test the likelihood of your findings, you would need to calculate a test of statistical significance such as chi-square for the item with the highest relative risk and look up the corresponding p-value in a table of p-values. If the p-value was below .05, your findings would be considered statistically significant.

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Source: 1. cdc.gov. Excite, learning epidemiology2. Immunization guide for immunization for medical officer

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SECTION – D

Exercises on Research Methods [for Promotion of Lung Health]

Practical exercise

Cause or association?

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Scenario

A descriptive study in a large population of teenagers and young adults (n=25 000) has shown a statistically significant association between the use of a new bronchodilator drug and the risk of dying from asthma. On the basis of this finding there is a public outcry demanding the withdrawal of the drug from the market.

Would you regard this as justified?

If no, what explanation would you give?

If yes, on what grounds?

What further information would you need in order to evaluate whether or not this new drug causes fatal asthma?

Practical exercise

Choosing Research Questions for Protocol Development

An essential aspect of the learning experience in this course is for small groups to work together throughout the week on the development of a written research protocol. Based on past experience, the identification and precise

71

formulation of the study questions to be addressed by the protocol groups is the first major potential stumbling block in the course. The following exercise may be helpful to assist course instructors and participants in coming to decisions about study questions in a timely fashion, so that sufficient time is left for groups to work on the details of the protocols.

The exercise can be done individually, or as a group ‘brainstorming’ session. The first step is best completed on the first day of the course, and steps 2 and 3 on the second day (after the participants have had a chance to discuss topics informally among themselves and with faculty).

1. Choosing the general domains or topic areas for focus

Relevance to health in the community:

Among conditions affecting lung health, the most frequent serious conditions in your region are (list them, be specific):

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

What criteria did you use to select these conditions?

Is the list the same for other countries (or regions)?

Interests and experience of the research team; Relevance to the political and social imperatives

Are there specific research questions or topics of particular interest to you or your colleagues, or that you know are of particular interest to managers of health services or health spending in your region (list them):

1.

2.

3.

4.

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5.

6.

7.

8.

9.

10.

2. Narrowing the focus

Combining aspects from the two lists above, list (? in order of priority), several topics or research questions for protocol development.

Questions for the group to consider: What criteria will you use to decide what topics remain on the list? to decide the order of priority? (interest of participants - ? by vote, consensus; fundability; seriousness of the disease; frequency of the disease; prior experience of participants)

In previous courses, participants have found it useful to select 4 to 6 general topic areas that address different diseases (or health-related states), or that reflect differing types of study populations (eg. clinical topics, health service delivery issues, community or workplace studies, evaluation of treatments).

1.

2.

3.

4.

5.

6.

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3. From general ‘topics’ to study questions and specific objectives

At some point in the study question development process, participants in previous courses have found it useful to fill in templates similar to the ones below for the study topics / questions identified (either after the initial brainstorming – to help narrow the focus, or after 4-6 topics have been chosen).

Studies of disease in populations (natural history, determinants, etc)

Disease or health-related state

Target population

Determinant(s) of interest

Feasible? Significance?

Intervention possible?

Most likely study design

Epidemiologic studies of clinical procedures, treatments, interventions, diagnostic tests

Procedure, intervention, etc

Patient group Outcome to be assessed?

Feasible? Significance?

Implementation likely?

Experimental design possible?

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Practical exerciseStudy Design

The following are a group of selected abstracts of scientific articles on lung health published in recent years (slightly edited for purposes of this exercise). Each abstract describes a scientific study of an epidemiological nature, giving setting, objectives, design, results and conclusions.

Read each abstract and then define what type of study design is described in the abstract, using the enclosed standard form and taking into account the elements described in the preceding section.

In assessing the study design, first ask the question:Was only one group (either a group of patients, or a group with a common experience/exposure) studied?

If the answer is no, ask:Did the investigator choose which group an individual would be in or assign interventions to groups?

If the answer is no, ask:When selecting the groups to be studied, did the investigator begin by selecting groups defined by the presence or absence of disease, or did the investigator select according to the presence or absence of a common factor or exposure?

If the answer is no, ask:Was the presence of disease and of the factor or exposure thought to be associated with the disease measured at the same point in time?

The answers to these questions should allow you to correctly determine which type of study design the investigators have selected.

ABSTRACTS:

Study 1 - Short course chemotherapy for tuberculoma of the brain

Setting: Tuberculosis Research Centre, Madras, IndiaObjective: The efficacy of a short-course regimen in the treatment of brain tuberculoma and computerized tomography scan appearance before, during and after antituberculosis treatment was studied.Design: Patients aged over 5 years with tuberculoma of the brain diagnosed by CT scan were randomly allocated to one of the following 2 regimens:

Regimen 1: rifampicin, isoniazid and pyrazinamide daily for an initial 3 months followed by rifampicin and isoniazid twice-weekly for 6 months;

Regimen 2: rifampicin, isoniazid and pyrazinamide thrice-weekly for an initial 3 months followed by rifampicin and isoniazid twice-weekly for 6 months.

The patients were followed intensively for 2 years from the start of treatmentResults: Of the 108 patients analysed (regimen 1: 56, regimen 2: 52), at the end of treatment clinical status was normal in 91% in regimen 1 and 88% in regimen 2. Of the 91 patients with scan assessments, CT scan lesions disappeared at 24 months in 77% of 47 patients in regimen 1 and 80% of 44 in regimen 2, and in both groups 88% of the patients were clinically normal. None had relapses requiring treatment.Conclusions: Short-course regimens of 9 months’ duration are effective in the treatment of tuberculoma of the brain; clinical recovery was faster than scan clearance.

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Study 2 - Cigarette smoking as a risk factor for tuberculosis

Setting: The association between smoking and pulmonary tuberculosis has not often been studied.Objective: To assess the influence of cigarette smoking on the development of active pulmonary tuberculosis in young people who were close contacts of new cases of smear-positive pulmonary tuberculosis.Design: A comparison of 46 patients with active pulmonary tuberculosis and 46 patients with positive tuberculin tests but no active tuberculosis. Smoking habits were investigated using a questionnaire. Analysis was performed and odds ratios adjusted for age, gender, and socio-economic status.Results: Statistically significant differences were found in active smokers (OR 3.7, 95%CI 1.5 to 9.2). There was a dose-response relationship between the number of cigarettes smoked daily and the risk of active pulmonary tuberculosis.Conclusions: The data studies show that cigarette smoking is a risk factor for pulmonary tuberculosis in young people.Tuber Lung Dis 1996;77:112-116

Study 3 - Impact on adherence of change from injectable to oral regimen

Setting: Out-patient tuberculosis clinics in Dar es Salaam, TanzaniaObjective: To measure the impact on patient adherence to directly observed ambulatory tuberculosis treatment of substituting an all-oral regimen for one containing streptomycin.Methods: The attendance of patients during the intensive phase of treatment was measured daily at two outpatient clinics. During the observation period, treatment was changed from one containing stretptomycin to an all-oral regimen and attendance proportions were compared when patients always, sometimes or never received streptomycin during their treatment.Results: No significant difference was observed in attendance between periods when patients received streptomycin and when they were given an all-oral regimen.Conclusions: Patient adherence to a completely oral regimen was indistinguishable from that when streptomycin was used. Clear advantages in reduced cost, time and danger of nosocomial HIV infection are obvious with the all-oral regimen.Tuber Lung Dis 1995;76:286-289

Study 4- Resistance to antituberculosis drugs in Cameroon

Setting: Tuberculosis centre in Hopital Jamot, Yaounde, the sole referral facility for tuberculosis treatmentObjectives: To identify strains of M tuberculosis responsible for pulmonary tuberculosis and to determine the prevalence of initial resistance to the main drugs used for treatment and to compare this prevalence between those HIV positive and HIV negativeDesign: 576 consecutive, previously untreated, adult patients with smear positive pulmonary tuberculosis, admitted between July 1994 and December 1995 were studied. Standard species identification was carried out. Sputum was cultured on Lowenstein-Jensen and Coletsos media. Susceptibility of isolates to major drugs was tested using the indirect proportion method. HIV testing was performed with 2 ELISAs and confirmed with Western Blot.Results: M. tuberculosis was isolated in 516 (90%) of the cases. Of the 516 cases, 92 (18%) were HIV positive. Of the 516 strains isolated, 164 (32%) were resistant to at least one drug. Resistance was noted as follows: 25% to one drug, 5.8% to 2 drugs, and 1% to three or more. Initial resistance was most frequent to Streptomycin (20.5%), followed by isoniazid (12.4%), rifampicin (0.8%) and ethambutol (0.4%). No significant difference was observed between HIV-positive and HIV-negative patients.Conclusion: Initial drug resistance to M tuberculosis is relatively high in Yaounde.Int J Tuberc Lung Dis 1997;1:110-114

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Study 5 - Yield of acid-fast smears in laboratories in Tanzania

Setting: Routine laboratories in Tanzania performing sputum smears for acid-fast bacilliObjectives: To determine the yield of smear examination under routine conditions in a low income country where tuberculosis is common.Design: Analysis of routine records in 34 rural smear laboratories using a common, standardized recording system, identified 61,580 tuberculosis suspects with 141, 371 sputum smear examinations. Incremental yield of subsequent sputum smears was determined based on the results obtained in those reported.Results: The average proportion of cases found among suspects was 19% (range 14-24%). The incremental yield of subsequent sputum smear examinations was estimated to be 83%, 12% and 4% on the three smears examined.Conclusions: The incremental yield of a third examination, after two have been examined is relatively low. The proportion of suspects found to be positive was higher than previously noted.Trans Roy Soc Trop Med Hygiene 1996;90:258-261

Study 6 - Efficacy of BCG in Malawi

Setting: A district in Northern Malawi where BCG was introduced in 1974 using the Glaxo, freeze-dried vaccineObjectives: To determine the protective efficacy of this vaccine against tuberculosis and leprosyDesign: The presence of a BCG scar was prospectively determined in 83,455 individuals residing in the district and followed from 1979 to 1989 to determine whether they developed tuberculosis or leprosy. Results: 414 new cases of leprosy and 180 new cases of tuberculosis were identified. Protection against leprosy was estimated at 50% or greater in those with BCG scars, whereas no statistically significant protection could be demonstrated against tuberculosis.Conclusions: BCG affords better protection against leprosy than against tuberculosisLancet 1992;339:636-639

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Evaluation of Study Designs

Study 1 Study 2 Study 3 Study 4 Study 5 Study 6

Is this study design experimental?

Is it a cross sectional study?

Is this a prospective cohort study?

Is this a retrospective cohort study?

Is this a case-control study?

Explain why you selected this study design:

Study 1

Study 2

Study 3

Study 4

Study 5

Study 6

78

Practical exerciseCase-control and Cohort Studies

A causal relationship between cigarette smoking and lung cancer was first suspected by clinicians in the 1920s on the basis of clinical observations. To test this apparent association Richard Doll and Austin Bradford Hill carried out two major studies. . The first was a case-control study, begun in 1947, in which the smoking habits of lung cancer patients were compared with the smoking habits of other patients. The second was a cohort study, begun in 1951, which related causes of death among doctors to their previously recorded smoking habits.

Part I: Case-control study

Data were obtained from patients in hospitals in and near London, over a 4-year period. Initially, 20 hospitals, and later more, were asked to notify the investigators of all patients admitted with a diagnosis of lung cancer. These patients and controls selected from in-patients with other disorders (primarily non-malignant) in the same hospitals at the same time were then interviewed about their smoking habits.A total of 1,465 cases of lung cancer, all under age 75, were included in the study. These patients were culled from a larger number of which about 15% were not interviewed because of death, discharge, severity of illness, or inability to speak English.Diagnoses of lung cancer in nearly all cases were based on biopsy, autopsy, sputum cytology wih or without bronchoscopic or radiographic evidence.Interviews were conducted by four full-time social workers. Each worker, after interviewing a patient with lung cancer, interviewed a control patient of the same gender and the same 5-year age group. Table 1 compares cases and controls in terms of age and gender.

