Aspirin Instead of Oral Anticoagulant Prescription in Atrial Fibrillation Patients at Risk for Stroke

Background Oral anticoagulation (OAC), rather than aspirin, is recommended in patients with atrial fibrillation (AF) at moderate to high risk of stroke. Objectives This study sought to examine patient and practice-level factors associated with prescription of aspirin alone compared with OAC in AF patients at intermediate to high stroke risk in real-world cardiology practices. Methods The authors identified 2 cohorts of outpatients with AF and intermediate to high thromboembolic risk (CHADS₂ score ≥2 and CHA₂DS₂-VASc ≥2) enrolled in the American College of Cardiology PINNACLE (Practice Innovation and Clinical Excellence) registry between 2008 and 2012. Using hierarchical modified Poisson regression models adjusted for patient and practice characteristics, the authors examined the prevalence and predictors of aspirin alone versus OAC prescription in AF patients at risk for stroke. Results Of 210,380 identified patients with CHADS₂ score ≥2 on antithrombotic therapy, 80,371 (38.2%) were treated with aspirin alone, and 130,009 (61.8%) were treated with warfarin or non-vitamin K antagonist OACs. In the cohort of 294,642 patients with CHA₂DS₂-VASc ≥2, 118,398 (40.2%) were treated with aspirin alone, and 176,244 (59.8%) were treated with warfarin or non-vitamin K antagonist OACs. After multivariable adjustment, hypertension, dyslipidemia, coronary artery disease, prior myocardial infarction, unstable and stable angina, recent coronary artery bypass graft, and peripheral arterial disease were associated with prescription of aspirin only, whereas male sex, higher body mass index, prior stroke/transient ischemic attack, prior systemic embolism, and congestive heart failure were associated with more frequent prescription of OAC. Conclusions In a large, real-world cardiac outpatient population of AF patients with a moderate to high risk of stroke, more than 1 in 3 were treated with aspirin alone without OAC. Specific patient characteristics predicted prescription of aspirin therapy over OAC.