Intended for healthcare professionals

Education And Debate

Detection, verification, and quantification of adverse drug reactions

BMJ 2004; 329 doi: (Published 01 July 2004) Cite this as: BMJ 2004;329:44
  1. Bruno HCh Stricker, professor of pharmacoepidemiology1 (,
  2. Bruce M Psaty, professor of medicine, epidemiology, and health services2
  1. 1 Pharmacoepidemiology Unit, Department of Epidemiology and Biostatistics, Erasmus Medical Center, PO Box 1738, 3000 DR Rotterdam
  2. 2 Cardiovascular Health Research Unit, Departments of Medicine and Epidemiology, University of Washington, Seattle, USA
  1. Correspondence to: B HCh Stricker
  • Accepted 30 May 2004

The current system of verifying and quantifying adverse reactions to new drugs is too disparate. Epidemiological studies for testing a hypothesis have a part to play in protecting the public from the harmful effects of new drugs


Although some will question the use of the term experiment on formal grounds, most experts will likely agree that the widespread marketing of a new drug is in fact a large experiment on a population. This is especially the case when it concerns a novel molecular entity with potentially a new set of clinical experiences. As the marketing of new drugs includes the discovery of adverse effects, the public's health would be best protected by a complementary set of techniques for the detection, verification, and quantification of safety issues. Yet the current approach to this is scattered and disappointing. We discuss why healthcare professionals are not aware of all safety problems of a drug at its introduction and why pharmacoepidemiology should complement the indispensable observational method of case reporting.

Sources and selection criteria

Our review is based on a search of PubMed using the terms adverse effect, adverse reaction, ADR, adverse event, adverse reaction monitoring, pharmacovigilance, cohort study, and case-control study. This yielded several thousand papers from which we excluded individual case reports and case series. From a list of cohort and case-control studies, we picked some recent examples of pharmacoepidemiological studies of adverse events with databases. We used the references from 50 of the most recent reviews, to gather the most important papers on this subject.

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Limitations of clinical trials

Before drugs are marketed, they are extensively tested in animals and in clinical trials in humans. These tests tell much about the drug's efficacy but for several reasons relatively little about safety (box).

Good economical reasons preclude an endless quest for research before drugs are registered. Such …

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