Comparative Safety and Effectiveness of Apixaban vs. Warfarin in Oral Anticoagulant-Naïve Japanese Patients With Non-Valvular Atrial Fibrillation　― A Retrospective Chart Review Study ―

BACKGROUND: The risk of bleeding and stroke/systemic embolism (SE) events associated with apixaban vs. warfarin among oral anticoagulant-naïve Japanese patients with non-valvular atrial fibrillation (NVAF) has not been well studied in daily clinical practice. METHODS AND RESULTS: Clinical data for 12,090 patients were retrospectively extracted from the medical records of patients with NVAF (aged ≥20 years, creatinine clearance [CrCl] ≥15 mL/min) newly initiated to apixaban or warfarin treatment between January 1, 2010, and December 31, 2017, at 315 general practitioner clinics and 87 hospitals across Japan. After applying propensity score matching, patient characteristics were well-balanced between the apixaban and warfarin groups (4,523 patients each). The incidence rate (per 100 person-years) of major bleeding was lower in the apixaban vs. warfarin group (1.17 vs. 1.64; hazard ratio [HR], 0.71; 95% confidence interval [CI], 0.54-0.93; P=0.01), as was that of stroke/SE (1.14 vs. 1.73; HR, 0.65; 95% CI, 0.50-0.85; P<0.01). When patients were stratified by CrCl (≥50 mL/min and <50 mL/min), the P value for interaction was not statistically significant between subgroups (P=0.31 for major bleeding and P=0.32 for stroke/SE). CONCLUSIONS: The benefit of apixaban over warfarin for the reduction in risk of major bleeding and stroke/SE could be generalizable to daily clinical practice and to patients with reduced renal function.