Epidemiology of medication-related adverse events in nursing homes

Background: Nursing home residents are prescribed more medications than patients in any other clinical setting. Although pharmacotherapy for older nursing home residents is usually safe and effective, it can lead to medication-related adverse events such as adverse drug reactions (ADRs), adverse drug withdrawal events (ADWEs), and therapeutic failures (TFs). Objective: This article reviews the descriptive (incidence) and analytic (risk factor) epidemiology of medication-related adverse events occurring in nursing home residents as reported in the literature during the last 2 decades. Methods: A search of MEDLINE and International Pharmaceutical Abstracts was conducted for articles published in English between January 1986 and July 2006 using the following terms: adverse drug events, adverse drug reactions, adverse drug withdrawal events, aged, drug therapy, drug-related problems, medication-related problems, nursing homes, therapeutic failures, and treatment failures. The reference lists of identified articles, recent review articles, book chapters, and the authors' reference library were also searched manually. Results: Seven studies met the inclusion and exclusion criteria and were included in this review. Five studies described ADRs, 1 described ADWEs, and 1 described TFs. The studies of ADRs used different methods of detecting ADRs, resulting in incidence rates ranging from 1.19 to 7.26 per 100 resident-months. The single study of ADWEs reported an incidence of 2.60 per 100 resident-months. An incidence rate for the single study describing TFs could not be calculated. Conclusions: Medication-related adverse events are common in the nursing home setting. Additional studies are needed to enhance the detection and prevention of medication-related adverse events and to reduce their impact on residents' outcomes and health care costs.