Table 1. Age and gender of cases and controls

Cases ControlsAge group Men Women Men Women

25-34 17 3 17 335-44 116 15 116 1545-54 493 38 493 3855-65 545 34 545 3465-84 186 18 186 18Total 1,357 108 1,357 108

Table 2. Number and per cent of male cases and controls by amount smoked

Number of daily cigarettes

Cases Controls

Number % Number %

0 7 0,5 61 4,51-4 49 3,6 91 6,7

5-14 516 38,0 615 45,315-24 445 32,8 408 30,125-49 299 22,0 162 11,950+ 41 3,0 20 1,5

Total 1,357 99,9 1,357 100,0All smokers 1,350 99,4 1,296 95,5

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The study showed a clear association between smoking and lung cancer(Table 2), but differences between case and control patients, particularly in terms of questionnaire response, might make the association spurious. Did lung cancer patients, knowing they had lung cancer, tend to exaggerate their smoking habits? Did controls, knowing smoking is ‘bad for you’ tend to under-report their smoking? Did interviewers, through prior knowledge of the hypothesis tend to exaggerate the smoking habits of lung cancer patients and minimize the smoking of controls? Possible answers to these questions came from patients initially interviewed as presumed lung cancer cases but later found not to have the disease. Table 3 compares the smoking habits of men aged 45-74 in this and other diagnostic groups.

Table 3. Percentage distribution of daily smoking habits for selected disease groups (standardized to age distribution of population of England and Wales)

Average daily number of cigarettesDisease group 0 1-4 5-14 15-24 25+ Number of patientsIncorrectly presumed to have cancer 5,3 9,9 35,5 37,8 11,4 202Confirmed lung cancer 0,3 4,6 35,9 35,0 24,3 1,224Other lung diseases 1,9 9,9 38,3 38,7 11,2 301Other cancers 4,6 9,4 47,2 26,0 12,8 473Other diseases 5,6 9,0 44,8 26,9 13,7 875

Questions re Case-control Study

1. How representative of all persons with lung cancer are cases admitted to hospital likely to be?

2. How representative of all persons without lung cancer are other patients in hospital likely to be?

3. What biases may have been introduced by failure to interview 15% of the cases?

4. Why did the investigators require that control patients be of the same gender and age group as case patients?

5. What do the data of table 2 suggest about the relationship between cigarette smoking and lung cancer?

6. Compute the odds ratio for lung cancer occurring in all smokers compared with non-smokers. What does this represent? What does it suggest with regard to the etiological role of cigarette smoking in lung cancer?

7. If the ‘control’ patients were asthma patients, would this change your opinion about the etiological role of cigarette smoking in lung cancer based on the results of this study?

8. What does table 3 tell us? Why was age standardization of the data required?

Part II. Cohort study

In 1951, a prospective cohort study was undertaken to quantify the relation between smoking and lung cancer. The study population comprised all physicians listed in the Medical Register and resident in England and Wales in October 1951. Information about present and past smoking habits was obtained by questionnaire. Deaths from lung cancer were identified from death certificates and other mortality data recorded during ensuing years.

In October 1951 questionnaires were mailed to 59,600 physicians, seeking self-classification under any of 3 smoking groups: [1] current smokers, [2] ex-smokers and [3] non-smokers. Smokers and ex-smokers were asked the amount they smoked, their method of smoking, the age they started to smoke, and, if they had stopped smoking, how long it

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had been since they last smoked. Usable responses to the questionnaires were received from 34,445 (85%) of the male physicians.

The occurrence of lung cancer in physicians who responded to the questionnaire was documented over the next 10 years (November 1951 to October 1961) from death certificates filed with the Registrar General and from lists of physician deaths provided by the British Medical Association. All certificates indicating that the deceased was a physician were abstracted. For each lung cancer case, medical records were obtained to confirm the diagnosis. The same clinical and pathologic criteria were used as in the earlier case-control study. Of 4,597 deaths in the cohort over the 10 year period, 216 were reported to have had lung cancer, a diagnosis that could be documented in 4, leaving a net total of 212 cases of lung cancer.

Table 4 shows lung cancer deaths by age and amount smoked. Rates are both age-specific and age standardized (ëall agesí category) and are expressed as deaths per 1,000 person-years at risk.

Table 4. Age-specific lung cancer death rates per 1 000 person-years at risk, by age group and amount smoked

Average number of cigarettes smoked daily0 1-14 15-24 25+

Age group Number Rate Number rate Number rate Number rate35-44 1 0,05 1 0,07 0 - 1 0,1145-54 0 - 3 0,31 9 0,62 8 0,7555-64 0 - 3 0,48 20 2,31 26 3,8865-74 0 - 9 2,69 17 5,16 14 6,4875+ 2 1,11 6 2,68 8 7,27 8 16,33

Total all ages(Standardized) 3 0,07 22 0,57 54 1,39 57 2,27

The relation between lung cancer mortality and cessation of smoking is shown in Table 5.

Table 5. Lung cancer deaths, rates in smokers, ex-smokers and non-smokers

Smoking habit Number of lung cancer deaths Rates per 1 000 person-years

Current smoker 124 1,28Ex-smoker for:

<5 years 5 0,675-9 years 7 0,49

10-19 years 3 0,1820+ years 2 0.19

Non-smoker 3 0,07

Questions re Cohort study

1. What proportion of male physicians answered the questionnaire? How might this affect comparability of smokers and non-smokers in the study?

2. From table 4, compute and interpret values of relative and attributable risk for the “total” group.

3. What do the data in table 5 imply for health education services?

81

Practical exerciseClinical trials

The following are various scenarios illustrating clinical trials. Read the scenarios and answer the questions.

Scenario 1

A new anti-tuberculosis medication has been developed which has shown good in vitro activity and low toxicity in phase 2 (safety) trials. A randomised control clinical trial is now being planned.

Which of the following groups would you consider to be the most appropriate controls and why? What are the disadvantages of the groups you do not select?

No Yes1. Patients who receive the current standard 2-drug therapy in your clinic

If no: disadvantages2. Patients who receive a placebo drug

If no: disadvantages3. Patients who receive only one of the two drugs in current use

If no: disadvantages4. Two groups, one on the current two drugs and one on placebo

If no: disadvantages

Scenario 2In a trial of Haemophilus influenzae type b conjugate vaccine involving 60 000 infants, children born on odd dates during a twelve month period received the vaccine in a four dose schedule plus the routine infant immunisation schedule vaccines. Those born on even dates served as controls and received only the routine vaccine schedule.

What factors would have entered into the calculation of numbers of infants in the trial?

Was the method of allocation to vaccine and control groups satisfactory?

What alternative method might have been adopted?

How would you go about identifying cases of invasive Haemophilus disease?

What sources of bias might enter into case ascertainment?

82

Practical exerciseAdvantages and Disadvantages of Different Study Designs

Complete this table by placing one or more “+” or “ –“ marks or short comments in the boxes to provide a quick comparison of the advantages and disadvantages of these different study designs.

Experi-mental study

Prospective cohort study

Retro-spective cohort study

Case-control study

Cross-sectional study

Descriptive (non-analytic) study

Can measure disease incidence

Can evaluate more than one outcome from the same risk factorCan evaluate several different risk factors for the same diseaseFollows the natural time sequence of exposure and diseaseUseful for rare exposures or risk factors

Useful for rare diseases

Useful for diseases with long latency periods

Logistics? (eg. keeping track of study groups? Quality control in method?)Number of subjects needed

Cost

Results available quickly

Uses existing data

83

Practical ExerciseSampling a population

We propose to do a study of knowledge of tuberculosis in a group who are members of a scientific society. We have obtained a list of the members (see next page) from the register of members of the association and we will obtain a sample of the members to administer a questionnaire.

List the frequencies of the variables gender, language, region, TB and BACT. Select the first 8 members in the list. List the frequencies of the same variables in the table. Select every 5th member in the list. List the frequencies of the same variables in the table.

Variable All members First 8 Every 5th

GenderMen

WomenDon’t know

LanguageFrenchEnglish

SpanishDon’t know

TBYesNo

Don’t knowBact

YesNo

Don’t know

1. Are the three groups the same?

2. Which of the samples is closest to the whole group?

3. Why?

4. What conclusion would you draw about the geographic focus of the society from the first eight cases?

5. Why is this conclusion misleading?

6. What will be the effect of those cases where the value is not known?

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List of members of a scientific society

NUMBER GENDER LANGUAGE REGION TB BACT

1 MAN SPANISH AML NO NO2 MAN ENGLISH AMN YES NO3 MAN ENGLISH MIE NO NO4 MAN ENGLISH MIE NO NO5 MAN ENGLISH NO NO6 FRENCH AFR YES YES7 MAN ENGLISH ASI YES YES8 MAN ENGLISH ASI NO YES9 ENGLISH AFR NO NO

10 MAN ENGLISH AFR NO NO11 MAN ENGLISH AMN NO NO12 MAN FRENCH AFR YES YES13 MAN ENGLISH AFR NO NO14 ENGLISH MIE NO NO15 MAN ENGLISH NO NO16 MAN ENGLISH AFR NO NO17 WOMAN SPANISH AFR YES NO18 WOMAN SPANISH AML NO NO19 MAN ENGLISH MIE YES YES20 MAN SPANISH AML NO21 SPANISH AML NO NO22 MAN AFR YES NO23 MAN AMN YES YES24 WOMAN ENGLISH AMN YES NO25 MAN ENGLISH AFR NO NO26 MAN ENGLISH AFR NO27 MAN ENGLISH AFR NO NO28 ENGLISH AMN YES NO29 MAN ENGLISH ASI NO NO30 ENGLISH ASI YES YES31 FRENCH AFR NO NO32 MAN ENGLISH AMN YES NO33 WOMAN FRENCH AFR NO NO34 MAN ENGLISH AFR NO NO35 WOMAN ENGLISH EUR NO NO36 MAN ENGLISH AMN YES YES37 MAN ENGLISH EUR NO NO38 MAN ENGLISH AFR NO NO39 MAN ENGLISH ASI NO NO40 MAN ENGLISH AFR YES NO41 MAN FRENCH AFR NO NO42 MAN FRENCH EUR YES YES

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Practical exercise

Random error and sample size

When a coin is flipped, the result, ie. heads or tails, is a random event (provided it is a fair coin, and the person flipping it is not a trickster).

Question: If you were to conduct an experiment to test if a coin is fair, what proportion of the time would you expect the coin to land with ‘heads up’? (ie. what is the hypothesized result of the experiment?)

Exercise: Let each person in the group conduct his or her own experiment to test a coin. Each person flips a coin 5 times and records the number of times the coin lands heads up, then compute the percentage ‘heads’. If there are 25 people in the group, this exercise is similar to doing the same study (with n=5 ‘tosses’), 25 separate times.

Put the results in the following table:

Percent ‘heads’ Indicate with a mark for each person 0%20%40%60%80%100%

Repeat this series of experiments, this time with each person flipping their coin 25 times. Again each persons calculates the percentage ‘heads’ from his or her own ‘study’.

Percent ‘heads’ Indicate with a mark for each person 0-10%11-20%21-30%31-40%41-50%51-60%61-70%71-80%81-90%91-100%

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Record the results from the two series of experiments as frequency histograms on the following graphs.

Results from first series of ‘studies’ with n=5

Results from second series of ‘studies’ with n=25

Questions:

1. What can you conclude about the most likely percentage of ‘heads’ one would obtain from a single study? Does this ‘most likely’ value change when the sample size of the study is larger or smaller?

2. What can you conclude about the expected ‘variation’ in results due to chance when the sample size is smaller v. larger.

3. If a colleague were to tell you that she tested a coins by flipping it several times and she found it came up ‘heads’ 20% of the time, could she conclude that the coin is rigged?

4. Two colleagues came to you with results of their studies on 2 different coins. They each tested different coins by flipping them several times and they found one came up ‘heads’ 20% of the time (ie. a ‘head rate’ of 20%) and the other came up ‘heads’ 65% of the time (a ‘head rate’ of 65%).

What is the difference in ‘head rates’ between the two studies? What is the rate ratio?

Are you confident that these differences are real? What additional information would you need to know in order to decide in the coins are similar?

87

Practical exercise

Using sample size / power calculations in protocol development

Case studies and some recent epidemiologic studies have suggested a possible link between some occupational and environmental exposures and idiopathic pulmonary fibrosis (IPF).

1. To address the question, “Is there an association between ‘idiopathic’ pulmonary fibrosis (IPF) and occupational exposure to solvents or metals?” describe several possible study designs that could be considered.

2. One of your colleagues is the medical director for a large metal trades employer and you have access to health records for all employees in the company for the past 35 years. Therefore, you have decided on a retrospective cohort study. All employees with 1 or more years of employment since January 1, 1965 will be enrolled in the cohort. They will be divided into exposure subgroups according to job records and company exposure information. You will compare rates of IPF among the exposure sub-groups.

