Safety and effectiveness of dabigatran and warfarin in routine care of patients with atrial fibrillation

The RE-LY study demonstrated the safety and efficacy of dabigatran relative to warfarin for stroke prevention in non-valvular atrial fibrillation. It is important to further evaluate safety and effectiveness of drugs in routine care. This study used a sequential cohort design with propensity score matching to compare dabigatran with warfarin among patients in two commercial health insurance databases. New users of these anticoagulants were followed from initiation until discontinuation, the end of the study, or the occurrence of a study outcome (primary study outcomes were stroke and major bleeding). Proportional hazards regression was conducted separately within each data source and results were pooled. Among 19,189 matched dabigatran and warfarin initiators (mean age: 68 years, 36 % female), as-treated follow-up (average of 5 months for dabigatran, 4 months for warfarin) identified 62 and 69 strokes, respectively (pooled HR = 0.77; 95 % CI = 0.54 to 1.09), and 354 and 395 major haemorrhages, respectively (HR = 0.75; 0.65 to 0.87). No meaningful heterogeneity was identified across subgroups, but numeric trends suggest more pronounced stroke prevention by dabigatran relative to warfarin among patients age 75+ (HR = 0.57; 0.33 to 0.97) or with < 6 months of use (HR = 0.51; 0.19 to 1.42). Major bleeds were reduced more by dabigatran among patients aged < 55 (HR = 0.51; 0.30 to 0.87) and with CHADS2 < 2 (HR = 0.58; 0.44 to 0.77). In conclusion, in routine care of patients with non-valvular atrial fibrillation, dabigatran treatment resulted in improved health outcomes compared with warfarin.