Safety and Effectiveness of Apixaban Versus Warfarin in Japanese Patients with Nonvalvular Atrial Fibrillation Stratified by Renal Function: A Retrospective Cohort Study

BACKGROUND: We previously conducted a retrospective cohort study using chart review of oral anticoagulant-naïve Japanese patients with nonvalvular atrial fibrillation (NVAF) that assessed the risk of major bleeding and stroke/systemic embolism (SE) events of apixaban versus warfarin. METHODS: In this subgroup analysis, we compared the risk of major bleeding and stroke/SE events by stratifying patients into four subgroups matched 1:1 using propensity score matching (PSM) according to baseline creatinine clearance (CrCl; mL/min): ≥ 15 to < 30, ≥ 30 to < 50, ≥ 50 to < 80, and ≥ 80. RESULTS: Of the 7074 patients in the apixaban group and 4998 in the warfarin group eligible for inclusion in the analysis, 4385 were included in each group after PSM. Incidence rates of major bleeding and stroke/SE events were generally lower with apixaban versus warfarin across the CrCl subgroups. When all patients with a CrCl change of < 0 mL/min per year during the study period (apixaban, n = 3871; warfarin, n = 2635) were stratified into four subgroups based on the magnitude of CrCl decline (median CrCl change [mL/min] per year: − 1.09, − 3.48, − 7.54, and − 36.92 for apixaban, and − 1.10, − 3.65, − 7.85, and − 40.40 for warfarin), the incidence rates of major bleeding and stroke/SE events generally increased with an increasing CrCl decline per year in both groups. CONCLUSIONS: In Japanese patients with NVAF, the safety and effectiveness of apixaban and warfarin were consistent across different renal subgroups, including those with severe renal impairment. Our results highlight the importance of monitoring renal function variations over time in patients with NVAF. CLINICALTRIALS.GOV IDENTIFIER: NCT03765242. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s40256-023-00611-7.