Risk factors for adverse drug events among nursing home residents

Background: In a prospective study of nursing home residents, we found adve rse drug events (ADEs) to be common, serious, and often preventable. To dir ect prevention efforts at high-risk residents, information is needed on res ident-level risk factors. Methods: Case-control study nested within a prospective study of ADEs among residents in 18 nursing homes. For each ADE, we randomly selected a contro l from the same home. Data were abstracted from medical records on function al status, medical conditions, and medication use. Results: Adverse drug events were identified in 410 nursing home residents. Independent risk factors included being a new resident (odds ratio [OR], 2 .8; 95% confidence interval [CI], 1.5-5.2) and taking anti-infective medica tions (OR, 4.0; CI, 2.5-6.2), antipsychotics (OR, 3.2; CI, 2.1-4.9), or ant idepressants (OR, 1.5; CI, 1.1-2.3). The number of regularly scheduled medi cations was associated with increased risk of ADEs; the OR associated with taking 5 to 6 medications was 2.0 (CI, 1.2-3.2); 7 to 8 medications, 2.8 (C I, 1.7-4.7); and 9 or more, 3.3 (CI, 1.9-5.6). Taking supplements or nutrie nts was associated with lower risk (OR, 0.42; CI, 0.27-0.63). Preventable A DEs occurred in 226 residents. Independent risk factors included taking opi oid medications (OR, 6.6; CI, 2.3-19.3), antipsychotics (OR, 4.0; CI, 2.2-7 .3), antiinfectives (OR, 3.0; CT, 1.6-5.8), antiepileptics (OR, 2.2; CI, 1. 1-4.5), or antidepressants (OR, 2.0; CI, 1.1-3.5). Scores of 5 or higher on the Charlson Comorbidity Index were associated with increased risk of ADEs (OR, 2.6; CI, 1.1-6.0). The number of regularly scheduled medications was also a risk factor: the OR for 7 to 8 medications was 3.2 (CI, 1.4-6.9) and for 9 or more, 2.9 (CI, 1.3-6.8). Residents taking nutrients or supplement s were at lower risk (OR, 0.27; CI, 0.14-0.50). Conclusions: It is possible to identify nursing home residents at high risk of having an ADE. Particular attention should be directed at new residents , those with multiple medical conditions, those taking multiple medications , and those taking psychoactive medications, opioids, or anti-infective dru gs.