Anticoagulant activity of enoxaparin and unfractionated heparin for venous thromboembolism prophylaxis in obese patients undergoing sleeve gastrectomy

Background: One risk of bariatric surgery is venous thromboembolism and the optimal strategy to reduce risk requires further clarification.

Objectives: The objectives of this study were to identify antiXa goal attainment with the institutional standard chemoprophylaxis, analyze discordance between antiXa and thrombin generation assay (TGA) in terms of adequacy of anticoagulation, and to identify correlations between patient characteristics or covariates and markers of coagulation status.

Setting: Large academic medical center in Northeastern United States.

Methods: A total of 60 sleeve gastrectomy patients were enrolled in this institutional review board-approved, prospective cohort study. Patients received the institutional standard prophylactic therapy (subcutaneous enoxaparin 40 mg twice daily or unfractionated heparin [UFH]). The UFH dose was weight based, 5000 units (<120 kg) or 7500 units (≥120 kg) every 8 hours. Various measures of coagulation status were measured at or near steady state.

Results: Patients receiving enoxaparin achieved goal antiXa more frequently compared with the UFH group, and statistical significance was demonstrated (93.8 % versus 4.5%, respectively; P < .0001). Target endogenous thrombin potential reduction from baseline was more frequently obtained in the enoxaparin group versus UFH (50% versus 27.7%, respectively; P = .12). AntiXa was below the limit of detection for the majority of UFH patients; while TGA suggested patients did experience anticoagulation at some level of effectiveness. Endogenous thrombin potential change in the enoxaparin group was correlated to several measures of body composition.

Conclusions: Patients receiving enoxaparin achieved goal antiXa more often versus UFH. There was discordance between antiXa and TGA-based assessment of coagulation status. TGA may provide a more robust assessment of the adequacy of chemoprophylaxis.