Rivaroxaban Versus Warfarin in African American Patients with Nonvalvular Atrial Fibrillation

INTRODUCTION:Black patients are under-represented in randomized trials evaluating oral anticoagulants in non-valvular atrial fibrillation (NVAF). We sought to evaluate the effectiveness and safety of rivaroxaban versus warfarin in African Americans with NVAF. METHODS:We performed an analysis using Optum® De-Identified Electronic Health Record (EHR) data from 1/1/2012-9/30/2018. We included adult African American patients with a diagnosis of NVAF who were anticoagulant-naïve during the 12-months prior to initiation of rivaroxaban or warfarin. Patients receiving rivaroxaban were 1:1 propensity score matched to warfarin patients. Our primary effectiveness and safety outcomes were the 2-year incidence rates (%/year) of stroke or systemic embolism (SSE) and major bleeding using an intention-to-treat approach. Cohorts were compared using doubly-robust Cox regression and reported as hazard ratios (HRs) with 95% confidence intervals (CIs). RESULTS:We matched 4102 rivaroxaban and 4102 warfarin users with a median (interquartile range) available follow-up of 2.0 (0.9, 2.0) years. Median CHA2DS2-VASc and HASBLED scores were 3 (2, 4) and 2 (1, 3). Rivaroxaban use was associated with a lower risk of SSE (1.99 versus 2.48, HR = 0.77, 95%CI = 0.60-0.99), ischemic stroke (1.84 versus 2.37, HR = 0.76, 95%CI = 0.59-0.98) and major bleeding (4.22 versus 4.98, HR = 0.84, 95%CI = 0.70-0.99). No differences in intracranial hemorrhage or gastrointestinal bleeding were observed. Neither sensitivity analyses utilizing an on-treatment methodology nor inverse probability-of-treatment weighting showed significant differences in SSE or major bleeding between rivaroxaban and warfarin users. CONCLUSIONS:Rivaroxaban appeared at least as effective and safe as warfarin when used to manage African American patients with NVAF in routine practice.