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 and 19,701 (85%) warfarin patients were high risk for stroke. In the overall and high risk populations, patients initiating warfarin were older (overall: 72 vs. 69 years; high risk: 75 vs. 73 years) and had higher CHA2DS2-VASc scores (overall: 3.6 vs. 3.2; high risk: 4.1 vs. 3.8) than patients initiating apixaban. In the low risk group, patients initiating warfarin were older (58 vs. 57 years) and had similar CHA2DS2-VASc scores (0.7 vs. 0.7) compared to patients initiating apixaban. After adjusting for baseline characteristics, patients initiating apixaban had a significantly lower risk of major bleeding compared to warfarin initiators in the overall (HR: 0.61, 95% CI: 0.51-0.72, p < 0.0001), low risk (HR: 0.37, 95% CI: 0.18-0.77, p=0.0073) and high risk populations (HR: 0.63, 95% CI: 0.53-0.75, p < 0.0001).
Conclusions: In a real-world setting, apixaban initiation was associated with a significantly lower risk of major bleeding compared to warfarin initiation among NVAF patients with high and low stroke risk.
Author Disclosures: G.Y. Lip: Consultant/Advisory Board; Significant; Dr Lip has served as a consultant for Bayer, Astellas, Merck, AstraZeneca, Sano?, BMS/Pfizer, Biotronik, Portola and Boehringer Ingelheim. A. Keshishian: Employment; Significant; A Keshishian is an employee of STATinMED Research, which is a paid consultant to Bristol-Myers Squibb Company and Pfizer Inc., the study sponsors. S. Kamble: Employment; Significant; S Kamble is an employee of Bristol-Myers Squibb Company, the study sponsor. X. Pan: Employment; Significant; X Pan is an employee of Bristol-Myers Squibb Company. J. Mardekian: Employment; Significant; J Mardekian is an employee of Pfizer Inc, the study sponsor. R. Horblyuk: Employment; Significant; R. Horblyuk is an employee of Pfizer Inc, the study sponsor. M. Hamilton: Employment; Significant; M Hamilton is an employee of Bristol-Myers Squibb Company, the study sponsor..
- © 2016 by American Heart Association, Inc.