Comparison of effectiveness and safety of treatment with apixaban vs. other oral anticoagulants among elderly nonvalvular atrial fibrillation patients

Objective: To compare the risk of stroke/systemic embolism (S/SE) and major bleeding (MB) of elderly (>= 65 years of age) nonvalvular atrial fibrillation (NVAF) patients initiating apixaban vs. rivaroxaban, dabigatran, or warfarin. Methods: NVAF patients with Medicare Advantage coverage in the US initiating oral anticoagulants (OACs, index event) were identified from the Humana database (1 January 2013-30 September 2015) and grouped into cohorts depending on OAC initiated. Propensity score matching (PSM), 1: 1, was conducted among patients treated with apixaban vs. each other OAC, separately. Rates of S/SE and MB were evaluated in the follow-up. Cox regressions were used to compare the risk of S/SE and MB between apixaban and each of the other OACs during the follow-up. Results: The matched pairs of apixaban vs. rivaroxaban (n = 13,620), apixaban vs. dabigatran (n = 4654), and apixaban vs. warfarin (n = 14,214) were well balanced for key patient characteristics. Adjusted risks for S/SE (hazard ratio [HR] vs. rivaroxaban: 0.72, p <.003; vs. warfarin: 0.65, p <. 001) and MB (HR vs. rivaroxaban: 0.49, p <.001; vs. warfarin: 0.53, p <.001) were significantly lower during the follow-up for patients treated with apixaban vs. rivaroxaban and warfarin. Adjusted risks for S/SE (HR: 0.78, p = .27) and MB (HR: 0.82, p = .23) of NVAF patients treated with apixaban vs. dabigatran trended to be lower, but did not reach statistical significance. Conclusions: In the real-world setting after controlling for differences in patient characteristics, apixaban is associated with significantly lower risk of S/SE and MB than rivaroxaban and warfarin, and a trend towards better outcomes vs. dabigatran among elderly NVAF patients in the US.