Factor Xa inhibitors versus warfarin in severely obese patients with venous thromboembolism or atrial fibrillation

Abstract

Objectives: Clinical data for the safety and efficacy of Factor Xa (FXa) inhibitors in severely obese patients is limited. Additional information is needed to assess the risks and benefits of using FXa inhibitors in this patient population. Materials and Methods: A single-center and retrospective chart review was conducted in severely obese patients (body mass index [BMI] >40 kg/m2 or weight >120 kg), who received rivaroxaban, apixaban or warfarin for venous thromboembolism (VTE) treatment or prevention of stroke and systemic embolism in non-valvular atrial fibrillation (AF). The primary endpoint was treatment failure, defined as recurrent VTE in VTE treatment or stroke, transient ischemic attack or systemic embolism in AF within one year of anticoagulation initiation. Secondary endpoints included a composite of major bleeding rates and clinically relevant non-major bleeding (CRNMB) rates. Results: Seventy-three patients were included in the final analysis consisting of 43 patients in the FXa inhibitor arm (apixaban [n = 33] and rivaroxaban [n = 10]) and 30 patients in the warfarin arm. The rate of treatment failure was similar between the FXa inhibitor and warfarin groups (4.7% vs. 6.7%; P = 0.814). Although not statistically significant, major bleeding and CRNMB occurred less frequently in patients receiving FXa inhibitors compared to warfarin (9.3% vs. 23.3%; P = 0.182). Subgroup analysis in patients with BMI >50 kg/m2 or weight >150 kg demonstrated similar efficacy and safety outcomes. The use of non-recommended dosing was more common in the apixaban group compared to the rivaroxaban group. Conclusion: FXa inhibitors (apixaban and rivaroxaban) appear to have similar efficacy and safety compared to warfarin in severely obese patients. Larger prospective studies are needed to confirm these results.