Oral Anticoagulants vs Aspirin in Nonvalvular Atrial Fibrillation

To compare the risk of vascular and bleeding events in patients with nonvalvular AF treated with vitamin K -inhibiting oral anticoagulants or acetylsalicylic acid (aspirin).

Pooled analysis of patient-level data from 6 published, randomized clinical trials. PATIENTS: A total of 4052 patients with AF randomly assigned to receive therapeutic doses of oral anticoagulant or aspirin with or without low-dose oral anticoagulants. MAIN OUTCOME MEASURES: Ischemic and hemorrhagic stroke, other cardiovascular events, all-cause death, and major bleeding events. Person-year incidence rates were calculated to provide crude comparisons. Relative efficacy was assessed using proportional hazards modeling stratified by study. The variation of the oral anticoagulant's relative effect by pertinent patient factors was explored with interaction terms. All analyses were conducted using the intention-to-treat principle.