Developing a protocol for a descriptive epidemiologic study

Talamo

ILARIA CASETTAFERRARA

• Each study should have a written protocol

• A protocol is a document that states the reasoning behind and the design of a research project

Study protocol

To clarify the research question and define objectives

To plan the project in details before To check if the objectives can be achievedTo check the feasibility of the studyPrevents failure to collect crucial informationTo have a guideline and tool for the research

team To obtain approval of ethical committee(s)Application for fundsMakes it much easier to write article

STUDY PROTOCOL: WHY?

KnowledgeIdea, Hypothesis

Research question

Refine research question

PlanningPerforming the study

Data analysis Results, Interpretation

Dissemination

STUDY PROTOCOL Principal Components

Protocol presentation

Background and rationale

Objectives

Design and Methods

Data analysisEthical issuesReferences Budget

Look atGuidelines for

applicants!

STUDY PROTOCOL

All protocols can be divided into two main sections: (i) the problem to be investigated and (ii) the method of investigation.

Problem to be investigated1.Background (literature

review)/rationale2.Objectives

BACKGROUND and RATIONALE

• What is already known? Is there consensus? Is there controversy? Is there conclusive evidence? What remains to be answered?

• Why is the research important?• What kind of answer will the study provide? • What is the ultimate purpose that the

knowledge obtained from the study will serve?

Review the relevant literature

OBJECTIVES

MMain objective• Must be achieved• Dictates design and

methods

Secondary objectives• Of interest, but not

essential

• Logical and coherent• Feasible• Realistic, considering

local conditions• Defined in operational

terms that can be measured

• Relevant

Use action verbes : i.e. “To estimate…, To compare..., To verify..., To describe..., etc.

FINER - Criteria for a Good Research Question(Hulley)

• FeasibleAffordable in time and moneyManageable in scope. Appropriate skills and expertise of the group

• Interesting

• NovelConfirms or refutes previous findingsExtends previous findingsProvides new findings

• Ethical• Relevant

To scientific knowledgeTo clinical and health policyTo future research directions

STUDY PROTOCOL- MethodsAll protocols can be divided into two main sections: (i) the problem to be investigated and (ii) the method of investigation.

1. Study design2. Study population3. Diagnostic criteria4. Case definition5. Case collection and ascertainment6. Data Collection

STUDY DESIGN and METHODS

Which is the best study design?*“The question being asked determines the appropriate research architecture, strategy, and tactics to be used”

*This is quoted from the accompanying editorial:Sackett DL, Wennberg JE. Choosing the best research design for each question. Editorial. BMJ 1997;315:1636

Timeframe of Studies

Prospective

time

Retrospective

time

Cross-sectional

STUDY PROTOCOL- Methods

1. Study design2. Study population 3. Diagnostic criteria4. Case definition5. Case collection and ascertainment6. Data Collection

Defining the population at risk of disease

Classifying and categorizing disease

Deciding what constitutes a case of disease in a study

Denominator

Diagnostic criteria

Inclusion and exclusion criteria

METHODS

Case d

efi

nit

ion

METHODSPopulation at risk

• Geographical bundaries (study area-setting)

• Specific populations– Demographic – Others

(occupational, exposures,…)

• Population sample (sampling procedure)

Appropriate for study objectives

• Study area

• Population

• Temporal boundaries

Define the size, characteristics, health organization

Total, by sex and age groups (Census data)

• Incidence interval• Prevalence point

(period)

Defining the population at risk of disease ( denominator)

• The study area will be the province of Sassari, north-western Sardinia, with a surface of 4,282 Km2. It comprises 66 municipalities…The province population is 333,576 (163,104 men and 170,472 women), December 31, 2007.

• The Section of Neurology, University of Sassari, hosts the referral Centre for Epilepsy of northern Sardinia. Other relevant structures for medical care of adult epileptic patients in the study area are the Division of Neurology, sub-Health District Hospital of Ozieri, the Departments of Internal Medicine in sub-Health Districts of Sassari, Alghero and Ozieri. Few consultant neurologists practising for the National Health System (NHS) territorial services in the study area ……provide care to epileptic patients.

• Since year 2000, Sassari Health District has benefited from the Health Information System Unit (HISU) where health information is collected at population-based level into electronic datasets, including hospital discharge records and disease specific medical care fare exemptions.

Epilepsy in Sardinia, Insular Italy: A Population-Based Prevalence Study

• Diagnostic criteria may vary over time• Different level of diagnostic certainty• Definite diagnosis may require post-

mortem examination• Onset of the disease? • Lag time between onset and diagnosis

Case definition- problems

• Diagnostic Criteria

• Inclusion and exclusion criteria

deciding what constitutes a case of disease

The diagnosis of ALS will based on the first version of the El Escorial criteria. These criteria distinguish four levels of diagnostic certainty: definite, probable, possible, and suspected ALS. All the diagnostic levels will be considered for the calculation of incidence. Cases with progressive bulbar palsy (PBP), progressive muscular atrophy (PMA), and primary lateral sclerosis (PLS) well be included.Individuals under the age of 18 will be excluded to avoid misclassification of other motor neuron diseases of genetic origin, mimicking ALS. We will use MG to reclassify cases according to the revised El-Escorial criteria.

Modified from Logroscino et al, 2005

STUDY PROTOCOL- Methods

1. Study design2. Study population 3. Diagnostic criteria4. Case definition5. Case collection and ascertainment6. Data Collection

• Existing diagnoses (Hospital, Services, Drug prescription, Notification system, Registers, Discharge diagnoses, family doctors……)

• Direct contact survey

CASE COLLECTION and ASCERTAINMENT

Multiple sources of data

Prevalence study

Hospital records,

Outpatient services

EEG services

Laboratory for

AEDs assays

Discharge

diagnoses

Exemption codes

• How?

• By whom?

• Tools? Describe instruments used!Recording materials (Case Record Forms), Questionnaires , ..)

CASE and DATA COLLECTION

Data handling and processing

• Data coding• Data entry, data

quality control• Data analysis

• Confidentiality, anonymity

• Informed consent

• Data storage and protectionIncidence (mortality)

rate, Prevalence, 95% CIs, Variable-specific rates, Adjusted rate

Ethical issues

• Participating Collegues/Centers• Tasks of each participant/Center• Timetable, work plan, project milestones• Data Ownership• Publication policy• Resources-Budget• References• Additional material ( data collection instruments, questionnaires, consent form..)

Other aspects

COMMON PROBLEMS• Insufficient attention to literature • Failure to provide the proper context to frame

the research question. • Failure to cite relevant studies • Poor justification, failure to develop a

persuasive argument for the proposed research. • Poor description/poor methodology• Proposing more work than can be reasonably

done during the grant/study period• Too much detail on minor issues, but not

enough detail on major issues. • Too long / verbose or too short.