Impact of Weight on Anti-Xa Attainment in High-Risk Trauma Patients on Enoxaparin Chemoprophylaxis.

Abstract Background Serum anti-factor Xa (anti-Xa) concentration may guide low molecular weight heparin chemoprophylaxis in trauma patients. Higher total body weight (TBW) is a risk factor for subprophylactic anti-Xa and venous thromboembolism (VTE). The purpose of this study was to evaluate TBW differences in patients with subprophylactic versus prophylactic trough anti-Xa. Methods This retrospective study included adults admitted to the trauma service who received enoxaparin chemoprophylaxis, trough anti-Xa assessment, and screening duplex ultrasound. Initial enoxaparin dose was determined per trauma team weight-tiered protocol with subsequent 10 mg increase if anti-Xa was subprophylactic. Patients were stratified into subprophylactic (anti-Xa Results A total of 887 patients were included with 681 (76.8%) having subprophylactic anti-Xa. The subprophylactic group had significantly younger age, higher proportion male sex, higher Injury Severity Score (ISS), higher BMI, and longer length of hospital stay. The subprophylactic group had higher TBW (median [IQR], 87.8 [74-102] kg vs. 78.9 [68-91.8] kg; P Conclusions TBW is higher and weight-adjusted enoxaparin dose is lower in high-risk trauma patients with subprophylactic anti-Xa concentrations. These data suggest TBW should be considered when determining the optimal prophylactic enoxaparin dose in high-risk trauma patients.