What additional information do you need in order to calculate the whether or not the available workforce is large enough to do this kind of study?

3. Using Epi-Info, calculate the sample size needed for a cohort study given the following assumptions and decisions:

Null hypothesis: There is no difference in IPF rates between workers exposed to solvents and metals combined compared to workers not exposed to either.

alpha=0.05 ; power = 0.80

Effect size, based on: expected ‘baseline’ IPF rate = 6 / 1,000,000 person yearsexpected risk ratio = 2 (ie. risk of IPF expected to be double in the exposed group)

Sample size required: _______________

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4. Do the same calculation several more times, varying one or more of: alpha, power, and ‘expected risk ratio’, to complete this table:

Sample size / power estimates for a cohort study of occupational exposure to solvents and metals and IPFassuming a baseline IPF rate (among non-exposed) of 6/1,000,000 persons per year.

Risk ratio = 2 Risk ratio=2.5 Risk ratio=3 Risk ratio=4Power = 80% Alpha=0.01 Alpha=0.05Power=90% Alpha=0.01 Alpha=0.05

5. If the baseline rate of IPF is actually lower than 6 / 1,000,000 per year, would you expect the required sample size to be lower or higher? Check your answer by doing another Epi-Info calculation.

6. After investigating the company records, it is evident that there are only 1000 employees who have been exposed to solvents and metals. Therefore, based on the sample size calculations, the research team decides that a cohort study is not feasible and decides to explore the case-control design instead. All pulmonologists and pathologists in the region are polled and they agree to submit all their IPF cases over the 2 years to the study. Based on estimates of the number of IPF cases seen in the previous 2 years, you anticipate about 200 cases for the study.

Using Epi-Info, calculate what odds ratio a study of this size should be able to detect (with alpha=0.05 and power of 80%). What additional information about the expected study population is needed to do this calculation?

7. Compare the minimum detectable odds ratios for this kind of study, for expected baseline exposure prevalences of 2%, 20%, 50%, and 90%. What do you conclude about study power in relation to the prevalence of exposure in the population?

89

Practical exerciseMeasurement - Defining variables

Characteristics of the variables to be used in a study are key in determining what instruments will be used, the size of the population to be studied and how the results will be analyzed.

Specifying the type of variable

The following are outcome variables frequently used in studies of lung health. Please indicate the type of each variable:

Variable Type

TuberculosisFEV1 levelTuberculin reactionPneumoniaAsthma severitySmear positive TBLung cancerEmphysemaARI

The following are a number of factors or determinants often studied for their association with lung diseases. Indicate the type of each variable:

Variable Type

PovertyBacterial exposureTobacco smokingDust exposureGenderAgeEthnic groupHeightImmune competence

Which of the variables listed above could be expressed in different forms (eg. as either categorical or continuous?)

Give an example of a categorical measure of ‘poverty’ and a continuous measure of ‘poverty’.

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Definition of variables

Consider the following list of definitions of tuberculosis used in articles published in the International Journal of Tuberculosis and Lung Disease, from the first quarter of 1999

1. Reported patients with sputum smears positive for acid-fast bacilli in Botswana

2. A patient with a definitive diagnosis of pulmonary (positive culture and / or clinical and radiological diagnosis) and / or extra-pulmonary tuberculosis (positive culture) in London

3. Tuberculosis diagnosed on the basis of clinical, radiological, or microbiological results in Italy

4. Tuberculosis confirmed by acid-fast bacilli positivity on smear or culture, and / or granulomatous inflammation with caseous necrosis in the pulmonary biopsy specimen in Turkey

5. Isolates of Mycobacterium tuberculosis in the Netherlands

6. Every newly-diagnosed tuberculosis patient in New Caledonia confirmed on culture in the Institut Pasteur

7. All patients commencing treatment for tuberculosis in two districts of Uganda

Is it possible to conclude something about “tuberculosis” by simply summarizing the conclusions of all these studies?

Is it the same disease being referred to in each of these studies?

What “elements” are common to each of these definitions?

If you were going to list results or attributes from each of the studies that are comparable across all studies, how would you do it?

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Practical exercise

Defining disease

The following are a group of children who have come to a health centre in the rural area of a low income country:

A 4 year old child brought by his mother who has tuberculosis. The child has a cough and weight loss, a positive tuberculin skin test and has a shadow on the chest radiograph.

A 2 year old child who has been ill for 5 months with failure to thrive and fever. A 6-month old child with fever and a positive skin test. An 8-month old child who lives with his uncle who has tuberculosis. A 3 year old child who has fever and weight loss for 6 weeks and has a shadow on the chest radiograph. A 2 year old child who, on enrolling in a child care centre, has a shadow on the chest radiograph.

1. Which of these children has tuberculosis?

2. Do the others definitely not have tuberculosis?

3. How do you know? (What are the criteria you use to decide?)

4. Which criteria have the greatest weight in considering the diagnosis?

5. Which have the least?

6. Why?

7. If this was a sample from a larger group of children being studied, what difference would varying the criteria for diagnosis make on the results of the study?

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Practical exerciseMeasuring disease

The purpose of this practical is to introduce you to the use and limitations of mortality statistics and disease rates. You should understand how these statistics are obtained and know the most common causes of death at different ages. You should aim to be conversant with the following terms introduced here.

Medical certificate of cause of death; Parts I and II of the certificate; Death certificate; Underlying cause of death; International Classification of Disease (ICD) Code; The difference between numbers and rates; Crude mortality rate; Age and cause specific mortality rates; Age standardization and Standardized Mortality Ratios (SMRs); Incidence rates and prevalence rates.

Please complete the following questions:

1. Study the case history which follows and the specimen medical certificate of cause of death. Complete it and place the International Classification of Disease Code beside the one underlying cause of death.

Death certificateInternational Statistical Classification of Diseases and Related Health Problems, (ICD-10)

World Health Organization 1991

Cause of deathApproximate

interval between onset and death

IDisease or condition directly leading to death*

(a)…………………………………………. ………………..

Due to (or as a consequence of)

Antecedent causesMorbid conditions, if any,Giving rise to the above cause,stating the underlying condition last

(b)…………………………………………. ………………..


(c)…………………………………………. ………………..


(d)…………………………………………. ………………..

IIOther significant conditions contributing to the death, but not related to the disease or condition causing it

…………………………………………….. ………………..

…………………………………………….. ……………….

This does not mean the mode of dying, e.g. heart failure, respiratory failure. It means the disease, injury, or complication that caused death.

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Case history

History: Four years before his final hospital admission, this 64-year old man had an admission to hospital for acute shortness of breath. Lung function showed reduced FEV 1 with response to bronchodilator. He was treated with inhaled beta agonists and beclomethasone. One year later, he was again admitted to hospital and required a period of artificial ventilation for respiratory failure. Subsequently, he regular ambulatory oxygen at home. He returned to hospital on this occasion because of breathlessness. He started smoking cigarettes at age 16, averaged 30 per day and stopped smoking after his last admission.

Examination: CVS – pulse 78 / min; regular. RR 50 / min; prolonged expiration with expiratory wheeze; increased anteroposterior diameter to the chest with hyper resonance; cyanosis noted.

Other examination normal.

Investigations: Hb 11,8 g / dl; Urine – no protein or sugar; Spirometry showed reduced FEV 1 (18% of predicted) with reduced FEV / FVC (40%).

Arterial blood gases – paO 1 markedly reduced and paCO 2 elevated.

Clinical course: Admitted to the Intensive Care Unit and intubated; following day developed fever and left shift to WBC; tracheal secretions yielded Pseudomonas aerugenosa resistant to all common antibiotics; developed progressive infiltration on chest radiographs; oxygenation progessively deteriorated; developed acute chest pain, ventricular fibrillation and expired.

Post mortem: not performed.

3. The Incidence rate of a disease is the rate per unit time at which the previously unaffected develop the disease. The prevalence ratio of a disease at any time is the proportion of the population affected.

What will tend to raise or lower the prevalence ratio of a disease apart from its incidence rate?

How might you measure incidence and prevalence, for example, of asthma?

INTERNATIONAL CLASSIFICATION OF DISEASE 10 th REVISION

Ischemic heart disease(I20-I25)

I20 Angina pectoris

I20.0 Unstable anginaI20.1 Angina pectoris with documented spasmI20.8 Other forms of angina pectorisI20.9 Angina pectoris, unspecified

I21 Acute myocardial infarction

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I21.0 Acute transmural myocardial infarction: of anterior wallI21.1 Acute transmural myocardial infarction: of inferior wallI21.2 Acute transmural myocardial infarction of other sitesI21.3 Acute transmural myocardial infarction of unspecified siteI21.4 Acute subendocardial myocardial infarctionI21.9 Acute myocardial infarction, unspecified

I24 Other acute ischemic heart disease

I24.0 Coronary thrombosis not resulting in myocardial infarctionI24.1 Dressler’s syndromeI24.8 Other forms of acute ischemic heart diseaseI24.9 Acute ischemic heart disease, unspecified

I49 Cardiac arrhythmias

I49.0 Atrial arrhythmiaI49.1 Ventricular arrhythmiaI49.9 Cardiac arrhythmia, unspecified

J13 Pneumonia due to Streptococcus pneumoniae

J14 Pneumonia due to Hemophilus influenzae

J15 Bacterial pneumonia, not elsewhere classified

J15.0 Pneumonia due to Klebsiella pneumoniaeJ15.1 Pneumonia due to PseudomonasJ15.2 Pneumonia due to staphylococcusJ15.8 Other bacterial pneumoniaJ15.9 Bacterial pneumonia, unspecified

J41 Simple and mucopurulent chronic bronchitis

J42 Unspecified chronic bronchitis

J43 Emphysema

J43.1 Panlobular emhysemaJ43.2 Centrilobular emphysemaJ43.8 Other emphysemaJ43.9 Emphysema, unspecified

J44 Other chronic obstructive pulmonary disease

J44.0 Chronic obstructive pulmonary disease with acute lower respiratory infectionJ44.1 Chronic obstructive pulmonary disease with acute exacerbation, unspecifiedJ44.8 Other specified chronic obstructive pulmonary diseaseJ44.9 Chronic obstructive pulmonary disease, unspecified

J45 Asthma

J45.0 Predominantly allergic asthma

95

J45.1 Nonallergic asthmaJ45.8 Mixed asthmaJ45.9 Asthma, unspecified

J46 Status asthmaticus

J47 Bronchiectasis

Practical exercise

Measuring disease

An international collaborative study was made of the results of treatment of new cases of pulmonary cases that were smear positive. Of 492 cases in British Columbia, Canada, 5.1% died during the course of their treatment as compared with 3.0% of 3,163 cases in Sudan. The same definitions for outcome of treatment were used, following the recommendations of the IUATLD.

1. Can we conclude that treatment in Canada is worse than in Sudan?

2. What other information would be necessary to compare the deaths in the two countries?

3. How would this information be used to improve the validity of the comparison?

96

Practical exerciseMeasurement: using standardized instruments

The following exercises are meant to illustrate the issues associated with measurement in epidemiological studies. The two exercises presented are simple exercises which illustrate the problems frequently encountered with measurements and their interpretation.

The first exercise is the interpretation of chest radiographs. Four radiographs will be presented and these should be interpreted by the participants according to a standard format, following the directions on the Radiography report form which is appended to this exercise. Anyone can participate, regardless of qualification or previous experience.

The exercise will illustrate variation in interpretation of a commonly used test which is often considered an essential item for diagnosis of chest diseases. The exercise is based on standard reading of chest films which has been developed for the reading of chest radiographs for the presence of pneumoconiosis, developed by the International Labor Office.

The second exercise illustrates the use of a standard Respiratory symptoms questionnaire, in this case, an expanded version of the bronchial symptoms questionnaire developed by the IUATLD for the study of asthma.

97

Radiography Report Form

Film number [ ]To answer the questions, please choose the appropriate box and mark an x in the box; if you are unsure of the answer, please choose ‘no’.

