Stroke prophylaxis in institutionalized elderly patients with atrial fibrillation

OBJECTIVES: To identify patterns and predictors of antithrombotic use and to evaluate the appropriateness of antithrombotic therapy for stroke prophylaxis in institutionalized elderly patients with atrial fibrillation. DESIGN: Retrospective study. SETTING: Seventeen long-term care institutions in Edmonton, Alberta. SUBJECTS: Two hundred sixty-five long-term care residents, aged 65 and older, with atrial fibrillation. MEASUREMENTS: The proportion of patients who were prescribed warfarin, acetylsalicylic acid (ASA), both, or neither was determined. Odds ratios were calculated to identify risk factors for stroke and bleeding that are predictive of the receipt of anticoagulant therapy. Appropriateness of therapy was evaluated based on whether patients were prescribed antithrombotic therapy in accordance with their risk factors for stroke and bleeding. RESULTS: Warfarin was prescribed for 49% of patients, ASA for 22%, both for 8%, and neither for 20%. Nearly all patients (97%) were considered to be at high risk for stroke, with age being the predominant risk factor (88%>75), whereas about half were considered to be at low risk for bleeding. Multivariate analyses did not find any associations between individual risk factors for bleeding and anticoagulant treatment, with the exception of recent surgery (odds ratio=0.59, 95% confidence interval=0.37-0.94). Overall, 54.8% of patients received appropriate antithrombotic therapy. Of patients who were optimal candidates for anticoagulation, 60% received appropriate therapy (warfarin with or without ASA). CONCLUSION: Although warfarin was the most appropriate treatment in nearly all of this population at high risk for stroke, it was prescribed in fewer than two-thirds of patients. Antithrombotic therapy was not always prescribed in accordance with patients' risk factors for stroke and bleeding. There is a need for systematic identification of appropriate candidates for anticoagulation in the long-term care setting.