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 rooms for an ADE, and approximately 100,000 were admitted or transferred to another facility (Budnitz, 2005). Early data indicate that unintentional overdoses were the most common cause of ADEs (39 percent), and that two drugs (i.e., warfarin and insulin) were associated with 16 percent of all ADEs and 33 percent of ADEs in patients over age 50 (Budnitz et al., 2005).
NEISS-CADES has several important limitations. First, the system is limited to ADEs occurring outside the hospital and to those that result in emergency room visits. Second, the system may fail to capture some serious outpatient ADEs (those treated in a care setting other than an emergency department) and may include nonserious events (as patients may use emergency departments for primary health care) (Walls et al., 2002). Third, the system is designed for national surveillance and not for quality improvement by individual hospitals. Nonetheless, given the importance of monitoring the national health burden of ADEs as one aspect of medication safety and quality improvement, the continued operation and enhancement of NEISS-CADES could play an important role in monitoring the nation’s progress toward reducing medication-related harm in the outpatient setting. The system’s usefulness would be enhanced by identifying appropriate measures of drug exposure, ensuring continued data quality, and developing mechanisms for timely data dissemination.