Pharmacoepidemiology.

At the time of their marketing authorization, the effects of drugs and especially their efficacy have been mostly studied in randomized controlled clinical trials (RCT), comparing them to placebo or to existing drugs. However, RCT are by nature limited in their extent, and the often stringent inclusion and exclusion criteria destined to provide for homogeneous study populations reduce the generalizability of RCT results.The post-authorization evaluation of drugs (pharmacoepidemiology or real-world evidence (RWE)) covers the description of drug utilization and population risks or benefits of these drugs after they have been marketed and provided to their target populations. Though field studies have existed for a long time, modern pharmacoepidemiology has been made possible essentially by the emergence of large population databases compiled from claims data or electronic health records. The methods can be exposure or disease-based cohorts or event-driven case-based studies, tailored to the specific questions to be answered. They rely on scrupulous analysis and execution of impeccable methodology, to ensure the most reliable results possible.Pharmacoepidemiology requires knowledge of the pharmacology of drugs, of the clinical aspects of diseases and disease management, and of the epidemiological methods that can apply.