Pharmacoepidemiology Definition and scope Definition and scope Pharmacoepidemiology

Pharmacoepidemiology Definition and scope

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 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. �Σ Descriptive epidemiology, in which the objective is to describe a population (e. g. drug utilization studies), �Σ 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 defined

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 20 th 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 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 1 st 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 whethere 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 and sales data

�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