Safety and Effectiveness of Apixaban Versus Warfarin in Peritoneal Dialysis Patients with Newly Diagnosed Nonvalvular Atrial Fibrillation

Introduction Apixaban reduces thromboembolic events, bleeding, and mortality compared with warfarin in patients with nonvalvular atrial fibrillation (NVAF). However, evidence in patients with kidney failure (KF) receiving peritoneal dialysis (PD) is limited. We evaluated the safety and effectiveness of apixaban versus warfarin in this population. Methods Using the US Renal Data System, we identified Medicare beneficiaries on PD with newly diagnosed NVAF (2014–2019) who had no prior oral anticoagulation (OAC) use. We included patients initiating apixaban or warfarin within 30 days after NVAF diagnosis. After propensity matching we estimated the hazard ratios for thromboembolic events, bleeding events, and mortality using Cox models accounting for competing risks, where applicable, and using both intent-to-treat and as-treated approaches. Results Among 6,571 OAC-naive PD patients with newly-diagnosed NVAF, 334 initiated apixaban and 717 initiated warfarin within 30 days. After 1:1 propensity matching, all observed characteristics of 330 apixaban and 330 warfarin users were balanced. The median CHA₂DS₂-VASc score was 4 (IQR 3-5). In intent-to-treat analyses, hazards of ischemic stroke (HR=0.92; 95%CI, 0.42-2.01) and the composite of other thromboembolic outcomes with cardiovascular death (HR=0.90; 95%CI, 0.66-1.22) did not differ between groups. The hazards of clinically important bleeding (HR=0.81; 95%CI, 0.62-1.07), major bleeding, intracranial hemorrhage, and all-cause mortality also did not differ between groups. Findings were consistent in as-treated analyses. Discussion Among PD patients with newly-diagnosed NVAF, we observed no statistically significant differences between apixaban and warfarin for effectiveness or bleeding outcomes. Given the challenges of warfarin management in KF, apixaban may represent a more practical option when anticoagulation is pursued.