Emergency department visits by adults for psychiatric medication adverse events.

IMPORTANCE In 2011, an estimated 26.8 million US adults used prescription medications for mental illness. OBJECTIVE To estimate the numbers and rates of adverse drug event (ADE) emergency department (ED) visits involving psychiatric medications among US adults between January 1, 2009, and December 31, 2011. DESIGN AND SETTING Descriptive analyses of active, nationally representative surveillance of ADE ED visits using the National Electronic Injury Surveillance System-Cooperative Adverse Drug Event Surveillance system and of drug prescribing during outpatient visits using the National Ambulatory Medical Care Survey and the National Hospital Ambulatory Medical Care Survey. PARTICIPANTS Medical records from national probability samples of ED and outpatient visits by adults 19 years or older were reviewed and analyzed. EXPOSURES Antidepressants, antipsychotics, lithium salts, sedatives and anxiolytics, and stimulants. MAIN OUTCOMES AND MEASURES National estimates of ADE ED visits resulting from therapeutic psychiatric medication use and of psychiatric medication ADE ED visits per 10,000 outpatient visits at which psychiatric medications were prescribed. RESULTS From 2009 through 2011, there were an estimated 89,094 (95% CI, 68,641-109,548) psychiatric medication ADE ED visits annually, with 19.3% (95% CI, 16.3%-22.2%) resulting in hospitalization and 49.4% (95% CI, 46.5%-52.4%) involving patients aged 19 to 44 years. Sedatives and anxiolytics, antidepressants, antipsychotics, lithium salts, and stimulants were implicated in an estimated 30,707 (95% CI, 23,406-38,008), 25,377 (95% CI, 19,051-31,704), 21,578 (95% CI, 16,599-26,557), 3620 (95% CI, 2311-4928), and 2779 (95% CI, 1764-3794) respective ADE ED visits annually. Antipsychotics and lithium salts were implicated in 11.7 (95% CI, 10.1-13.2) and 16.4 (95% CI, 13.0-19.9) ADE ED visits per 10,000 outpatient prescription visits, respectively, compared with 3.6 (95% CI, 3.2-4.1) for sedatives and anxiolytics, 2.9 (95% CI, 2.3-3.5) for stimulants, and 2.4 (95% CI, 2.1-2.7) for antidepressants. The commonly used sedative zolpidem tartrate was implicated in 11.5% (95% CI, 9.5%-13.4%) of all adult psychiatric medication ADE ED visits and in 21.0% (95% CI, 16.3%-25.7%) of visits involving adults 65 years or older, in both cases significantly more than any other psychiatric medication. CONCLUSIONS AND RELEVANCE Psychiatric medications are implicated in many ADEs treated in US EDs. Efforts to reduce ADEs should include adults of all ages but might prioritize medications causing high numbers and rates of ED visits.