Abstract 19679: Is Major Bleeding Risk for Oral Anticoagulants Similar Among Newly Initiated Non Valvular Atrial Fibrillation Patients?

Abstract

Aim: The purpose of this study was to compare the risk of first major inpatient/outpatient bleeding event among non valvular atrial fibrillation (NVAF) patients newly initiated with warfarin versus non-vitamin K antagonist oral anticoagulants (NOACs) including apixaban, dabigatran, or rivaroxaban. Methods: Retrospective cohort study was conducted using MarketScan® database from 01/2012 to 12/2013. NVAF patients 18+ years with ≥1 year baseline period were included if they were newly prescribed an oral anticoagulant from 01/01/ 2013 to 12/31/2013. Major bleeding on anticoagulant was defined as inpatients and/or outpatient bleeding on the index drug during the supply duration or within 30 days after the last supply day of the last prescription. A Cox proportional hazards model was used to estimate the hazard ratios (HR) of major bleeding adjusted for age, sex, baseline comorbidities, and comedications. Results: Among 29,338 NVAF patients newly initiated on an oral anticoagulant, 2,402 (8.19%) were on apixaban, 4,173 (14.22%) on dabigatran, 10,050 (34.26%) on rivaroxaban and 12,713 (43.33%) on warfarin. Patients initiating warfarin (72.5±11.9 yrs) and apixaban (69.3±12.3 yrs) were older as compared to rivaroxaban (67.3±12.2 yrs) and dabigatran (66.8±12.1 yrs). Patients initiating warfarin were higher risk as compared to those initiating NOACs in terms of CHA 2 DS 2- VASc score (3.22±1.65) and higher Charlson comorbidity index (CCI) score of 2.37±2.33 (p <0.0001 across all treatments). After adjusting for baseline characteristics, as compared to patients newly initiated on warfarin, patients newly initiated on apixaban or dabigatran had significantly lower risk of major bleeding (Table). Conclusion: Among newly anticoagulated NVAF patients in the real world setting, initiation with apixaban or dabigatran was associated with significantly lower risk of major bleeding compared to initiation on warfarin.