Dabigatran and Warfarin in Vitamin K Antagonist–Naive and –Experienced Cohorts With Atrial Fibrillation

Abstract

Background—: The comparison of anticoagulants dabigatran and warfarin might be most equitable in vitamin K antagonist (VKA)–naive patients. Methods and Results—: Warfarin and 2 doses of dabigatran—110 mg BID (D110) and 150 mg BID (D150)—were compared in a balanced population of VKA-naive (≤62 days of lifetime VKA exposure, with 33% never prescribed a VKA) and VKA-experienced patients with atrial fibrillation (n=18 113). For VKA-naive and -experienced patients assigned warfarin, the time in therapeutic range (international normalized ratio 2.0 to 3.0) was 62% and 67%, respectively, and 61% and 66% for those never and ever prescribed a VKA. In VKA-naive patients, stroke and systemic embolism rates were 1.57%, 1.07%, and 1.69% per year for D110, D150, and warfarin, respectively. D110 was similar to warfarin ( P =0.65); D150 was superior ( P =0.005). Major bleeding rates were 3.11%, 3.34%, and 3.57% per year, respectively. D110 and D150 were similar to warfarin ( P =0.19 and P =0.55). Intracranial bleeding rates were 0.19%, 0.33%, and 0.73% per year, respectively. D110 and D150 were lower than warfarin ( P <0.001 and P =0.005). In VKA-experienced patients, stroke and systemic embolism rates were 1.51%, 1.15%, and 1.74% per year for D110, D150, and warfarin, respectively. D110 was similar to warfarin ( P =0.32); D150 was superior ( P =0.007). Major bleeding rates were 2.66%, 3.30%, and 3.57% per year, respectively. D110 was lower than warfarin ( P =0.003); D150 was similar ( P =0.41). Intracranial bleeding rates were 0.26%, 0.32%, and 0.79% per year, respectively. D110 and D150 were lower than warfarin ( P <0.001 for both). Results were similar for patients never on a VKA. Conclusions—: Previous VKA exposure does not influence the benefits of dabigatran at either dose compared with warfarin. Clinical Trial Registration—: http://www.clinicaltrials.gov . Unique identifier: NCT00262600.