Evaluation of Venous Thromboembolism Prevention in High-Risk Trauma Patients: A Prospective Randomized Trial of Standard Enoxaparin Versus Two Anti-Xa Adjusted Dosing Strategies

This is a pilot study to determine if AT-III serum concentrations differ between patients with normal (>= 0.1 IU/mL) versus subtherapeutic (<0.1 IU/mL) anti-Xa trough concentrations when placed on enoxaparin 30 mg twice daily for venous thromboembolism (VTE) prophylaxis. Secondarily, this study will compare two enoxaparin dosing strategies: standard 30 mg twice daily and a dosing strategy based on trough anti-Xa values in high-risk trauma patients.

Specific aims include: 1) to compare the extent of reduced AT-III activity between patients with trough anti-Xa >= 0.1 IU/mL and < 0.1 IU/mL upon initial assay; 2) to determine the proportion of patients who reach goal anti-Xa and the time to goal anti-Xa achievement between two interventional dosing strategies: enoxaparin 40 mg every 12 hours (with consideration to increase to 50 mg every 12 hours if recheck anti-Xa is not at goal) and enoxaparin 30 mg every eight hours; 3) to compare anti-Xa enoxaparin dosing strategies based on VTE, bleeding rates, transfusion requirements, drug discontinuation rate and bioaccumulation, and 4) to determine patient-specific factors that correlate to subtherapeutic anti-Xa such as serial AT-III activity, weight, body mass index, age, cumulative fluid administration, and thromboelastography (TEG).