2025 Southeastern Residency Conference

Title: Safety and Efficacy of Direct-acting Oral Anticoagulants versus Warfarin in the Treatment of Venous Thromboembolism in Severely Obese Patients


Authors: Olukemi Omotola, Madeline Shepherd, Evelyn Grafton


Objective: This study aims to compare the efficacy and safety of DOACs, particularly apixaban and rivaroxaban, versus warfarin in patients with severe obesity diagnosed with VTE.


Background: Venous thromboembolism (VTE), encompassing deep vein thrombosis (DVT) and pulmonary embolism (PE), is a serious and potentially life-threatening condition. Anticoagulation therapy is the cornerstone of treatment for VTE to prevent clot progression, recurrence, and associated complications. Traditionally, warfarin has been the mainstay of treatment; however, direct-acting oral anticoagulants (DOACs), such as apixaban and rivaroxaban, have gained widespread use. In contrast to warfarin, their fixed dosing, fewer drug interactions, and lack of routine laboratory monitoring requirements make DOACs an appealing alternative. In the general population, DOACs have demonstrated non-inferior or superior efficacy and safety profiles compared to warfarin for the treatment of VTE. However, data is limited regarding their use in patients with severe obesity, defined as a body mass index (BMI) ≥ 40 kg/m². Given the growing prevalence of obesity, determining the safest and most effective anticoagulation strategies in this population is critical. 


Methods: This was a retrospective chart review of adult patients with a BMI of > 40 kg/m2 who received either apixaban, rivaroxaban, or warfarin for the treatment of venous thromboembolism from January 1, 2019 to September 30, 2024. Patients were excluded if they were pregnant or breastfeeding, had known hypersensitivity or contraindications to one of the study drugs, experienced active bleeding within 6 months of the start of the study time frame, had a history of a known hypercoagulable state, or if they received a fibrinolytic, mechanical thrombectomy, or underwent EkoSonic endovascular system (EKOS) procedure. The primary endpoint was VTE recurrence within one year. Secondary endpoints included major bleeding occurrence, clinically relevant non-major bleeding (as defined by the International Society of Thrombosis and Hemostasis), and all-cause mortality at one year. 


Results: The study included 76 patients, with 60 in the DOAC group and 16 in the warfarin group. For the primary outcome, 6 patients (10%) in the DOAC group experienced VTE recurrence versus 2 patients (12.5%) in the warfarin group (p=0.3186).  In the DOAC group, 3 patients (5%) experienced a major bleeding event, compared to 1 patient (6.3%) in the warfarin group (p= 0.4268). Two patients (3.3%) in the DOAC group experienced clinically relevant non-major bleeding, while no patients in the warfarin group had this type of bleeding event (p= 0.6211).  Finally, in the DOAC group, there were no reported deaths, while in the warfarin group, 2 patients (12.5%) died (p= 0.0421), making this the only statistically significant finding in the study.


Conclusion: DOACs are a safe and effective alternative to warfarin for treating VTE in severely obese patients. Given their comparable efficacy and lower all-cause mortality, DOACs may be a preferred choice in clinical practice.