Centers for Disease Control and Prevention’s Active Surveillance
Systems for Clinical Care The CDC’s adverse event surveillance
systems include the National Healthcare Safety Network (the
successor to the National Nosocomial Infections Surveillance
System, the Dialysis Surveillance Network, and the National
Surveillance System for Health Care Workers) (Tokars et al.,
2004) and the National Electronic Injury Surveillance System-
Cooperative Adverse Drug Event Surveillance project (NEISS-
CADES). Through NEISS-CADES, the CDC conducts nationally
representative surveillance for adverse drug events (ADEs)
treated in hospital emergency departments. The program is aimed
at controlling or preventing injury by identifying and
describing the public health burden of outpatient ADEs,
generating hypotheses about risk factors for these events, and
helping to design interventions for reducing medication errors
in the outpatient setting. Estimates for 2004 indicate that
approximately 700,000 patients were treated in emergency