Comparing DOAC and warfarin outcomes in an obese population using the 'real-world' Michigan Anticoagulation Quality Improvement Initiative (MAQI2) registry.

Introduction: Direct oral anticoagulants (DOACs) have overtaken warfarin in the treatment of nonvalvular atrial fibrillation (AF) and venous thromboembolism (VTE). Limited data explore the safety of DOACs in obesity.

Methods: This multicenter retrospective study between June 2015 and September 2019 uses the Michigan Anticoagulation Quality Improvement Initiative (MAQI²) registry to compare DOACs and warfarin across weight classes (not obese: body mass index (BMI) ⩾ 18.5 and < 30; obese: BMI ⩾ 30 and < 40; severely obese: BMI ⩾ 40). Primary outcomes include major, clinically relevant nonmajor (CRNM), and minor bleeding events per 100 patient-years. Secondary outcomes include stroke, recurrent VTE, and all-cause mortality.

Results: DOACs were prescribed to 49% of the 4089 patients with AF and 46% of the 3162 patients with VTE. Compared to patients treated with warfarin, those treated with DOACs had a higher estimated glomerular filtration rate across BMI categories regardless of indication. In the AF population, severely obese patients treated with DOACs had more major (3.4 vs 1.8, p = 0.004), CRNM (8.6 vs 5.9, p = 0.019), and minor bleeding (11.4 vs 9.9, p = 0.001). There was no difference in stroke or all-cause mortality. In the VTE population, both CRNM (7.5 vs 6.7, p = 0.042) and minor bleeding (19.3 vs 10.5, p < 0.001) events occurred at higher rates in patients treated with DOACs. There was no difference in recurrent pulmonary embolism, stroke, or all-cause mortality.

Conclusion: There is a higher rate of bleeding in severely obese patients with VTE and AF treated with DOACs compared to warfarin, without a difference in secondary outcomes. Further studies to compare the anticoagulant classes and understand bleeding drivers in this population are needed.