Quality of the film

no yes

1. Adequate exposure? [ ] [ ]

2. Proper position? [ ] [ ]

Parenchymal shadows

no yes

3. Round shadows? [ ] [ ]If yes:

Smaller than 2 millimeters? [ ] [ ]Larger than 2 millimeters? [ ] [ ]

Location:R upper? [ ] [ ]L upper? [ ] [ ]R lower? [ ] [ ]L lower? [ ] [ ]

4. Irregular shadows? [ ] [ ]If yes:

Smaller than 2 millimeters? [ ] [ ]Larger than 2 millimeters? [ ] [ ]

Location:R upper? [ ] [ ]L upper? [ ] [ ]R lower? [ ] [ ]L lower? [ ] [ ]

5. Calcification? [ ] [ ]

6. Cavity? [ ] [ ]

Pleura

7. Presence of thickening? [ ] [ ]

8. Presence of calcification? [ ] [ ]

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ASTHMA QUESTIONNAIRE – Selected questions

Interviewer (initials) Today’s dateday mo Year

STUDY NUMBER SUBJECT ID NUMBER

Date of Birth Gender: Male Femaleday mo year

GENERAL RESPIRATORY HEALTH QUESTIONS

The following questions are about your lung health IN THE PAST 12 MONTHS. Please answer yes or no. If in doubt about the answer, please answer no.

At any time in the past 12 months:

A. Have you had wheezing or whistling in your chest, when you did not have a cold? 1.Yes __ 2. No __

B. Have you woken up with a feeling of tightness in your chest? 1.Yes __ 2. No __

C. Have you been woken by an attack of coughing? 1.Yes __ 2. No __

D. Have you been woken by an attack of shortness of breath? 1.Yes __ 2. No __

E. Have you had an attack of shortness of breath that came on during the day when you were not doing anything strenuous?

1.Yes __ 2. No __

F. Have you had an attack of shortness of breath that came on after you stopped exercising?

1.Yes __ 2. No __

A. Which of the following statements best describes your breathing?

Check one:1. I rarely get trouble with my breathing2. I do get regular trouble with my breathing but it always gets completely better3. My breathing is never quite right

HISTORY OF ASTHMA

1. Have you ever had asthma? 1.Yes __ 2.No __

IF YES TO '1', ask:

A. Do you still have it? 1.Yes __ 2.No __B. Was it confirmed by a doctor? 1.Yes __ 2.No __C. At what age did it start? ___________yearsD. if you no longer have it, at what age did it stop? ___________years

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SUBJECT ID NUMBER

OTHER ILLNESSES

A. Did you have any lung trouble before the age of 16?

1.Yes __ 2.No __

B. Have you ever had pneumonia? 1.Yes __ 2.No __if yes to B ask:

How many times have you had pneumonia? ___________times

Age at first episode: ___________years

Age at last episode: ___________years

The following questions are about some parts of your background which may be important to us in evaluating your health. Please answer to the best of your memory.

TOBACCO SMOKING

SMOKING BY PEOPLE LIVING AROUND YOU:

When you lived at home:A. Did your father smoke? 1.Yes ___ 2.No ___B. Did your mother smoke? 1.Yes ___ 2.No ___

In your current householdC. Do any members of your current household smoke? (other than you)? 1.Yes ___ 2.No ___

YOUR CIGARETTE SMOKING

D. Have you ever smoked cigarettes? (No means less than 20 packs of cigarettes or less than one cigarette a day for one year)

1.Yes ___ 2.No ___

IF YES TO 'D', ask:

1. Do you now smoke cigarettes? (as of 1 month ago) 1.Yes ___ 2. No ___2. How old were you when you first started regular cigarette smoking?

______________years3. If you have sopped smoking cigarettes completely, how old were you

when you stopped? ______________years4. How many cigarettes do you smoke per day now? __________________

cigarettes per day5. On average, for the entire time that you smoked, how many cigarettes

did you smoke per day?__________________cigarettes per day

100

SUBJECT ID NUMBER

FAMILY HISTORY

As some illnesses are associated with childhood and family history we would like to ask you about your family members, and about your childhood.

Check one:1.Yes 2. No 3.Don’t know

Was your natural father ever told by a doctor that he had:1. Emphysema2. Lung cancer3. Asthma

Was your natural mother ever told by a doctor that she had:1. Emphysema2. Lung cancer3. Asthma

What was your country of birth ____________________________

In what country did you spend the majority of the first 10 years of your life? ____________________________

Were these first 10 years spent in the (check one only):

Countryside or small village 1.Town smaller than 10,000 people 2.City 10,000 to 100,000 people 3.City larger than 100,000 people 4.

What was your father's usual occupation? _____________________________

What was your mother’s usual occupation? _____________________________

YOUR CURRENT JOB (or last job, if you are not currently working)

1. Who is your current employer (name of company): _____________________________

2. What type of industry or sector is this: _____________________________

3. What is your job? _____________________________

4. In this job, are you exposed regularly to dust, gases, or fumes? 1. Yes 2. No __

5. In any previous job, were you exposed regularly to dust, gases, or fumes? 1. Yes 2. No

101

Practical ExerciseInterpreting Results: validity and generalizability of results

A study was undertaken to determine whether the results of treatment of smear positive cases of pulmonary tuberculosis had changed over time. It was expected that, with the improvements in modern treatment, the results would have improved. A similar number of cases was selected from the records of a tuberculosis ward for three calendar periods, 1968-1969, 1973-1975 and 1982-1983. The results of treatment were as follows:

Period Total (%) Successful (%) Positive (%) Died (%) Abandoned (%)

1968-1969 89 (100) 61 (69) 8 (9) 5 (6) 15 (17)1973-1975 89 (100) 61 (69) 15 (17) 7 (8) 6 (7)1982-1983 90 (100) 52 (58) 12 (13) 7 (8) 19 (21)

Statistical analysis, using the chi-square test, was performed and the p=0.12, leading the investigators to conclude that there was no change in the response to treatment over the period studied.

1. Is this conclusion valid? (check one) yes [ ] no [ ]

2. If no, what might lead the investigators to draw a wrong conclusion?

Factor Category Studied (%) Not studied (%)

TOTAL 268 (100) 580 (100)

Age group 15-34 66 (25) 148 (26)35-54 95 (35) 201 (35)

55 + 107 (40) 231 (40)

Extent of disease Limited 152 (57) 391 (67)Advanced 116 (43) 189 (33)

Gender Male 190 (71) 410 (71)Female 78 (29) 170 (29)

The patients chosen for study were part of the whole group of smear positive cases who had been diagnosed and recorded in the years under study. They comprised 37% of such cases in 1968-1969, 24% of cases in 1973-1975 and 38% of cases in 1982-1983. The studied cases were not different from the whole group of patients in age (p=0.96), gender (p=0.95) or ethnic origin (p=0.35). There was, however, a significant difference in the extent of pulmonary tuberculosis among those studied compared with the whole population (extensive tuberculosis was present in 43% of those studied and 33% of those not studied, p=0.003).

3. Is the sample a valid reflection of the condition of all the patients in this locality?Check one [ ]yes [ ] no

102

4. Is it justifiable to conclude that the results obtained in the sample apply to the whole group of patients diagnosed and recorded in this community?

Among the group studied, the results of treatment were not different in the two gender groups (p=0.24), nor in the various ethnic groups (p=0.10) but were different in different age groups (p<0.001) and between those with extensive and those with less extensive disease (p=0.001).

5. Which factor(s) would be most likely to contribute to a wrong conclusion concerning the trend in results of treatment?

6. How would you control for confounding in this situation?

7. Will this ensure that the results are valid?

Practical exercise

Interpreting results: Confounding

Please refer to the following text and tables to carry out this exercise.In a study of the epidemiology of tuberculosis in Denmark, Horwitz (Am Rev Respir Dis 1974;104:22-31) showed that tuberculosis was more common in men than in women and that it was much more common in those who were unmarried than in those who had been married. The results of a study determining the relation of marital status to tuberculosis notification in Canada from 1970-1972 is shown in table 1.

Table 1. Active tuberculosis (number of cases and average annual rate per 100 000) by gender and marital status, Canada 1970-1972

Women MenAge group Single

Married / Separated

Widowed / Divorced TOTAL Single

Married / Separated

Widowed / Divorced TOTAL

All No 1 122 3 140 703 4 965 2 113 4 641 640 7 394Rate 19,5 21,4 26,3 21,5 29,7 31,7 80,0 32,8

Grzybowski S. Evaluation of the Tuberculosis Problem and Control Measures in Canada. National Sanatorium Association, 1977

103

In table 2, the same data are displayed, in this case showing the distribution by age in addition to gender and marital status.

Table 2. Active tuberculosis by age, gender and marital status, Canada 1970-1972

Women MenAge group Single

Married / Separated

Widowed / Divorced ALL Single

Married / Separated

Widowed / Divorced ALL

15-24 No 549 281 4 834 638 129 767Rate 13,3 15,5 13,8 14,0 12,6 13,5 12,7

25-34 No 229 732 44 983 372 565 13 950Rate 42,6 20,1 21,3 22,9 42.3 16,4 23,1 21,7

35-44 No 104 720 47 871 300 818 35 1 153Rate 39,3 21,8 29,7 23,4 79,0 24,1 44,1 29,9

45-54 No 74 607 77 758 300 1 038 85 1 423Rate 29,0 20,8 25,5 21,8 99.0 34,7 83,3 41,9

55-64 No 71 432 116 619 247 1 049 110 1 406Rate 28,3 23,2 22,3 23,5 102,2 47,9 84,1 54.9

65+ No 95 368 415 878 256 1 042 397 1 695Rate 30,8 32,5 28.7 30,4 102,9 61,9 96,3 72,3

1. In table 1, is there a difference in notification rate according to marital status? 2.3. Which group has the highest rate (specify one group by the 3 variables)?

_____________(age)__________(gender)__________(marital)4. Why do you think this is so?

5. In table 2, are the conclusions you drew from table 1 valid? Yes [ ] No [ ]6. Which group in the table contributes the largest number of cases?

_____________(age)__________(gender)__________(marital)

7. Which group has the highest risk for tuberculosis?_____________(age)__________(gender)__________(marital)

8. Why is there a difference?

9. How would you modify the results displayed in table 1 to reflect reality?

104

One decade later, we further examined this association in the city of Vancouver. The results are presented in table 3.

10. In table 3, are the conclusions you drew from table 2 valid? Yes [ ] No [ ]

11. What is the cause of the difference in rates between ever married and never married men?

Table 3. Active tuberculosis(per 100 000 per year) in Vancouver 1980-1982 in adult Canadian-born men according to socioeconomic status and marital status.

Ever married Never marriedSocioeconomic level Number Rate Number Rate

TOTAL 43 22 42 37

High 3 3 5

12

Middle 21 22 13 20Low 19 299 24 326

Enarson DA, et al. Am J Epidemiol 1989;129:1268

105

Practical exerciseInterpreting results: Standardization of rates

The following table gives the situation concerning prevalence of significant skin reactions to tuberculin in residents of Honduras and of Canada, along with their populations:

Prevalence of significant tuberculin reactions in Honduras and Canada

Canada Honduras

Agepopulation cases rate

(%)population cases Rate

(%)

TOTAL 27,000,000 8,100,000 30 3,510,000 1,072,275 31

0-14 1,890,000 0 0 1,120,000 43,971 4

15-24 5,130,000 0 0 910,000 115,379 13

25-34 6,210,000 0 0 700,000 295,400 42

35-44 4,320,000 540,000 13 390,000 262,681 67

45-54 3,780,000 1,890,000 50 210,000 183,204 87

55-64 3,510,000 3,510,000 94 110,000 101,640 92

65+ 2,160,000 2,160,000 100 70,000 70,000 100

Calculate the rate of tuberculin skin reactivity in the two populations, standardized for age and enter into the table.

What is the explanation of the difference between the crude rate and the standardized rate?

What are the advantages of the standardized rates over the crude rates?

What are the disadvantages of presenting only the standardized rates?

106

Practical exercise

Role of statistical testing in research

from The Epidemiology of tuberculosis in gold miners with silicosis. Cowie RL. Am J Respir Crit Care Med 1994; 150:1460-1462.

These investigators carried out a 7 year prospective study of 1153 South African gold miners. At the start of the study, 818 of the miners had silicosis and 335 did not. Each miner was tested for active tuberculosis each year for the 7 years of follow-up. The investigators were interested in knowing if miners with silicosis were more likely to develop tuberculosis than those without silicosis.

Results (at the end of 7 years)

Silicosis p-valueNo Yes

number studied 335 818

pulmonary TB (n) 20 128extra-pulmonary TB (n) 3 27total TB (n) 23 155

pulmonary TB (%) 6.0% 15.6%extra-pulmonary TB (%) 0.9% 3.3%total TB (%) 6.9% 18.9%

extra-pulmonary TB / total TB (%)

13.0% 17.4%

total TB (% per year) 1.0% 2.7%

1. What do you conclude from these results with respect to the rates of pulmonary and extra-pulmonary tuberculosis among these two groups of miners?

