Warfarin Use, Stroke, and Bleeding Risk among Pre-Existing Atrial Fibrillation US Veterans Transitioning to Dialysis

Abstract

<b><i>Introduction:</i></b> Anticoagulation is commonly used for stroke prevention among patients with atrial fibrillation (AF); however, end-stage renal disease (ESRD) patients on hemodialysis are at higher risk of bleeding and stroke, even without anticoagulation. It is unclear if patients should be continued on anticoagulation at the time of transition to ESRD. In this study, we validated risk scores for stroke and bleeding in this population and assessed risk of stroke and bleeding among warfarin users compared to nonusers. <b><i>Methods:</i></b> We utilized a cohort of 28,620 pre-dialysis US veterans transitioning to hemodialysis between October 2007 and March 2015. Incident rates for the risks of stroke and bleeding were ascertained based upon CHA₂DS₂-VASc or HAS-BLED scores, respectively. A propensity score-based competing risk analysis was used to assess risk of stroke and bleeding. <b><i>Findings:</i></b> The mean age of our cohort was 77 ± 9 years, and the median CHA₂DS₂-VASc and HAS-BLED scores were 7 (5, 8) and 3 (3, 4), respectively. Increasing CHA₂DS₂-VASc and HAS-BLED scores were predictive of increasing stroke and bleeding rates, respectively. However, warfarin use did not appear to affect the risk of stroke and bleeding (p-interaction = 0.84 for stroke and 0.24 for bleeding). Warfarin use was associated with a higher risk of stroke (adjusted SHR 1.44, 95% CI: 1.23–1.69) and a higher risk of bleeding (adjusted SHR 1.38, 95% CI: 1.25–1.52) when accounting for the competing risk of death. <b><i>Discussion:</i></b> There was no difference in incidence rates of stroke or bleeding among warfarin users versus nonusers. Warfarin was associated with a higher risk of stroke and bleeding after considering mortality risk.