Effectiveness and safety of non-vitamin K antagonist oral anticoagulants and warfarin in atrial fibrillation: a scandinavian population-based cohort study.

2021 
Aims Using Scandinavian population-based registries, we assessed risk of stroke/systemic embolism (SE) and bleeding with non-vitamin K antagonist oral anticoagulants compared with warfarin in oral anticoagulation-naive patients with atrial fibrillation (AF). Methods and results This historical cohort study included 219,545 AF patients (median age, 74 years; 43% women; mean CHA2DS2-VASc score 3.3) initiating apixaban, dabigatran, rivaroxaban, or warfarin in Denmark, Norway, and Sweden 01JAN2013-31DEC2016. The primary endpoints were stroke/SE and major bleeding. The median follow-up times were 9.7 (3.9-21.5) months for stroke/SE and 9.6 (3.8-21.3) months for bleeding. Apixaban and warfarin initiators were older and had higher CHA2DS2-VASc scores compared with dabigatran and rivaroxaban initiators. After 1:1 propensity score matching, three cohorts were created: apixaban-warfarin (n = 111,162), dabigatran-warfarin (n = 56,856), and rivaroxaban-warfarin (n = 61,198). Adjusted hazard ratios (HRs) were estimated using a Cox regression. For stroke/SE, adjusted HRs against warfarin were 0.96 (95% confidence interval [CI], 0.87-1.06) for apixaban; 0.89 (95% CI, 0.80-1.00) for dabigatran; and 1.03 (95% CI, 0.92-1.14) for rivaroxaban. For major bleeding, the HRs against warfarin were 0.73 (95% CI, 0.67-0.78) for apixaban; 0.89 (95% CI, 0.82-0.97) for dabigatran; and 1.15 (95% CI, 1.07-1.25) for rivaroxaban. The results in the dabigatran cohort did not hold in all dosedefined subgroups. Conclusions In this large Scandinavian study among AF patients initiating oral anticoagulation, those initiating dabigatran, apixaban, and rivaroxaban had similar rates of stroke/SE as patients initiating warfarin. Rates of major bleeding were lower with apixaban and dabigatran and higher with rivaroxaban, each compared with warfarin.
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