introduction to Pharmacoepidemiology

breif notes on what is pharmacoepidemiology, why do we need pharmacoepidemiology, whats is its aim and its main applications, advantages and disadvantages

1. PHARMACOEPIDEMIOLOGY 10/9/2017 1

2. WHAT IS PHARMACOEPIDEMIOLOY Pharmacoepidemiology is the study of use and effect of drugs in large no of people. PE is the application of principles of epidemiology to drug effects and drug use. The term pharmacoepidemiology contains two components “ pharmaco ” and “epidemiology” Pharmaco means drug & epidemiology means study of distribution and determinants of disease in a population 10/9/2017 2

3. E pidemiology has two major areas- one is the study of infectious disease in large population called epidemics and the second is the study of chronic disease. PE involves gathering & analysis of information in order to identify possible causation & related factors that can be applied in clinical practice to group of people &also individual undergoing treatment. So it examines the relationship b/w drug exposure & health outcome in a defined population. 10/9/2017 3

4. ORIGIN & EVOLUTION Initially there were no regulation to ensure the safety and efficacy of drugs available in the market. In 1906 US govt passed pure food and drug act in response to excessive adulteration & misbranding of food and drugs. In 1937 ,over 100 of people died from renal failure as a result of the elixir sulfanilamide dissolved in diethylene glycol. 10/9/2017 4

5. In 1938 D&C act was passed , bcoz of this manufactures required an approvel from FDA before marketing a drug. In 1950 chloramphenicol induced aplastic anemia discovered In the same year drug induced dyscrasias . In 1961 , the case reports of maternal use of thalidomide with malformation in offspring results in awareness of the potential for drugs to cause ADR. 10/9/2017 5

6. In 1968 UK established a committee on safety of medicine. WHO established a bureau to collect and analyse information from this and similar national drug monitoring organizations. In early 1960, the related field of drug utilization was developed along with the study of ADRs With all these development 1960’s considered to be the beginning of field of pharmaco epidemiology. ISPE was formed to obtain more data on risk & benefits of drugs in population and to discuss, develop & disseminate information about pharmacoepidemiological methods. 10/9/2017 6

7. WHO NEED……. Since PE is considered as a science of understanding of medicine safety issues,all those who use, prescribe, study, monitoror deal with medicine at academic ,research or regulatory level need PE. 10/9/2017 7

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9. NEED OF PE Lack of alternative models to investigate some drug events. Eg.to evaluate the teratogenic effect of a new medicine. CTs are inadequate to answer to questions about drug safety as they lack adequate statistical power. If at all adequate for establishing effectiveness, the sample size are inadequate to detect less common ADR. 10/9/2017 9

10. CTs are conducted on highly selected patients without any co-morbidities and who taking no other medications. CT does not involve elderly paediatric or pregnant patients. CT investigates the single indication Hence CT fail to provide adequate information related to safety and efficacy of a drug under non trial condition. 10/9/2017 10

11. In contrast, PE models provide alternative approaches to evaluate drug effects . 10/9/2017 11

12. AIMS 0F PE The pharmacoepidemiological studies concentrate on the period after the drug enters the market known as post marketing surveillance (PMS) These studies are concerned with two main aspects: 1. the study of adverse effects of drugs 2. the appropriate use of medicines 10/9/2017 12

13. SIGNAL GENERATION The term signal is widely used in electronics for many years . it was coined in ADR reporting and pharmacovigilance in recent times with the evolvement of ADR monitoring system at global level with support of WHO. It is used as an early warning in the case of ADRs. Signal is a reported information on a possible causal relationship between an adverse event and a drug or medicine. Eg ; aspirin 1 st indicated for pain & inflamation later it is used for in cardiac disease bcoz of its blood thinning property Minoxidil - anti hypertensive, hirsutism 10/9/2017 13

14. RISK QUANTIFICATION Risk quantification is the process of evaluating the risk that have been identified & developing the data for other purposes like making decisions on other occations . Various measures of the risk are used in PE to quantify the probability of experiencing an adverse outcome capture the relative increases in risk b/w treated & untreated populations. eg ; cumulative incidence, incidence rate, absolute risk reduction , relative risk, odds ratio, incidence rate ratio 10/9/2017 14

15. HYPOTHESIS TESTING In PE it involves the use of comparison groups of population to find out whether there are differences variables of interest 10/9/2017 15

16. APPLICATION ESTIMATION OF RISKS OF DRUG USE : The risk involved in drug use can be quantified The benefits & risks of use of a drug may be weighed Risk estimation also helps to identify risk situation 10/9/2017 16

17. Ex: Case reports of triazolam induced psychiatric disturbances appeared soon after its introduction to market The drug was withdrawn in some countries The reaction was likely due to dose related, hence the problem was abated by recommending a lower dose 10/9/2017 17

18. USE IN PATIENT COUNSELING: collection & analysis of observational data from other studies may help to address certain issues through counseling the patients Ex: A pregnant patient may wish to terminate pregnancy if there is a substantial risk for producing a seriously malformed child, but would also wish to proceed with the pregnancy if the risk is low. 10/9/2017 18

19. FORMULATION OF PUBLIC HEALTH POLICY DECISIONS: Qualitative as well as quantitative information from PEY studies helps to address many issues Ex: If an inappropriate prescribing is observed among prescribers, regulatory agencies may require educational intervention or may impose restrictions on specific drugs or on practitioners PEY studies also helps the policy makers to assess whether a drug should be withdrawn from the market or allowed to remain 10/9/2017 19

20. FORMULATION OF THERAPEUTIC GUIDELINES & DISCOVERY OF NEW INDICATIONS: PEY studies helps to examine the effectiveness of drugs in elderly & pediatric patients Also in patients with co-morbidities and/or using other medications PEY studies help to discover the new indications of a drug 10/9/2017 20

21. FACILITATION OF PHARMACOECONOMICS EVALUATIONS Data from PEY studies can be used to measure the effects of drugs on overall health care costs & resource consumption Ex: Hospitalization due to serious adverse effects of a drug leads to more expenses as well as resource consumption, which could be avoidable. 10/9/2017 21

22. OTHER APPICATIONS 1. Age based medicine use and it’s analysis. 2. Generation of data bases for other studies 3. Pharmacovigilance 4.drug usage analysis 5.empowering pharmacogenomic studies 6.evaluation of hospital committees 10/9/2017 22

23. ADVANTAGES OF PE Can be useful in many cases where other models cannot Allow quantification of drug effects in special population/patients with co morbid conditions & patients who are on polypharmacy Allows quantification of drug effects in a more realistic environment 10/9/2017 23

24. Serve as alerting mechanism for clinicians, manufacturers and regulatory authorities Also serve as signal generators which further directs towards research and indicate new areas to explore Allows comparison of drug use patterns between areas Quantification of DRPs Allows rational use of drugs 10/9/2017 24

25. DISADVANTAGES OF PE These are non-experimental studies Some times Causation may be difficult Confounding factors, biases (like selection, informational) may threaten the validity 10/9/2017 25

26. REFERENCE Text book of Pharmacoepidemiology by BRIAN L. STORM,Third edition. WWW.PharmaDost.info Pharmacoepidemiology & pharmacoeconomics concepts and practice by K.G Ravikumar . 10/9/2017 26