Abstract W P330: Antithrombotic Treatment Patterns Among Patients with Non-Valvular Atrial Fibrillation in a Managed Care Setting

Abstract

Background: Antithrombotic therapy (warfarin or aspirin (ASA)) has been recommended to reduce the risk of stroke in patients with NVAF. The purpose of this study was to describe antithrombotic treatment patterns and baseline differences for managed care patients newly diagnosed with NVAF. Methods: Patients age ≥18 years and newly diagnosed with NVAF (index date) were identified between 01/01/2006_12/31/2011 within Kaiser Permanente Southern California databases and followed until 12/31/2012. Prescriptions, anticoagulation clinic information, and international normalized ratio (INR) monitoring were used to create 4 treatment groups: 1) continuous warfarin, 2) discontinuous warfarin (≥1 treatment gap >80 days), 3) ASA only, and 4) no antithrombotic therapy. Descriptive statistics were used to compare groups. Results: A total of 28,776 patients were identified with median follow up of 2.5 years. Among the 81% of patients (23,297) with ≥1 CHADS 2 risk factor for stroke at baseline: 27.4% were continuously treated with warfarin, 22.0% discontinued warfarin, 28.5% were on ASA only, and 22.1% received no therapy. Using the Rosendaal method, median time in INR range 2-3 for all warfarin-treated patients was 59%, which does not include patient-specific ranges. ASA users were older (mean±SD age: 77.6±10.8) compared to continuous warfarin users (73.7±9.6, p<0.001). Continuous warfarin users had higher rates of comorbidities: hypertension, diabetes, and stroke compared to the ASA group (stroke: 4.4% vs. 2.2% respectively, p<0.001), whereas the ASA and no therapy groups had higher rates of congestive heart failure, myocardial infarction, and bleeding (bleeding: 9.0% ASA, 9.8% no therapy, 6.5% continuous warfarin, p<0.001). CHADS 2 scores were slightly higher for ASA users compared to continuous warfarin or no therapy (2.04±0.92 ASA, 2.01±0.90 continuous warfarin, 1.93±0.93 no therapy, p<0.001). Conclusion: Patients with newly diagnosed NVAF have varied treatment patterns and baseline comorbidities including rates of stroke and bleed. Future studies should evaluate risks and benefits associated with these real world treatment patterns.