2. Do you think the groups differ with respect to the proportion of total tuberculosis that is extra-pulmonary?

3. Recalculate the proportions of extra-pulmonary to total TB for the miners without silicosis, if there were 1 fewer case (and 1 more case) of extra-pulmonary TB in that group (ie. 2 or 4 cases instead of 3). Does this change your answer to question 2?

4. In what way would statistical testing help you answer these questions?

107

Practical exercise

Describing results

Microbial inciters of acute asthma in urban Nigerian children

Gbadero DA, Johnson ABR, Aderele WI, Olaleye OD. Thorax 1995; 50:739-745.

Objective: to determine how often acute exacerbations of asthma in children are associated with acute respiratory infection, to identify the associated pathogens, and to proffer appropriate therapeutic suggestions.

Study population: subjects were recruited from asthmatic children attending the Pediatric Asthma Clinic of the University College

Hospital over a 16 month period children were included in the study if they were previously diagnosed as having asthma, and visited the clinic with

an acute exacerbation with duration of symptoms prior to visit of less than 48 hours; only 1 episode was recorded per child

Methods:

clinical features recorded included: antecedent or concomitant symptoms; household / socioeconomic factors; frequency of previous asthma exacerbations; anthropometric measurements

laboratory measures included: chest radiograph; hematology, serology and cultures (venous blood); virological studies (nasopharyngeal aspirate)

What is the name of this study design?

Sample data table

subject id

age (yrs)

sex race date of visit

weight (kg)

height (cm)

virus identified (yes/no), if yes: type

bacteria identified (yes/no), if yes: type

xray inflamm? yes/no

rhinor-rhoea? yes/no

fever? yes/no

sore throat? yes/no

crowding at home? yes/no

.. ..

1234567. .

86

Discuss how to summarize the information collected (don’t focus on statistical analyses, rather think about how to summarize the information). Prepare 1 or 2 tables (without numbers, just headings for the rows and columns) to describe the information collected for the study.

Hints:

108

1. Consider the study objectives. What is the main question being asked?2. Are there two groups (or subgroups) being compared (this may not be explicit).3. What is the health outcome being investigated? What risk factors were measured?4. What is/are the main comparisons needed to answer the study questions?5. How can you display the results in order to show the comparisons clearly?

109

Practical exercise - 2

Describing results

Risk Factors for Rifampin Mono-resistant Tuberculosis

R. Ridzon, C. G. Whitney, M.T. McKenna, J. P. Taylor, S.H. Ashkar, A.T. Nitta, S.M. Harvey, S. Valway, C. Woodley, R. Cooksey, I. M. Onorato; Am J Respir Crit Care Med, 157, 1998, 1881-1884

Objective: to investigate the relationship between rifampin mono-resistant tuberculosis and use of rifabutin and to identify other risk factors for rifampin mono-resistant tuberculosis among patients with and without HIV infection

Study population: multi-centre study (9 US cities) cases (age 20+) selected from cases of tuberculosis reported to CDC's national surveillance database from 1993 to

1995 with a first M. tuberculosis isolate resistant to rifampin and without resistance to isoniazid, ethambutol, or streptomycin.

2 matched controls 20 yr of age or older were chosen per case from tuberculosis cases with isolates demonstrating susceptibility to isoniazid, rifampin, ethambutol, and, if tested, streptomycin. Controls were the two next reported patients who matched the case by city of residence (or county, if from a rural area), HIV status, age within 5 yr and start of tuberculosis treatment within 3 mo.

What is the name of this study design?

Methods: Medical records were reviewed, including tuberculosis clinic records, hospital records, private provider records, and HIV clinic records (when applicable). Information collected included demographics (age, sex, race, birth place), history of homelessness, incarceration, HIV status, prior tuberculosis, diarrhea, and medications taken at the time of and prior to the current diagnosis of tuberculosis.

Sample of selected results (fabricated!)

subject id rifampin resistant

age sex race home less

birth place

HIV status prior tb prior O.I.

prior jail

diar-rhea

rifabutin use

. .

1 yes 33 m b y US p n y . . . .2 no 56 m a y US p n y3 no 46 m w n US n n n4 no 40 f w n US n n n5 yes 68 m h n US n y n6 yes 21 f a y China n n n7 no 63 m h n US n n n8 no 30 m h y US p n n9 no 39 m w y S.Afr. p n y

10 no 35 m a n US n n n. .

190 no 70 f b y US n n n

110

Practical exercise

Critical review of a publication

Please read the paper provided and then think about the answers to the questions.

1. What was the main aim of the study?

2. What type of study was undertaken?

3. Was this appropriate to the objective and could any other design have equally well been used?

4. Were there any important flaws or weaknesses in the study design or its execution?

5. How might these (if any) have affected the results and how might they have been avoided?

6. What was the main statistical finding?

7. Were the data appropriately analyzed and adequately displayed?

8. If not, what further or alternative analysis could you have done?

9. What were the study’s main conclusions?

10. Do you think the conclusions were justified on the evidence presented?

111

ANNEXURES

OUTBREAK INVESTIGATION(Trigger & Response Mechanisms)

InIDSP

112

Level 1 (ANM/ MPW)Serialno

Syndrome Trigger event Action taken

1. Acute watery stools More than 5 cases in 1000 population

1. Treat with appropriate antibiotics.2. Treat with ORS3. Refer to PHC if dehydration is

severe.4. Inform MO PHC5. Collect water samples and send to

PHC for analysis.6. OT testing7. Check TCL stock (bleeching

powder)8. Train the local person about

chlorination of water.9. IEC for Community awareness about

safe water and personal hygiene.2. A ) Fever < 7 days

duration

a) Only fever

b) With rash

c) Alteredconsciousness

5 cases in 1000population.

Even single in the village

Even single case in the Village

1.Slides for MP with presumptive /RT for malaria2. Inform MOPHC.3. IEC for community awareness.

1. Collect slide for MP.2. Refer the case to PHC3. Inform MOPHC4. Give vitamin A5. Give paracetamol.6. Check immunisation7. Surveillance for Aedes EgyptiLarvae in the house.

a. Containersb. Coolers, etc

1. Collect slide for MP.2. Refer the case to CHC/DH3. Antipyretics4. Inform to PHC5. Vector surveillance6. IEC

113

d) Fever withbleeding

e) Fever withconvulsions

B) Fever more than 7 days

Even single case in the Village

Even single case in the village above 5 years of age group

More than 2 cases in 1000 population

1. Refer the case to CHC/DH2. Inform to PHC3. Vector surveillance4. IEC

1. Refer the case to CHC/DH2. Inform to PHC3. Vector surveillance4. IEC

1. Give paracetamol.2. Collect slide for MP.3. Give anti malarial treatment.4. Inform to PHC.5. OT testing of drinking water.6. Collect water sample and send it to PHC for analysis.7. Check TCL stock.8. Train local person about water Chlorination.9. Community awareness about safe water and Personal hygiene.

3. Jaundice More than 2 cases in 1000 population.

1. Refer to PHC2. Inform MOPHC3. Search for antenatal cases withjaundice in 2nd/3rd trimester.4. Collect water samples for analysisand send it to PHC 5. OT testing.

4. Unusual event More than 2 deaths orhospitalization

1. Inform MOPHC2. Community awareness

114

Level 2 Medical Officer Level (PHC/CHC)

Serialno


1. Acute watery stools >5 cases in 1000 population forsome geographical area

Verify the information from ANM. Confirmation of the outbreak. Active search of cases with standard

case definition. Standard case management. Stool sample collection for Cholera. Ensure safe water supply. Inform district authority and ask for

help SOS. IEC. Documentation. Ensure buffer stock.

2. Typhoid More than 2 cases forsome geographical area

Verify the informationfrom ANM

Confirmation of theoutbreak

Active search of cases with standard core definition

Stool sample collection Standard case management Ensure safe water supply Inform district authority and ask for

help SOS IEC Documentation Ensure buffer stock Blood culture for S typhi.

3. Viral hepatitis 2 cases or more ofjaundice from onegeographical area.

Clinical verification. Standard case management. Active search of cases. Ensure Safe Water supply. Stool samples for virus isolation. Serological investigation. Active search for 2nd/3rd trimester

cases with jaundice and keep them under observation with referral to district hospital SOS.

Investigation of water Treatment

115

Plant/pipeline Leakages.4. Measles Even a single

suspected case Verify the case through clinical

manifestation. Send samples for laboratory testing. Standard case management. Active search of cases. Ring vaccination. IEC Vitamin A.

5. JapaneseEncephelitis

Even a singlesuspected case.

Verify the information. Clinical confirmation. Standard case management. Active search of cases with standard

case definition. Vector surveillance and control. IEC Vaccination as a preventive

measure. Subsequently inform to higher

authority. Isolation of virus. Sero-diagnosis Referral of serious cases to district

hospital.7. DF/DHF Even a single case

of suspectedDF/DHF from acommunity of 1000population.

Verify the information. Suspect if clustering of fever cases

with M.P. negative slides are found. Confirmation of outbreak. Standard case management. Active search of cases with standard

case definition. House-to-house vector surveillance

for A.. Egypti Larvae. Fogging/spraying if necessary. Inform the DHO. IEC Empty the coolers, vessels and keep

them dry for 24 hours at least once in a week.

Remove garbage. (containers etc.)8. Malaria Even single case

is found malaria+ ve in an areawhere malaria

Mass survey for fever cases. Microscopic examination within 24

hours Start CRT to all fever cases/all

116

was not presentfor minimumthree months.SPR rise morethan double overlast three months.Single death frommalaria (clinical/microscopically).Single PF case ofindigenous origin.

contacts of +ve cases and all migratory population. (in case of single PF case of indigenous origin isfound)

Focal spraying with synthetic pyrethyroid

Fogging daily X 3 days followed by biweekly for 3 weeks.

Larvicidal application Elimination of mosquitogenic places

by tempting of water tables, land filling, channelizing the drains.

Activate DDC/FTD Involve local bodies and community

by IEC. Daily surveillance for 3 to 4 weeks.

9. Unusualsyndromescausing death orhospital admission

Hospitalization ordeath of minimumtwo cases of similarillness from samegeographical area.

Verification of the rumor. Clinical verification of cases. Basic Life Support and emergency

medical care. Refer to appropriate hospital if

necessary. Active search of cases. Autopsy and preservation of body

fluid and tissues of vital organs for laboratory diagnosis.

IEC to avoid panic. Reporting to the higher authority.

Level 3 District Level/Medical College

117

Serialno


1. Acute watery diarrhea/cholera.

>5 cases in 1000population from same geographical area.

1 District Nodal Officer Verifies the information from Medical Officer PHC/CHC2 Confirmation of the outbreak with the help of data analysis3 Analysis of laboratory sample if any.4 Rapid Response teamVisit to the site

Confirm the outbreak Std. Case management Active search of cases with

standard case definition Stool sample collection Ensure availability of

essential drugs and establishDepot center.

Ensure safe water supply. Inform State authority and ask

for help SOS. IEC. Documentation. Feedback

2. Typhoid More than 2 cases for some geographical area

1 District Nodal Officer Verifies the information from Medical Officer PHC/CHC2 Confirmation of the outbreak by data analysis3 Analysis of laboratory sample if any.4 Rapid Response team Visit to the site.

Confirm the outbreak Std. Case management Active search of cases with

standard case definition Ensure safe water supply Inform State authority and ask

for help SOS IEC Documentation Feedback

3. Viral hepatitis 2 cases or more ofjaundice from onegeographical area.

District Nodal Officer Verifies the information from Medical Officer PHC/CHC

118

Confirmation of the outbreakby data analysis

Analysis of laboratory sample if any. RRT investigation to confirm

epidemic. Standard Case Management. Find out source of infection . Active search of cases. Ensure safe water supply. Stool samples for virus isolation. Serological investigation. Active search for 2nd/3rd trimester

cases with jaundice and keep them under observation with referral to Medical college hospital SOS.

Investigation of water Treatment Plant/ pipeline Leakages.

Inform State authority and ask for help SOS IEC Documentation Feedback

4. Measles Even a singlesuspected case

District Nodal Officer Verifies the information from Medical Officer PHC/CHC

Confirmation of the outbreak by data analysis


epidemic. Ring immunization and

effective containment. Send samples to reference

laboratory. Standard management of complicated

cases. IEC Vitamin A prophylaxis Feedback

6. JapaneseEncephelitis

Even a singlesuspected case.

