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Analysis of the Risks of Stroke, Bleeding and Death in Elderly Patients with Nonvalvular Atrial Fibrillation who Received Various Oral Anticoagulants under the Program Medicare, USA

Nonvitamin K antagonist oral anticoagulants (NOACs) are widely used in patients with nonvalvular atrial fibrillation. There were numerous studies in which NOACs were investigated and compared with warfarin; however, no randomized trials were performed to compare efficacy and safety of various NOACs with each other. We announce a cohort study of a large group of patients with nonvalvular atrial fibrillation who were allocated to warfarin (n = 183,318) or a standard dose of dabigatran (150 mg twice daily; n = 86,198), rivaroxaban (20 mg once daily; n = 106,389), or apixaban (5 mg twice daily; n = 73,039) under the program Medicare in the period from October 2010 to September 2015. Primary outcomes were stroke, bleeding and death. Hazard ratios (HR) and 95% confidence intervals (CI) for the outcomes were estimated using Cox proportional hazards regression. Each of the studied NOAC was compared with warfarin and with each other. All the subjects had similar baseline characteristics. Moreover, patient groups were balanced for all covariates (age, gender, comorbidities etc). Dabigatran, rivaroxaban, and apixaban were associated with lower risk of thromboembolic stroke, bleeding and death compared with warfarin, so their benefit-harm ratio was more favorable than that of warfarin. The risk of stroke was similar for all the studied NOACs, but the risk of bleeding and death was higher for rivaroxaban. This allows for the conclusion that dabigatran and apixaban had more favorable benefit-harm ratio than rivaroxaban.