Pharmacoepidemiology Definition and scope Kanav Khera Lecturer Dept of Pharmacy Practice
Definition and scope:
Pharmacoepidemiology: Study of the use Pharmacoepidemiology: 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), Σ Analytic epidemiology , in which the objective is to study the associations (causal or otherwise) Σ
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
Adverse reactions
Type A reactions: reactions tend to be common, doserelated, 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.
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
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
Grey baby syndrome with chloramphenicol \
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
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
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
Reasons to perform pharmacoepidemiology studies
pp cat on o 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
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.
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
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
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