District Nodal Officer Verifies the information from Medical OfficerPHC/CHC

Confirmation of the outbreak by data analysis

Analysis of laboratory sample if any.

119

RRT investigation to confirm epidemic.

Clinical confirmation. Standard case management. Active search of cases with standard

case definition. Vector surveillance and control. IEC Vaccination as a preventive

measure. Subsequently inform to higher

authority and ask for help sos. Laboratory specimen to reference

laboratory for Virus Isolation. Sero-diagnosis IEC Documentation Feedback

7. DF/DHF Even a single caseof suspectedDF/DHF from acommunity of 1000population.

District Nodal Officer Verifies theinformation from Medical OfficerPHC/CHC

Confirmation of the outbreak by dataanalysis


epidemic. Standard management of complicated

cases. Active search of cases with standard

case definition. Intensified Vector surveillance house-

tohouse Foggy/spraying if needed. IEC Empty the coolers, vessels and keep

them dry for 24 hours at least once in a week.

Sero-diagnosis IEC Documentation Feedback.

8. Malaria Even single caseis found malaria+ ve in an area

District Nodal Officer Verifies the information from Medical OfficerPHC/CHC

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where malariawas not presentfor minimumthree months.SPR rise morethan double overlast threemonths.Single deathfrom malaria(clinical/microscopically).Single PF caseof indigenousorigin.


Analysis of laboratory sample if any. RRT investigation to confirm epidemic Mass survey for fever cases. Microscopic examination within 24

hours Start CRT to all fever cases/all

contacts of + ve cases and all migratory population. (in case of single PF case of indigenous origin is found)

Focal spraying with synthetic pyrethyroid

Fogging daily X 3 days followed byBiweekly for 3 weeks.

Larvicidal application Elimination of mosquitogenic places

by tempting of water tables, land filling, chanalizing the drains.

Activate DDC/FTD Involve local bodies and community

by IEC. Daily surveillance for 3 to 4 weeks.

9. Unusualsyndromescausing death orhospital admission

Hospitalization ordeath of minimumtwo cases of similarillness from samegeographical area.

District Nodal Officer Verifies theinformation from Medical OfficerPHC/CHC



epidemic Basic Life Support and emergency

medical care. Refer to appropriate hospital. Active search of case. Autopsy and preservation of body

fluid and tissues of vital organs for laboratory diagnosis.

IEC to avoid panic. Reporting to the higher authority. Documentation Feedback.

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ANNEXURESFor

Outbreak InvestigationAnd Response

1. RUMOUR REGISTER2. SAMPLE INITIAL REPORT3. LINE LISTING OF CASES4. INTERIM OUTBREAK REPORT

HANDOUT -1

RUMOUR REGISTERRecord verbal or written information from lay reporters (community representatives,Anganwadi workers, teachers) about suspected outbreaks, rumours, or reports ofunexplained events.

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Date of notification

Suspected Disease(signs and symptoms if diagnosis

is not available)

Location No. of cases

Date of 1st

caseNo: of deaths Treatment

centersComments

HANDOUT -2

SAMPLE INITIAL REPORT(For outbreaks caused by water borne diseases)

(to be submitted within a day of the first team reaching the outbreak site)

1. Name of the affected village/town/city

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2. Name of the reporting center

Sub-centre / PHC / RH / CH / GH / Corpn. Hosp.

3. Block / Districts

4. Population of the affected town / area

5. Date of onset of outbreak

6. Date of reporting

7. Name of the Informant

8. Total attacks reported till date

9. Total deaths reported till date

10. Main symptoms of the patients

11. Presumptive / Final Diagnosis

12. Probable cause of the outbreak

13. Spot map

14. Water supply information

Water supply scheme / wells / bore-wells / others

General / Private

15. Date of stool samples collection (during the outbreak)

16. Stock position

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17. Details

of any control

measures instituted:

Sr. No. Control Measures Action taken

1 Place of the treatment

2 No. of the attending staff (MO, Nurses)

3 Camp hospital opened, if yes details

4 Date of starting active surveillance

5 Chlorination of water sources started, if yes,details thereof

6 Water samples collected? If yes, detailsthereof.

Sr. No. Name of the medicine Approximate Stock

1 Furazolidine

2 Tetracycline

3 O.R.S. packets

4 Ringer’s lactate

5 I.V. Normal saline

6 IV sets

7 Bleaching Powder

8 Halogen tablets

9 Tab. Co-trimoxazole

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Date: Signing Authority

Similar ones for Vaccine preventable diseases and Vector borne disease may be made. In the former, details of immunization status need to be included, while in thelatter, details of vector control measures need to be included.

HANDOUT -3

LINE LISTING OF CASES

no. name age sex fathers name

address date ofonset ofillness

symptoms &signs

treatmentreceived

lab reports

outcome exposure torisk factor

comments

Key to the formNo: serial numberName: of all the suspected casesAge: if there are small children involved, then better to record the age in months for ALLFather’s name: if identification is a problem through name onlyAddress: as detailed as possible so that later there is no problem while mappingDate of onset of symptoms: as accurate as possible as this gives an idea of the incubation period.Symptoms and signs: list the common symptoms and signs in each column. It should be filled as yes and noTreatment received: the details as well as the place at which it was received. Details include the medicines receivedLab reports: the details as and when they are available. Till then, the samples taken should be filled into this columnOutcome: whether the person is alive and well or whether the person is dead or whether the person is still sickExposure to risk factors: Initially this may not be clear, but as risk factors are identified, exposure to them needs to be checked.This may necessitate going back to the initial cases and checking.Comments: any comments related to the outbreak

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HANDOUT -4

INTERIM OUTBREAK REPORT(FOR OUTBREAKS DUE TO WATER BORNE DISEASES)

(Report to be submitted by RRT within 7 days of reaching the spot)

1. RRT members

2. Name of the affected towns / villages / Blocks / Districts

3. Name of the sub-center(s) / PHC(s) affected

4. Is it a high-risk area?

5. Details of staffing in the affected institutions, including vacancy positions

Prior to the outbreak, existing situation now.

6. Details of the geographic location of the area, preferably supported with

a map, giving details of

the population – both affected and not affectedthe institutions and distances involvedthe water sources etcany other risk factors

7. Date of onset of first case

8. Date of reporting of first case

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9. Date of onset of last case reported

10. Date of detection of last case reported.

11. How was the outbreak detected?

11.Main symptoms and signs

12. Epidemic curve

13. Details of possible transmission – preferably graphically.

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15. Probable diagnosis

16. Lab diagnosis

17. Information of Laboratory Examination

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23. Cause of the outbreak (Detail information of the reasons of water contamination)

24. Details of containment measures taken

25. Details of the mortality audit –

1. Name of the diseased :

2. Age : Sex :

3. Complete address :

4. Symptom :

5. Date of onset illness :

6. Treatment received from whom and where :

7. If admitted, and date and time of admission :

8. Date and time of onset of treatment :

9. Condition of the patient at the time of the

admission:

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10. Details of the treatment :

11. Date and time of death :

12. Place of death (Home / Hosp, etc.) :

13. Whether stool sample was taken ?

(If yes, result)

:

14. Medical Officer’s opinion :

Similar reports can be developed for the VPD and VBD.

Similar format can be used for the Final report.

HANDOUT -5REPORT WRITING

STEPS OF REPORT WRITING

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A standard report may contain up to 7 parts: Introduction

What is the problem you are investigating and why is it important? Background

What is already known about this and similar problems? What existing information and theories are you going to use to solve the problem?

ProcedureWhat experimental steps have you taken to solve the problem?

Experimental dataWhat raw data have you obtained?

Calculations and resultsHow did you transform the raw data into the data necessary to solve the problem? Show the calculations you performed on the data you collected.

ConclusionsWhat conclusions can you draw from your results? Discuss any new questions that were generated by your experiments.

ReferencesBibliographical citations of all published work from technical journals or books that you used in your study. If a theory or method is not your own, but was borrowed from another researcher’s work, you must acknowledge this by referring the reader to the paper or book in which you found the information.

Source: www.chemcollective.org/oldlab/ report .doc

http://www.chemcollective.org/oldlab/report.doc

Introduction

A report is a presentation of facts and findings, usually as a basis forrecommendations; written for a specific readership, and probably intended to be kept as a record.

When some people write a report, that's all they do: write. But the really successful writers only spend part of their time doing this, and then only towards the end. Before that, they are planning their report - thinking about its purpose, and who is going to read it; deciding what to put in it, and fitting it into shape. And even when they're finally writing it, they'll probably spend just as much time thinking about how best to present their ideas, as actually putting them onto paper.

This guide draws on the experience of such writers, and describes their step-by-step approach, the six stages being:

Purpose and readerMaterials and structureStyle and presentation

The guide has been devised for you to use as a memory aid once you are back at your desk, and working on your next report. We hope that you'll find it helpful, and that you -and your readers - will benefit.

Purpose and Reader

Experienced writers always allow plenty of time for these - the first two stages in report writing, even when they are working against the clock. They know that once these are clear in their minds, they'll save themselves hours of work and worry later on.

1 Defining the purpose

First, the purpose - the major aim - the reason why you are writing the report at all. This will determine what kind of report you write.

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a) Factual reportFor example, it may be to inform - when, say, there's been an accident, or a new programme of work. What's needed here is a factual report - a straightforward statement of the facts - to give people an accurate record.

b) Instructional reportOr, it may be to explain - for example, when some change is introduced, like a revised appraisal system, or a new job evaluation scheme. Here you write an instructional report - a step-by-step description - to tell people about the new procedures.

c) Leading reportLastly, it may be to persuade - when you are trying to sell your ideas. This kind is usually called a 'leading' report, because you are leading the reader towards making a decision - the one you want him or her to make.

Once the major aim has been defined in this way, subsidiary aims will fall into place -thus, we inform in order to explain, and inform and explain in order to persuade. And usually the result will be a leading report - which is often the most difficult to write, because it has to motivate the reader to do something at the end.

2. Identifying the reader

But who is the reader? What do we really know about them? Often, they are just a dim and shadowy figure in the mind, but we can usually get a clearer picture by asking three questions:

a) What does the reader know?Two common mistakes in report writing are to overestimate a reader's knowledge-and blind them with science, or to underestimate it - and bore them to tears. We must always try to discover how much the reader knows already, so that we can communicate at their level of knowledge.

b) What are the reader's attitudes?However good our ideas, they may get thrown out if we don't take account of these, the reader’s special interests, likes, and dislikes. The truth has many faces, and it is only sensible to feature the one most likely to appeal to them.

c) What does the reader really want?The reader is rarely a passive recipient of our report, to be swayed this way and that by our arguments. We'll need to find out just what their hopes and expectations are. Then we shall know what we're up against, and can prepare our case accordingly.

Sometimes, it is difficult to answer these questions, especially when writing for a varied readership. In such cases, aim for the important reader - that is, the most important to you - but without offending others. Some are probably only on the distribution list anyway for reasons of prestige or

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courtesy, or because no-one remembered to cross them off. They will probably be quite happy just to read the opening summary (see p.7).

3 Setting the objectiveMatching the purpose to the reader, we are now ready to set our objective. In other words, what do we want the reader to think and do after reading our report? Here is an example:To persuade the managing director to authorize a proposed system of flexible working hours.

Notice the words 'to persuade' and 'to authorize'. They show that we must produce a logical and consistent case: one that will spur our reader to positive action. Also, once we have set the objective, we can usually anticipate the likely problems in meeting it e.g.:

a) KnowledgeThe managing director is a busy man, and has never heard of flexible working hours. We’ll need to give him ample background information, and define any technical terms as we go along.

b) AttitudesHe is a stickler for discipline and good timekeeping. We'll have to convince him that the scheme won't be a licence for lateness, but that, on the contrary, timekeeping might actually improve.

c) WantsAccording to the grapevine, he is worried just now about rising costs. So we'll need to stress how flexible working hours would actually save him money, even if this means playing down other benefits.

Arriving at an objective like this is the most important step in writing any report. Sometimes the process will even show that a report is not necessary at all, and that the objective can best be met in some other way - in which case, you will have saved yourself a great deal of time and trouble.

Materials and structure

Most writers imagine that their report will be the major event in the reader's day, when, in reality, the poor fellow is awash with reading matter, drowning in facts, figures, and opinions. What he wants is easily-digested information, and then only enough to help him reach a decision. So the content of our report, and its structure, must be very carefully planned.

