Summary: About 2.7 billion prescriptions were filled in the United States in 1998. Although prescription drugs have great clinical benefits, serious adverse drug events can lead to hospitalization, disability, and even death. Adverse drug events are caused by harmful drug reactions or by medication errors committed by health care professionals and patients. Two factors that can increase the risk of a patients' suffering from an adverse drug event are illness severity and intensity of treatment, including taking several drugs simultaneously. Although it is clear that a wide range of commonly used drugs cause adverse drug events with potentially serious consequences for patients, relatively little is known about their frequency. Data routinely collected on adverse drug events during clinical trials or after drugs are marketed are intended to identify the adverse drug events that are associated with particular drugs and do not focus on their frequency. Information on the overall incidence of adverse drug events from all drugs has been limited to a few research studies that typically examined the experience of patients in one of two specific institutions--generally hospitals or sometimes nursing homes--leaving the overall incidence of adverse drug events in outpatient care largely unexplored. Greater understanding of certain factors that affect the likelihood of adverse drug events has led researchers and patient safety advocates to suggest a range of measures to decrease their number and severity. These proposals range from better communication between doctors and patients about the risks and benefits of medications to accelerating research on the safety of marketed drugs. Suggestions for reducing medication errors include developing computerized prescribing and dispensing systems to detect possible errors, increasing the role of pharmacists as advisers to physicians and as monitors of drug therapy, and improving health care providers' pharmaceutical education. This testimony summarizes the January 2000 report, GAO/HEHS-00-21.
