Abstract 19280: Real World Comparisons of Major Bleeding Risk Stratified by CHA2DS2-VASc Scores Among Non-Valvular Atrial Fibrillation Patients Initiating Apixaban or Warfarin

Objective: To compare the risk of major bleeding overall and stratified by CHA2DS2-VASc score, among non-valvular atrial fibrillation (NVAF) patients initiating apixaban and warfarin. Methods: This is a retrospective cohort study using MarketScan® Commercial and Medicare supplemental data. NVAF patients newly prescribed warfarin or apixaban with ≥1 year of baseline period were identified (study period: 01JAN2012-30JUN2015). Patients were stratified by CHA2DS2-VASc score, an indicator of stroke risk, where patients with a score <2 and ≥2 were considered low and high risk for stroke, respectively. Major bleeding was defined as bleeding requiring hospitalization (based on the first listed ICD-9-CM diagnosis code). Cox proportional hazards models were used to estimate the hazard ratio (HR) of major bleeding risk, adjusted for age, sex, geographic region, and baseline comorbidities. Results: The study included 36,427 patients: 13,456 apixaban (37%) and 22,971 warfarin (63%); among whom 10,671 (79%) apixaban an...