3051Effectiveness and safety of apixaban, dabigatran and warfarin compared to rivaroxaban in non-valvular atrial fibrillation; a Norwegian nationwide cohort study

Abstract

Abstract Introduction Non-vitamin K oral anticoagulants (NOACs) are increasingly used for stroke prevention in patients with non-valvular atrial fibrillation (NVAF). Although proven effective and safe, there is limited knowledge of the comparative effectiveness and safety of the different NOACs in real life. Norway has nationwide registries of good quality, being suitable for doing such a comparison. Purpose The aim of this nationwide cohort study was to compare the risk of stroke/systemic embolism (SE) and major bleeding in patients with NVAF treated with dabigatran, apixaban and warfarin compared with patients treated with rivaroxaban. Methods By merging nationwide registries (the Norwegian Patient Registry and the Norwegian Prescription Database), a cohort was created including all oral anticoagulant (OAC)-naïve adult NVAF patients initiating OAC in the study period 1 Jan 2013 to 31 Dec 2017. The patients were followed until switching of OAC type, discontinuation, death, or end of study-period. Cox proportional-hazards regression was used to estimate adjusted hazard ratios (HRs) for the risk of stroke/SE or bleeding in patients using dabigatran, apixaban and warfarin compared to rivaroxaban. Results A total of 65 563 new users of OAC were included; 10,413 initiated dabigatran, 28,363 apixaban, 13,087 warfarin and 13,700 rivaroxaban. The median age was 71 yrs for dabigatran, 74 yrs for apixaban, 75 yrs for warfarin, and 73 yrs for rivaroxaban; 58.3% were men. Dabigatran-users were younger and had less comorbidities than all other OAC-users; the greatest difference was in the proportion with chronic kidney disease (2.4% in the dabigatran-group versus 7.0%, 12.5%, and 4.6% in the apixaban, warfarin and rivaroxaban groups, respectively). During a median follow-up time of 14.7 months (IQR 4.9–30.6), 2 361 (3.6%) patients suffered a stroke/SE, 2,051 (3.1%) had a major bleeding, and 4 250 (6.5%) died. Adjusted HRs for stroke/SE and major bleeding are presented in the figure. When the risk of stroke/SE and major bleeding was assessed solely in patients that received the standard dose of OAC (73% of NOAC users), the results were similar to the results for the entire population. OACs compared to rivaroxaban Conclusion In this nationwide cohort study of patients with NVAF being new users of OAC, we found no significant differences in risk of stroke/SE between different OACs and rivaroxaban, whereas dabigatran and apixaban were associated with significantly lower risk of major bleeding. Acknowledgement/Funding The study was funded by the South-Eastern Norway Regional Health Authority, and by BMS/Pfizer through the ERISTA program.