P4566Risk of major bleeding among non-valvular atrial fibrillation patients prescribed apixaban, dabigatran, rivaroxaban, or warfarin in the US Medicare population

Abstract

Background: Clinical trials have shown direct oral anticoagulants (DOACs) are associated with similar or lower rates of major bleeding (MB) compared to warfarin. This study compared risk of MB, including gastrointestinal (GI) bleeding and intracranial hemorrhage (ICH), among non-valvular atrial fibrillation (NVAF) patients initiating DOACs versus warfarin in the US Medicare population. Methods: NVAF patients ≥65 years who initiated apixaban, rivaroxaban, dabigatran or warfarin were selected from the Center for Medicare Services (CMS) database between 01JAN2013-31DEC2014. 1:1 propensity score matching was used to balance demographics and clinical characteristics of each DOAC to warfarin. Cox proportional hazards models were used to estimate the hazard ratio (HR) of MB (identified using primary ICD-9 codes of inpatient claims) between DOACs and warfarin. Results: After matching, apixaban, rivaroxaban, or dabigatran vs. warfarin matched cohorts were balanced with mean age of 77-78 years and CHA2DS2- VASc score of 4.4-4.7. Apixaban and dabigatran initiators had significantly lower risk of MB, while rivaroxaban initiators had higher risk of MB compared to warfarin initiators. Apixaban was associated with significantly lower risk of GI bleeding compared to warfarin. Rivaroxaban was associated with significantly higher risk of GI bleeding compared to warfarin. All DOACs were associated with a lower risk of ICH compared to warfarin (Table). Conclusion: Among Medicare NVAF patients, apixaban and dabigatran were associated with lower risk of MB and rivaroxaban was associated with higher risk of MB compared to warfarin. Apixaban was the only DOAC to show risk reduction for both GI bleeding and ICH compared to warfarin.