Safety and Efficacy of High-Dose Unfractionated Heparin Versus High-Dose Enoxaparin for Venous Thromboembolism Prevention in Morbidly Obese Hospitalized Patients

Abstract

Venous thromboembolism is a cause of morbidity and mortality in hospitalized patients, and morbid obesity increases this risk. Various prophylaxis dosing strategies have been investigated. However, it is unclear if high-fixed dose enoxaparin or high-fixed dose unfractionated heparin thromboprophylaxis is optimal for minimizing the incidence of major bleeding and reducing hospital-acquired venous thromboembolism. A single-center retrospective observational study was conducted in hospitalized patients who were morbidly obese (body mass index ≥40 kg/m2) and who received either high-fixed dose enoxaparin (40 mg every 12 hours) or unfractionated heparin (7500 units every 8 hours) for venous thromboembolism prophylaxis. Co-primary outcomes included incidence of major bleeding and venous thromboembolism diagnosed during hospitalization. Predictors of major bleeding were evaluated by multivariable regression. In the 305 patients included (n=190 unfractionated heparin, n=115 enoxaparin), the incidence of major bleeding was significantly higher in the unfractionated heparin group (odds ratio [OR] 1.85, 95% confidence interval [CI] 1.07-3.13; P=0.025), with no significant difference in the incidence of venous thromboembolism diagnosed during hospitalization. The only independent predictors of major bleeding were intensive care acuity (OR 3.32, 95% CI 1.91-5.78; P <0.001) and selection of unfractionated heparin rather than enoxaparin for venous thromboembolism prophylaxis (OR 2.16, 95% CI 1.22-3.82; P=0.008). High-fixed dose unfractionated heparin for venous thromboembolism prophylaxis may lead to a higher risk of major bleeding events compared with high-fixed dose enoxaparin in patients who are morbidly obese.