BLEEDING DURING ANTITHROMBOTIC THERAPY IN PATIENTS WITH ATRIAL-FIBRILLATION

Background: The Stroke Prevention in Atrial Fibrillation II study comp ared warfarin vs aspirin for stroke prevention in atrial fibrillation. Bleeding complications importantly detracted from warfarin's net effe ctiveness, particularly among older patients. Objectives: To analyze b leeding complications according to assigned therapy. To identify risk factors for bleeding during anticoagulation. Methods: Eleven hundred p atients (mean age, 70 years) were randomized to 325 mg of aspirin dail y (enteric coated) vs warfarin (target prothrombin time ratio, 1.3 to 1.8; approximate international normalized ratio, 2.0 to 4.5). Major he morrhages were defined prospectively. Results: The rate of major bleed ing while receiving warfarin was 2.3% per year (95% confidence interva l [CI], 1.7 to 3.2) vs 1.1% per year (95% CI, 0.7 to 1.8) while receiv ing aspirin (relative risk, 2.1; 95% CI, 1.1 to 3.1; P=.02). Intracran ial hemorrhage occurred at 0.9% per year (95% CI, 0.5 to 1.5) with war farin and 0.3% per year (95% CI, 0.1 to 0.8) with aspirin (relative ri sk, 2.4; P=.08). Age (P=.006), increasing number of prescribed medicat ions (P=.007), and intensity of anticoagulation (P=.02) were independe nt risks for bleeding at any site during anticoagulation. The rate of major hemorrhage was 1.7% per year in patients aged 75 years or younge r who received anticoagulation vs 4.2% per year in older patients (rel ative risk, 2.6, P=.009); rates by age for intracranial bleeding were 0.6% per year and 1.8% per year, respectively (P=.05). Conclusion: Adv ancing age and more intense anticoagulation increase the risk of major hemorrhage in patients given warfarin for stroke prevention.