Principles of Epidemiology for Clinical and Formulary Management Professionals

management to make decisions that are clinically justified and economically prudent. Epidemiology is concerned primarily with the distribution and determinants of the frequency of disease in populations.1 Thanks in large part to epidemiology, the middle of the 20th century saw many great advances in public health, such as the Framingham Heart Study,2 identifying the association between cigarette smoking and lung cancer,3 and preventing dental caries by adding fluoride to drinking water.4 Since that time, many applications of epidemiology have been identified, including the study of medication use, or pharmacoepidemiology. Pharmacoepidemiology has appropriately been described as the merger of the disciplines of pharmacology and epidemiology.5 Pharmacoepidemiology has made significant contributions to our knowledge of medications, especially with regard to their safety. As interest in risk-management strategy and individualized prescribing escalates, clinicians and formulary professionals will need to be equipped to digest and apply complex study results. Ill-designed studies can lead to biased estimates of effects between medications and outcomes. When these results influence clinical and policy decisions, patients may be placed at undue risk and payers may spend limited resources in vain. Informed practitioners can minimize the damage caused by misleading study results. Issues of confounding and bias (described later) are challenges that researchers face, especially in observational studies. Techniques exist to prevent and adjust for these biases analytically, and an understanding of their characteristics is vital to interpreting and applying study results. In this article, we discuss the principles of pharmacoepidemiology, its benefits, drawbacks, and examples of its applications.