Risk factors associated with adverse drug events among older adults in emergency department.

BACKGROUND Little is known about the emergency department (ED) visits from drug-related injury among older adults in Taiwan. This study seeks to identify risk factors associated with adverse drug events (ADEs) leading to ED visits. METHODS We prospectively conducted a case-control study of patients 65years and older presenting to the ED. ED visits between March 1, 2009 and Feb 28, 2010 identified by investigators for suspected ADEs were further assessed by using the Naranjo Adverse Drug Reaction probability scale. For each patient with an ADE, a control was selected and time-matched from the ED population of the study hospital. The association between the risk of adverse drug events and triage, age, gender, serum alanine transaminase (ALT), serum creatinine, number of medications, and Charlson Comorbidity Index scores were analyzed using logistic regression. RESULTS Of 20,628 visits, 295 ADEs were physician-documented in older adults. Independent risk factors for ADEs included number of medications (adjusted odds ratio [OR]=4.1; 95% confidence interval [CI] 2.4-6.9 for 3-7 drugs; adjusted OR=6.4; 95% CI 3.7-11.0 for 8 or more drugs) and increased concentration of serum creatinine (adjusted OR=1.5; 95% CI 1.1-2.2). Diuretics, analgesics, cardiovascular agents, anti-diabetic agents and anticoagulants were the medications most commonly associated with an ADE leading to ED visits. CONCLUSIONS This study suggests that prevention efforts should be focused on older patients with renal insufficiency and polypharmacy who are using high risk medications such as anticoagulants, diuretics, cardiovascular agents, analgesics, and anti-diabetic agents.