Cost Effectiveness of Warfarin Versus Aspirin in Patients Older Than 75 Years With Atrial Fibrillation

BACKGROUND AND PURPOSE: Oral anticoagulants are effective at reducing stroke compared with aspirin in atrial fibrillation patients older than 75 years. Although the benefits of reduced stroke risk outweigh the risks of bleeding, the cost effectiveness of warfarin in this patient population has not yet been established. METHODS: An economic evaluation was conducted alongside a randomized, controlled trial; 973 patients ≥75 years of age with atrial fibrillation were recruited from primary care and randomly assigned to either take warfarin or aspirin. Follow-up was for a mean of 2.7 years. Costs of thrombotic and hemorrhagic events, anticoagulation clinic visits, and primary care utilization were determined. Clinical benefits were expressed in terms of a primary event avoided: fatal/nonfatal disabling stroke, intracranial hemorrhage, or systemic embolism. A cost-utility analysis was performed using quality-adjusted life years as the benefit measure. RESULTS: Total costs over 4 years were lower in the warfarin group (difference, -£165; 95% CI, -£452-£89), primarily driven by the difference in primary event costs. The primary event rate over 4 years was lower in the warfarin group (0.049 versus 0.099), and the quality-adjusted life years score was higher (difference, 0.02; 95% CI, -0.07-0.11). With lower costs and a higher quality-adjusted life years score, warfarin is the dominant treatment, but the differences in both costs and effects are small. CONCLUSIONS: Warfarin is cost-effective compared with aspirin in atrial fibrillation patients age ≥75 years. These data support the anticoagulant therapy option in this high-risk patient population. However, the small differences in costs and effects indicate the importance of exploring patient preferences.