Signal generation and clarification: use of case-control data

Case-control surveillance systems are useful for 'signal' generation, i.e., signaling potential previously unidentified adverse effects of drugs. Two systems currently in operation, the Slone Epidemiology Unit's Case-Control Surveillance and the Birth Defects Study, have monitored drug effects since 1976. With extensive information on the diagnoses and covariates, the syst ems have the capacity to carry out in-depth analyses in which the outcome m easure is more specifically defined and in which confounding is controlled, thus reducing the possibility of false alarms. Copyright (C) 2001 John Wil ey & Sons, Ltd.