Postmarketing surveillance versus clinical trials: which benefits the patient?

Both randomized controlled clinical trials and observational postmarketing surveillance studies have a place in providing information to physicians and patients on effectiveness and safety of new medicines. Prelicensing is the realm of the basic scientist producing a medicine which is available for investigation by clinical trial. In this context, manufacturers attempt to define the efficacy for desired indications and to establish an appropriate dosage for the drug. To do so, they usually confine attention to idealized standard patients, excluding all complex problems, such as pregnancy, renal or other organ failure, comorbidity, the elderly, the child, and so forth. Postmarketing surveillance covers the range of observational studies undertaken after marketing including cohort studies, case-control studies, and spontaneous reports of suspected adverse drug reactions. These observational studies are less rigorous than clinical trials, but have the potential to provide information from a representative sample of 'real-life' patients. Neither postmarketing surveillance studies nor clinical trials are capable of answering questions fully. In future, record linkage techniques may play a greater role by providing information on data linking drug exposures and outcomes in general practice.