Chapter 1. Introduction to Pharmacoepidemiology

At the end of the chapter, the reader will be able to:

1. Define pharmacoepidemiology as it relates to pharmacy and public health

2. Explain the U.S. drug development and approval process, including its strengths and limitations

3. Identify two limitations of clinical trials and two limitations of spontaneous adverse event reporting in understanding drug use in a population

4. Describe the need for pharmacoepidemiology in the U.S. health care system

5. Explain how health care databases have facilitated the growth of the pharmacoepidemiology discipline

6. Provide three practice-related questions of interest to pharmacoepidemiologists

7. List three ways in which pharmacists or public health practitioners can contribute to pharmacoepidemiology

Pharmacoepidemiology is the study of the use and effects of drugs in large numbers of people.1(p3) It is a growing discipline that applies epidemiological techniques to study drug use in a large population.2,3 Just as the term implies, pharmacoepidemiology combines clinical pharmacology with epidemiology. Pharmacology is the study of the effects of medications in humans.1(p4) It pertains to using pharmacokinetics and pharmacodynamics of a patient to predict the drug effect on a patient. Epidemiology is the study of the factors that determine the occurrence and distribution of diseases in populations.4(p3) Epidemiologists study how much disease is in a given area, who gets it, and what specific factors put individuals at risk. Epidemiology can often be divided into infectious and chronic disease epidemiology. Chronic disease epidemiology is more dependent on complex sampling and statistical methods; which are often used in pharmacoepidemiology studies to evaluate drug exposure over time.1(p5) By combining the interest of pharmacology and epidemiology, a pharmacoepidemiologist applies epidemiology principles to study the effects of medications in human populations.

Pharmacoepidemiology studies quantify drug use patterns and adverse drug effects.5 For example, they are interested in understanding the patterns of drug prescribing, the appropriateness of use, medication adherence and persistence patterns, and the identification of predictors for medication use. Pharmacoepidemiologists also conduct safety studies of drug use in large populations. They are interested in common, predictable adverse drug reactions as well as the uncommon and unpredictable ones. It is important to note a few terms that are often used when discussing drug safety (see Chapter 9 for further discussion). An adverse event is any untoward medical occurrence that occurs while a patient is taking a drug but which does not necessarily have a causal relationship with the drug product.6,7 An adverse drug reaction or adverse drug effect refers to an adverse outcome that is harmful or unpleasant that occurs while a patient is taking a drug product and has a causal link with the drug.6,7 Adverse drug reactions may be dose dependent (i.e., there is a relationship between the drug dose and the outcome observed) and predictable or more idiosyncratic and unpredictable. A side effect is usually a dose-dependent effect of a drug that is predictable and may ...