The data on adverse drug reactions (ADRs) are incomplete, unrepresentative, uncontrolled, and lacking in operational criteria for identifying ADRs. No quantitative conclusions can be drawn from the reported data in regard to morbidity, mortality, or the underlying causes of ADRs, and attempts to extrapolate the available data to the general population would be invalid and perhaps misleading.
To evaluate the impact as well as the causes of ADRs, representative populations, including general hospital and ambulatory patients of all medical specialties, must be studied, and operationally defined criteria must be used to establish the presence of an ADR in a prospective study that incorporates appropriate control populations. Similar studies on the benefits of drug use are needed to provide perspective on the risk-benefit aspects of drug therapy. Until such studies are performed, estimates of the nature and scope of the ADR problem can be only guesses.
(JAMA 234:1236-1241, 1975)