1 Selecting our material

The two golden rules to follow when deciding what to put into a report are:

a) Simplify, and be ruthless about it. Reject the irrelevant, agonize over the doubtful, and make sure you've got the essential.

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b) Justify your conclusions with facts, and state their sources. Build the facts into a logical and consistent case, so as to lead the reader to the same conclusions as your own.

2 Planning the structureThe facts themselves should therefore be a set of directions, which will lead and guide your reader along a route. This route has to be planned before you write your report, perhaps as follows:

Turn a large sheet of paper sideways, and work across it. Work horizontally, so that you can see the whole plan of your report at one time (see p.6).

First, divide it into major sections. Every subject can be broken down in this way, and the headings will probably become the headings in your report.

Make a list under each heading of all the points you would like to mention. Note the information that you'll need to support them.

Now mark the most important points, the essential steps in your reasoning.

Next, mark the least important ones, points your reader would find irrelevant. These you will probably reject.

The points that remain-the unmarked ones, are the 'doubtful'. Some you may want to use as examples, or to include in the appendices. But some of these also you'll reject.

Lastly, arrange the points in a final, logical sequence, so as to meet your objective. Some people write them out on scraps of paper at this stage, and shift them around until they get the order right.

A plan like this will show you what information you'll need for the body of the report, and what should go in the appendices. Once written, you draw out your conclusions and add your recommendations. And last of all, you add your title page, summary, contents list, and introduction. These eight items make up the conventional structure of a report, dealt with in more detail below.

3 Rules and guidelines

The following rules and guidelines relate to the conventional structure of a report. Some organizations lay down their own ('House style').

a) Title pageThis normally carries the title, sub-title if any, date, author's name and position, and distribution list. It may also carry a reference number or other classification (eg, confidential). But don't overcrowd the page: a clear, simple layout is always the best.

b) Summary

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A necessity if the report is a long one. It gives busy people the gist of the report without their having to read it all; but if attractively written, it may whet their appetite, and stimulate them to read the whole thing.

c) Contents listThe contents of short reports may be shown on the title page - or not at all. More extensive ones should always have a separate page, listing the major sections or chapters, sub-sections if any, and appendices, and giving their page numbers. It should be laid out clearly so as to show the relationship between them.

d) IntroductionThis gives the background to the report, and shows why it was necessary. It usually states the objective of the report (in formal terms), who called for it, and the scope and treatment. The shorter it is, the better.

e) Body of the reportThis contains your detailed facts and findings, shows how they were arrived at, and indicates the inferences to be drawn from them, all in accordance with your horizontal plan (p.5).

f) ConclusionsHere you draw out the main points of your report and present a considered judgment on them.

g) RecommendationsFinally, set down any recommendations, relating them clearly to what has gone before. In a good report, the reader is carried along by the argument, so that by the time here aches the end, he'll need no further convincing.

h) AppendicesSome reports need detailed supporting information, or perhaps information that only some readers need. All this goes in the appendices.

In some cases you may also need to include:

j) Bibliography and/or ReferencesThis lists both the books and articles consulted as a basis for the report, or those you want to suggest as further reading - or both. Make clear which they are.

k) Glossary or NomenclatureThis can be a help if your readers include non-experts as well as experts. When writing on a specialist subject for non-experts alone, define any technical terms as you go along.

Style and presentation

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Having dealt with the four essential stages in planning our report, we can now look at the two essential aspects of writing it.

1 StyleThis is how you write - how any individual writes, so as to convey your thoughts to other people. But problems may arise, especially if you try to evaluate each word or sentence as you write it. 'That's silly,' you say, or, 'That won't work,' and you end up by blocking the natural expression of your ideas.

To overcome these problems:

a) Write the first draft to yourself. Just as it comes. Don't evaluate what you are writing: simply break the spell of that blank, white sheet of paper.

b) Then edit your draft, reading it through the eyes of your reader. In particular:

Clear up any clichés and obvious ambiguities, e.g., '. . . the flooding was caused by the liquidation of the contractors working on the sewage system.'

Substitute short, simple words where appropriate, e.g., 'start' for commencement', and ‘end' for 'termination'.

Choose words familiar to your reader. Technical terms are a useful shorthand to use with fellow specialists, but simply cloud the issue for anyone else.

Use active, rather than passive verbs, eg, 'The Board has approved this project,' rather than 'Approval has been given by the Board for this project.' This is a contentious issue– most scientific reports tend to be written using the passive form. Ask about the'House Style' if in doubt.

Follow these rules, and your problems will diminish. In fact, choose the right words, and you’ll find that they have a happy knack of arranging themselves.

2 PresentationsYou may need to use tables, graphs, bar charts, or other diagrams. This is a subject in itself, so ask your local librarian for some helpful books. (The standard work, but expensive, is Diagrams, by A. Lockwood, published by Studio Vista.)

Also, remember the old journalistic principle: solid blocks of type weary the eye. Set your report out generously. Use wide margins; space out paragraphs; and indent subheadings. It will make all the difference.

Helpful books139

General reference material

Get to know your local reference library and the librarians in charge. They are used to handling every type of enquiry, and will help you to draw on a wealth of immediately available reference material, in the shape of encyclopaedias, dictionaries, directories, handbooks, year-books, statistical returns, abstracts, etc. They are also able to draw on the help of other, specialist, libraries and information services, many of which are not known to the general public.

Books on report writing

For anyone wanting to know more about the actual job of report writing, we recommend the following:

1. How to write reports John Mitchell. (Fontana/Collins)

2. Report writing A. E. Derbyshire. (Edward Arnold)

3. Writing technical reports Bruce M. Cooper. (Pelican)

4. The technique of clear writing Robert Gunning. (McGraw-Hill)

A writer's friends

There are also a number of books which should be by your side whenever you write a report. We have limited the list below to those in paperback or inexpensive hardback editions:

1.Chambers Twentieth Century Dictionary or

2.The Concise Oxford Dictionary (or ideally both)

3.Roget's Thesaurus of English Words and Phrases (Longmans)

4.Authors' and Printers' Dictionary F. Howard Collins. (OUP)

5.The Complete Plain Words Sir Ernest Gowers. (Penguin)

6.Fowler's Modern English Usage (OUP)

7.Usage and Abusage - a guide to good English Eric Partridge. (Penguin)

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HANDOUT -6

How to Review an Article

Guidelines for ReviewingHere are nine things you should consider as you examine the manuscript and write your review:

Look for the "intellectual plot-line" of the article. You can do this from first skimming through the manuscript and then giving it a once-over read. As you do this, ask the five major questions that are central to the research review process:

1. What do the researchers want to find out?2. Why is that important to investigate or understand?3. How are the researchers investigating this? Are their research methods appropriate and

adequate to the task?4. What do they claim to have found out? Are the findings clearly stated?5. How does this advance knowledge in the field? How well do the researchers place their

findings within the context of ongoing scholarly inquiry about this topic?

Look at the organization of the article. Can you find answers to the above questions quickly and easily? Can you trace the logic of investigation consistently from the opening paragraphs to the conclusion?

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Then go back to the opening paragraphs of the article. Are the research questions specifically stated? Is it clear what the authors want to find out? Do they make the case that this is an important area for research inquiry?

The next section is usually a review of the existing research literature on this topic. Do the authors present a convincing line of argument here--or does it appear that they are just name-dropping (citing sources that may be important, without a clear underlying logic for how they may be important)? Do the authors focus on ideas, or merely on discrete facts or findings? Have they given sufficient attention to theory--the cumulative attempts at prior explanations for the questions they are investigating? Are the research questions or hypotheses clearly derivative of the theory and the literature review? In short: How well do the authors set the stage for the research problem they are reporting?

The methods and procedures section is usually next; and this is where neophyte reviewers often start (unwisely) to sharpen their knives. The selection of methods by which the researchers collect data always involve compromises, and there are few studies that cannot be criticized for errors of commission or omission in terms of textbook criteria for research design and data collection procedures. You could focus on three questions here:

1. Do the authors clearly describe their research strategies? Do they present sufficient detail about the sample from which they have collected data; the operationalization of measures they have attempted to employ; and the adequacy of these measures in terms of external and internal validity? In addition, there should be no surprises here: The measures should be clearly matched to the research questions or the hypotheses.

2. Are their choices of methods adequate to find out what they want to find out in this study? Would other methods provide a substantial improvement; if so, would employing these methods be feasible or practical?

3. Do they provide some justification for the methods they have chosen? Does this appear to be adequate?

The section presenting research results is surely the heart of the article--though not its soul (which the reader should find in the opening paragraphs and in the discussion section). Reviewers might consider four questions here:

1. Does the results section tell a story--taking the reader from the research questions posed earlier to their answers in the data? Is the logic clear?

2. Are the tables and figures clear and succinct? Can they be "read" easily for major findings by themselves, or should there be additional information provided? Are the authors' tables consistent with the format of currently accepted norms regarding data presentation?

3. Do the authors present too many tables or figures in the form of undigested findings? Are all of them necessary in order to tell the story of this research inquiry; or can some be combined? Remember that tables and figures are very expensive (from the standpoint of the journal) and that undigested data obscure rather than advance the cumulative development of knowledge in a field.

4. Are the results presented both statistically and substantively meaningful? Have the authors stayed within the bounds of the results their data will support?

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The discussion section is where the authors can give flight to their findings, so that they soar into the heights of cumulative knowledge development about this topic--or crash into the depths of their CV's, with few other scholars ever citing their findings. Of course few research reports will ever be cited as cornerstones to the development of knowledge about any topic; but your review should encourage authors to aspire to these heights. Consider the following as you evaluate their discussion section:

1. Do the authors present here a concise and accurate summary of their major findings? Does their interpretation fairly represent the data as presented earlier in the article?

2. Do they attempt to integrate these findings in the context of a broader scholarly debate about these issues? Specifically: Do they integrate their findings with the research literature they presented earlier in their article--do they bring the findings back to the previous literature reviewed?

3. Have they gone beyond presenting facts--data--and made an effort to present explanations--understanding? Have they responded to the conceptual or theoretical problems that were raised in the introduction? This is how theory is developed.

4. Do the authors thoughtfully address the limitations of their study?

The writing style is important. Consider the three guidelines for successful communication--to be clear, concise, and correct---and whether the authors have achieved it:

1. Is the writing clear? Do the authors communicate their ideas using direct, straightforward, and unambiguous words and phrases? Have they avoided jargon (statistical or conceptual) that would interfere with the communication of their procedures or ideas?

2. Is the writing concise? Are too many words or paragraphs or sections used to present what could be communicated more simply?

3. Is the writing correct? Too may promising scientists have only a rudimentary grasp of grammar and punctuation that result in meandering commas, clauses in complex sentences that are struggling to find their verbs, and adjectives or even nouns that remain quite ambiguous about their antecedents in the sentence. These are not merely technical issues of grammar to be somehow dealt with by a copy-editor down the line. Rather they involve the successful communication of a set of ideas to an audience; and this is the basis of scholarship today.

Your evaluation to the editor: Should this paper be (a) rejected for this journal? (b) or does it show sufficient promise for revision, in ways that you have clearly demonstrated in your review, to encourage the authors to invest weeks and months in revision for this journal?

Your bottom-line advice to the editor is crucial. Make a decision; state it clearly (in your confidential remarks to the editor on the page provided).

Remember that only a few of the articles submitted to a journal will result in publication. Rates vary from 5% to 25% of initial submissions.

Some reasons to reject a manuscript:

(a) The research questions have already been addressed in prior studies; (b) The data have been collected in such a way as to preclude useful investigation;

143

(c) The manuscript is not ready for publication--incomplete, improper format, or error-ridden.

Most rejected articles do find a home in other journals. Don't tease authors with hopes for publication in this Journal if you feel it is not likely.

Good Reviews and Bad ReviewsA good review is supportive, constructive, thoughtful, and fair. It identifies both strengths and weaknesses, and offers concrete suggestions for improvements. It acknowledges the reviewer's biases where appropriate, and justifies the reviewer's conclusions.

A bad review is superficial, nasty, petty, self-serving, or arrogant. It indulges the reviewer's biases with no justification. It focuses exclusively on weaknesses and offers no specific suggestions for improvement.

