Definition and Scope Pharmacoepidemiology
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Transcript of Definition and Scope Pharmacoepidemiology
PharmacoepidemiologyDefinition and scopeKanav Khera Lecturer Dept of Pharmacy Practice
Definition and scope: Pharmacoepidemiology: Study of the use
and the effect of medicine in large number of people. OR Pharmacoepidemiology can be defined as the study of the therapeutic effect(s), risk and use of drugs, usually in large populations, using epidemiological methods and/or reasoning.
Epidemiology: Epidemiology Study of the relationships
between diseases or any other biological phenomenon and various factors (e.g. lifestyle, environment or social setting, individual traits, etc.) which can influence their frequency, distribution and evolution. Descriptive epidemiology, in which the
objective is to describe a population (e.g. drug utilization studies), Analytic epidemiology, in which the objective is to study the associations (causal or otherwise) that can exist, within a population, between the occurrence of an event and a given characteristic
Pharmacoepidemiology: Bridging b/w
clinical pharmacology and epidemiology Application of the principles of epidemiology to drug effect and drug use Better assessment of risk/benefit balance for the use of any particular drug in any particular patient Focus: Clinical Pharmacology: Drug effect in Individual Patient Drug Utilization: Drug usage pattern and appropriateness of drug use in groups Pharmacoepidemiology: Relation between drug exposure and health outcomes in
Adverse reactions Type A reactions: reactions tend to be common, dose-
related, predictable, and less serious. They can usually be treated by simply reducing the dose of the drug. They tend to occur in individuals who have one of three
characteristics. First, the individuals may have received more of a drug than is customarily required. Second, they may have received a conventional amount
of the drug, but they may metabolize or excrete the drug unusually slowly, leading to drug levels that are too high. Third, they may have normal drug levels, but for some
reason are overly sensitive to them.
Type B reactions: tend to be uncommon, not
related to dose, unpredictable, and potentially more serious. They usually require cessation of the drug. They
may be due to what are known as hypersensitivity reactions or immunologic reactions. Alternatively, Type B reactions may be some
other idiosyncratic reaction to the drug, either due to some inherited susceptibility (e.g., glucose-6-phosphate dehydrogenase deficiency) or due to some other mechanism. Regardless, Type B reactions are the more
difficult to predict or even detect, and represent the major focus of many pharmacoepidemiology
Origin and Evolution of Pharmacoepidemiology Pharmacotherapy 20th century
Use of drug inc-----ADR inc 1961 Maternal use of Thalidomide with
malformations (Limb reduction) in offspring -----Focus of detection , prevention and management of ADR--------- It began the era of Pharmacoepidemiology To Identify ADR----spontaneous reporting and
surveillance programs created e.g Grey baby syndrome with chloramphenicol \ Birth defect with Isotretetinoin
Drug re-introduce : when drug have unique benefit
and risk can be managed E.g Isotretinoin, cancer drugs etc. Drug utilization : Define as marketing , distribution , prescription and use of drug in a society with special emphasis on the resulting medical, social and economic consequences Drug utilization review ( DUR): define as authorized , structural and continuing program that review, analysis and interprets pattern of drug use against predetermined standards DUR studies focus on drugs and Aim of these
studies is to evaluate the appropriateness of the therapy using approved criteria and to develop
Aim of Pharmacoepidemiology Signal Generation: Most commonly
associated with ADR but also use to detect new applications E.g Minoxidil 1st indicated for hypertension but case report (signal generation) soon identified it causes hirsutism in a number of patients, side effect was investigated and now it is marketed for purpose mainly stimulation of hair growth Risk Quantification: of ADR often require
large sample size
Hypothesis testing: Require the use of comparison group to
determine whether there are difference in variable of interest (risk factor, trait, characteristic, drug exposed, or clinical conditions) Statistic method are used to assess whether the
observed difference could have occur by chance alone Conclusions about relation b/w exposure to a
drug and clinical event thus based on the ability to reject the null hypothesis, postulating that
Reasons to perform pharmacoepidemiology studies
Application of Pharmacoepidemiology Estimation of risk of drug use
Use in patient counseling Formulation of public health policy decision Formulation of therapeutic guidelines and
discovery of new indications Facilitation of pharmaco-economic evaluation
Pharmacoepidemiology in Practice The basic idea of pharmacoepidemiology is to
measure the source, diffusion, use, and effects of drugs in a population and to determine the frequency and distribution of drug use outcomes in that population
The focus of this type of research includes (1) what is being used (an assessment of
specific drugs being used in certain situations) (2) how it is being used (an assessment of the
patterns of use, including how much, where and when, and by whom); and (3) why it is being used (an assessment of the
reasons for drug-taking behaviors and the functions that drugs serve in society).
World Health Organization WHO focuses its pharmacoepidemiological efforts on
ensuring the quality, safety, and efficacy of drugs and their use in specific populations and studies are performed to : (1) Describe current patterns of drug use in specific
patient populations (2) Determine changes in drug use over time (3) Measure the effects of information, education, promotional activities, media accounts, and price on drug use (4) Detect inappropriate drug use and associated problems
Research methods used most often by pharmacoepidemiologists Cross-sectional study: a prevalence survey of
health and illness in the population at one point in time Case-control study, a retrospective analysis comparing subjects with the condition (cases) to those without it (controls) with respect to possible risk or causative factors Cohort study, an incidence study that follows a population free of health problems over time, examining subsequent development of problems and factors associated with them. Clinical trials, an experimental approach that tests the value of a new treatment or intervention
Sources of Data on Drug Use Institutional record systems and
databases drug utilization studies hospital-based medical audits (inpatient) System wide databases institutionally based reviews (outpatient) health insurance groups and third-party
payers pharmaceutical organizations commercial vendors of marketing studies
National databases government-sponsored studies essential drug lists and inventory data
pharmacoepidemiological surveillance
systems Field data records of drug dispensers, sellers, and
distributors drug-taking behaviors of individuals and small groups Experimental data
Problem Solving with Pharmacoepidemiology Medical drug use Beneficial effects of drug therapy Risks (e.g., adverse reactions, side effects) of
drug therapy Inappropriate prescribing behaviours Patient noncompliance Irrational self-medication practices Poor drug use outcomes Cost-effectiveness of drug therapy
Nonmedical drug use Social-recreational drug use and associated
problems Acute incidents of drug toxicities (e.g., overdoses) Chemical dependencies Outbreaks and sources of drug epidemics