Comparative effectiveness and safety of warfarin and dabigatran in patients with non-valvular atrial fibrillation in Japan: A claims database analysis

BACKGROUND: Antithrombotic therapy, including direct oral anticoagulants, is recommended in patients with non-valvular atrial fibrillation (NVAF) who are at intermediate-to-high risk of stroke. The aims of this study were to assess the patterns of oral anticoagulant (OAC) prescription in Japanese patients with NVAF and compare the effectiveness and safety of dabigatran and warfarin. METHODS: This was a retrospective observational study of adults with NVAF who initiated dabigatran or warfarin between March 14, 2011 and June 30, 2016, using electronic claims data of approximately 12.94 million patients from 230 hospitals. Propensity score matching was used to derive equal patient cohorts. Outcomes included the combined incidence of stroke, systemic embolism, and intracranial bleeding (primary endpoint) and the incidence of major bleeding (secondary endpoint). RESULTS: Overall, 400,884 patients were included. Among those prescribed an OAC, warfarin was the most common (34.3%). For the comparison of dabigatran and warfarin, 4606 patients were propensity-score matched in each cohort. Dabigatran recipients had lower incidences of stroke, systemic embolism, and intracranial bleeding [29.0 vs. 35.6 per 1000 patient-years; hazard ratio (HR), 0.72; 95% confidence interval (CI): 0.53-0.97; p=0.031] and major bleeding (6.4 vs. 11.3 per 1000 patient-years; HR, 0.55; 95% CI: 0.30-0.99; p=0.048). The most common type of bleeding in both groups was gastrointestinal and the incidence was lower in dabigatran recipients (1.6 vs. 6.4 per 1000 patient-years; HR, 0.24; 95% CI: 0.08-0.69; p=0.009). CONCLUSIONS: In Japan, dabigatran was associated with a lower risk of stroke, systemic embolism, and intracranial bleeding and major bleeding compared with warfarin in patients with NVAF.