Source: How to Review a Journal Article:Suggestions for First-Time Reviewers and Reminders for Seasoned ExpertsBy Vern L. Bengtson, University of Southern California,and Shelley M. MacDermid, Purdue Universityhttp://www.ncfr.org/journals/marriage_family/guidelines.asp

TABLE 1

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Criteria for manuscript review

1. Scientific quality of the work_ Are the methods appropriate and presented in sufficient detail to allow the results to be repeated?_ Are the data adequate to support the conclusions?2. Presentations_ Writing: Is it clear, concise, and in good English?_ Title: Is it specific and does it reflect the content of the manuscript?_ Abstract: Is it brief and does it indicate the purpose of the work, what was done, what was found, and the significance?_ Figures: Are they justified? Are they sharp, with lettering proportionate to the size of the figure? Are there legends to explain the figures?_ Tables: Can they be simplified or condensed? Should any be omitted?_ Trade names, abbreviations, symbols: Are these misused?3. Research violations_ Are there violations of the Guiding Principles in the Care and Use of Laboratory Animals?_ If the research involved human subjects, were the studies performed in accordance with the Declaration of Helsinki?If you have concerns about the welfare of animal or human subjects used by the authors, include written comments to the editor.4. Rating_ Assign a rating on the reviewer form; rank the manuscript relative to other work in the same field.5. Confidential comments_ Provide comments regarding the novelty and significance of the manuscript._ Provide a recommendation about the manuscript’s suitability for publication in the journal; these comments will not be returned tothe author(s).6. Comments for authors_ On the reviewer form, provide specific comments, preferably numbered, on the design, presentation of data, results, and discussion.DO NOT include recommendations for publication on the second page._ Please be certain that your comments to the author(s) are consistent with your rating recommendation.7. Privileged document_ This manuscript is a privileged communication; the data and findings are the exclusive property of the author(s) and should not bedisclosed to others who might use this information in their research.

WRITE A BASIC ARTICLE REVIEW

PREPARATION Look at the questions below. You'll answer these in the Impressions Table in Step 4. Keep them in mind as you read articles and you will increase the number of reviews your write:

1. Was the article clearly written?2. Was the argument/message easily understood? 3. Was it an interesting read? 4. How did the spelling and grammar mistakes affect the read? 5. What was their readability speed or flow characteristic? 6. Did the author successfully introduce some sharp, witty or clever bits? 7. How accurate was the content? 8. How useful was this content to you?

Of course, these questions pre-suppose some expertise, but the standard is not so tall that well meaning readers should avoid doing reviews. Many of us are innately equipped to spot poor grammar, spelling and punctuation; to detect jerky flow and difficult-to-understand expressions; to recognize wit or the author's skill with metaphors and similes, both of which add interest and insight to the writing. We may be less skilled to detect inaccuracies, yet the last question, usefulness, often overcomes this insofar as a fair review is concerned.

STEP-BY-STEP INSTRUCTIONSThese instructions begin with the creation of a document that will house your review as you build it. Any capable word processor is suitable (there's a free word processor at Google Docs with the further benefit of on line storage and access). The instructions presuppose that you have an interest in the article's topic, your motivation for reviewing it.

1. Step One - Open a Review Document

Open a new document and position its window to capture your keystrokes. Save the empty document with an appropriate name, like Review-PricingTips.

Scan the chosen article and author's profile to identify and enter the following in your review window;

The title (i.e. Pricing Tips) The author's stated role (i.e. Small Business Coach) if available The author's published or username for this article (i.e. Peter Baskerville)

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2. Step Two - 1st Read "Absorbed" You may have already done Step Two and now wish to review the article because it's worth it. On the other hand, you've not yet read the article. However, you suspect the article is going to be good and you read it for the first time as the interested and absorbed reader that you are. The impressions you gain on the 1 st read will help you complete the table we offer in Step 4. Read now to enjoy and to learn because you are interested in the topic and want to benefit from this author's work on the subject.

3. Step Three - 2nd Read "Detached" The 2nd read will be approached in a different manner. You'll remain "detached," continually asking questions of the author as an arms-length observer. The eight primary questions are listed above, under Preparation. Reading "detached" is not always easy because a skillful writer continually draws you in. Resist! If you do it often enough, you'll soon figure out how to switch from "absorbed" reader for enjoyment purposes to "detached" reader for review purposes. In fact, with time you may become capable of simultaneous absorbed and detached reading, which is the standard for newspaper and movie critics who only get one pass.

4. Step Four - Theme and ImpressionsBased on your 1st and 2nd readings, write in your document a single sentence that describes the author's central theme, argument or message. Then look at the Impressions Table below. For each row determine the word/phrase that you feel best answers the question. Take note of the Question Number (A to H) with the corresponding answer grade (1 to 4).

IMPRESSIONS TABLE

Excellent

1

Great

2

Good

3

Average

4

(A) Was it clearly written and easily understood?

Crystal Clear

Easily Understood

Orderly

Sufficient

(B) Was it an interesting read?

Invigorating

Absorbing

Interesting

Satisfying

(C) How did the spelling and grammar mistakes affect the read?

Undetectable

Only one

Evident but OK

Should be corrected

(D) What was its readability speed or

Graceful

Polished

Smooth

Acceptable

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flow?

(E) Was it sharp, witty or clever?

Effervescent

Delightful

Pleasant

Adequate

(F) How accurate was the content?

Without fault

General Agreement

No issue

Some Questions

(G) How useful was the content to you?

Totally Relevant

Useful for many

Some useful points

One thing of value

(H) OVERALL

Highly Recommend

Meritorious

Worthwhile

Acceptable

5. Step Five - Copy & PasteCopy & paste the complete standard phrases (those between the red cut marks) list below into your document. Using your question and answer notes, delete the question headers as well as the three answers responses that you did not select. --------------------------- -------------------------------- (A) UNDERSTOOD 1 - EXCELLENT – The author’s line of reasoning was crystal clear2 - GREAT – The author’s position and argument was easily understood3 - GOOD – The author presented an orderly explanation of the concepts4 - AVERAGE – The author presented sufficient information to understand the concepts (B) INTERESTING 1 - EXCELLENT – and it was an invigorating read.2 - GREAT – and it was an absorbing read.3 - GOOD – and it was a interesting read.4 - AVERAGE – and it was a satisfying read. (C) SPELLING AND GRAMMAR

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1 - EXCELLENT – Moreover, if there were any spelling or grammar mistakes they were undetectable to me.2 - GREAT – Moreover, it was well constructed and presented apart from one [spelling/grammar] mistake.3 - GOOD – Moreover, while there were some [spelling/grammar] mistakes they did not detract significantly from the reading experience.4 - AVERAGE –. However, I believe that the spelling and grammar should be corrected. (D) SPEED1 - EXCELLENT – [Author's surname]’s engaged a graceful writing style2 - GREAT – [Author's surname]’s engaged a polished writing style3 - GOOD – [Author's surname] engaged a smooth writing style4 - AVERAGE – [Author's surname]'s writing style was acceptable (E) CLEVER1 - EXCELLENT – with the [sharp/clever/witty/graphical] inclusions bringing a real effervescence to the reading experience.2 - GREAT - with the [sharp/clever/witty/graphical] inclusions making for a delightful reading experience.3 - GOOD – with the [sharp/clever/witty/graphical] inclusions adding significantly to the reader interest.4 - AVERAGE - with the [sharp/clever/witty/graphical] inclusions being satisfactorily handled. (F) ACCURATE1 - EXCELLENT – I am [very, reasonably, quite] knowledgeable about this subject and believe that the content was without fault.2 - GREAT – I am [very, reasonably, quite] knowledgeable about this subject and I am in general agreement with all the Author’s stated positions.3 - GOOD – I am [very, reasonably, quite] knowledgeable about this subject and find no issue with the content.4 - AVERAGE – I am [very, reasonably, quite] knowledgeable about this subject and some question remain concerning some of the Author’s statements. (G) USEFUL1 - EXCELLENT – [and/but] it was totally relevant and applicable to me.2 - GREAT – [and/but] I believe that it would be very useful for many that are interested in this topic. 3 - GOOD – [and/but] the author made some good points that others might find useful.4 - AVERAGE – [and/but] the author makes a good point about [.............]. (H) OVERALL 1 - EXCELLENT – Overall, I rate this article as a brilliant read that I would highly recommend to my friends.2 - GREAT - Overall, I would rate this article as a great read of high merit.3 - GOOD – Overall, I would rate this article as a good and worthwhile read.4 - AVERAGE – Overall, I would rate this article as an acceptable read. ---------------------- ---------------------------

6. Step Five - Compile: Complete/Remove/Make/Link/Adjust Now turn the individual components of an article review into a complete paragraph by doing the following:

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Complete the opening sentence "This article titled '[Article Title], written by the [Author's stated role] [Author's published name or username], sets out to show [Central theme, argument or message]

Remove the NUMBER and GRADE from the front of the 'standard phrase' Make the applicable choice in the [square brackets] when asked Link the 'standard phrases together to form sentences and then complete the paragraph Adjust the grammar and phrasing to suit your style of expression (if required)

7. Final Step - Place and Publish

Source: http://knol.google.com/k/peter-baskerville/how-to-quickly-write-a-basic-article/14j3i4hyjvi88/27#

HANDOUT -7

COMMUNITY A community can be thought of in relation to common interests, in which groups

share certain goals, objectives, roles, priorities or views in common. This might be based on common geographic location, or social, cultural or

religious affiliations.

Types of Communities Communities can be classified as:

ƒ Geographic (an urban mass; scattered rural dwellings; temporary homes built alongside railroad tracks.)

ƒ Religious/ethnic/political ƒ Socio-economic (caste/class)

ACTIVITY – 1Understanding the community

To do this you must: Identify opinion leaders and have informal discussions with them and with street children.

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http://knol.google.com/k/peter-baskerville/how-to-quickly-write-a-basic-article/14j3i4hyjvi88/27#

Get to know the profile of the community to identify any special features which will influence their involvement.

Find out how they feel about the activities you want to introduce. Find out if they agree with the proposals. Determine any conflicting interests.

Objective of the activity:By the end of this session, participants will be able to Understanding the community.

Exercise is taken from a WHO module in which the investigator wants to Work With Street Children regarding substance Use, Sexual and Reproductive Health including HIV/AIDS and STDs.

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Learning ActivityUnderstanding the community.The lemon game.With the help of a facilitator or trainer:

Obtain lemons or any available fruits and put them in a basket. Each participant must pick a lemon from the basket and look at it very briefly (first picking). Each participant must then put the lemon back into the basket. Each participant must try to pick their lemon from the basket and look at it a little longer than the

first time (second picking). Each participant should put the lemon back into the basket. Each participant must pick his/her lemon from the basket (third picking). By the ‘third picking’ each participant must be able to identify his/her lemon.

The facilitator will then ask those who were not able to identify their lemons to explain why theyfailed to do so. Afterwards, the facilitator will ask those who identified their lemons to explainwhy it was easier for them to pick out their lemon.

The facilitator or trainer will conclude with an explanation which is offered in the trainer tipsregarding the learning points of this game.

To understand the community you must exercise patience and get to know thecommunity well by making several contacts.

Field visit.

Conduct an informal visit to a potential community that you might work with such as shopOwners, government officials and street children. Ask them the following questions:

Have children lived or worked on the streets during other times in the history of yourcommunity?

At what age does the community believe that children should begin earning? At what ageare they expected to live away from their parents? Is the age different for girls and boys?

What are the major religions in the community? What are their beliefs about children,poverty, suffering, and helping others?

What religious beliefs do street children in your community hold? Do they participate inreligious ceremonies, rituals or festivals?

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What does the community think about substance use? How many adults use substances ofsome kind?

What does the community think about sexual and reproductive health and HIV/AIDS/STDs among street children? Do they think street children should be helped?

What activities do members of the community think are appropriate for boys and girls? Do people in the community feel differently towards street girls and street boys?

What are the major ethnic groups in the community? What are their views on workingchildren, on families, on substances, and reproductive health?

How does the community view people who work with street children? How does the local government view street children and those who work with them? Do

government officials feel any responsibility to become involved with street children? Are there laws that prevent children from living or working on the streets? Are there laws

that prevent or restrict street educators from working with street children? Are there international development agencies in your area? How does the community view

these agencies?

Use this information as a basis to approach and work with the community in order to avoid a conflict of interest.

Source: Page 4-5 department of mental health and substance dependence Geneva, Switzerland working with street children module 9involving the community a training package on substance use, sexual and reproductive health including HIV/aids and stds world health organization mental health determinants and populations department of mental health and substance dependence Geneva, Switzerland

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