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Comparative Stroke, Bleeding, and Mortality Risks in Older Medicare Patients Treated with Oral Anticoagulants for Nonvalvular Atrial Fibrillation

Nonvitamin K antagonist oral anticoagulants (NOACs) are alternatives to warfarin in patients with nonvalvular atrial fibrillation. Randomized trials compared NOACs with warfarin, but none have compared individual NOACs against each other for safety and effectiveness.

Methods

We performed a retrospective new-user cohort study of patients with nonvalvular atrial fibrillation enrolled in US Medicare who initiated 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) between October 2010 and September 2015. Propensity score-adjusted Cox proportional hazards regression was used to estimate adjusted hazard ratios (HR) and 95% confidence intervals (CI) for the outcomes of thromboembolic stroke, intracranial hemorrhage, major extracranial bleeding, and all-cause mortality, comparing each NOAC with warfarin, and with each other NOAC.

Results

Compared with warfarin, each NOAC was associated with reduced risks of thromboembolic stroke (20%-29% reduction; P = .002 [dabigatran], P < 0.001 [rivaroxaban, apixaban]), intracranial hemorrhage (35%-62% reduction; P < 0.001 [each NOAC]), and mortality (19%-34% reduction; P < .001 [each NOAC]). The NOACs were similar for thromboembolic stroke but rivaroxaban was associated with increased risks of intracranial hemorrhage (vs dabigatran: HR = 1.71; 95% CI, 1.35-2.17), major extracranial bleeding (vs dabigatran: HR = 1.32; 95% CI, 1.21-1.45; vs apixaban: HR = 2.70; 95% CI, 2.38-3.05), and death (vs dabigatran: HR = 1.12; 95% CI, 1.01-1.24; vs apixaban: HR = 1.23; 95% CI, 1.09-1.38). Dabigatran was associated with reduced risk of intracranial hemorrhage (HR = 0.70; 95% CI ,0.53-0.94) and increased risk of major extracranial bleeding (HR = 2.04; 95% CI, 1.78-2.32) compared with apixaban.

Conclusions

Among patients treated with standard-dose NOAC for nonvalvular atrial fibrillation and warfarin users with similar baseline characteristics, dabigatran, rivaroxaban, and apixaban were associated with a more favorable benefit–harm profile than warfarin. Among NOAC users, dabigatran and apixaban were associated with a more favorable benefit–harm profile than rivaroxaban.

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-David J. Graham, MD, MPHa, Elande Baro, PhDb, Rongmei Zhang, PhDb, Jiemin Liao, MAc, Michael Wernecke, BAc, Marsha E. Reichman, PhDa, Mao Hu, BSc, Onyekachukwu Illoh, OD, MPHa, Yuqin Wei, MSc, Margie R. Goulding, PhDa, Yoganand Chillarige, MPAc, Mary Ross Southworth, PharmDd, Thomas E. MaCurdy, PhDc,e, Jeffrey A. Kelman, MD, MMScf

This article originally appeared in the May 2019 issue of The American Journal of Medicine.

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