Weight-Based Dosing for Low-Molecular-Weight Heparin (Enoxaparin) Administration to Achieve Optimal VTE Prophylaxis in Trauma Patients

Introduction: Patients admitted after traumatic injuries are at high risk for developing venous thromboembolism (VTE). Low-molecular-weight heparin (LMWH) is commonly used to prevent VTE in this patient population; however, the optimal dosing strategy has yet to be determined. To address this question, a fixed-dosing strategy of LMWH was compared to a weight-based dosing strategy of LMWH for VTE prophylaxis. Methods: A retrospective, pre-post implementation cohort study compared a fixed vs a weight-based dosing strategy of LMWH for VTE prophylaxis. Patients admitted to our level 1 trauma center were included if they had an estimated glomerular filtration rate >30 mL/min/1.73 m(2), received at least 3 doses of LMWH, and had an appropriately drawn anti-Xa level on their initial dosing regimen. Patients in the pre-cohort received 30 mg LMWH subcutaneously twice daily as the initial dosing regimen. Patients in the post-cohort received .5 mg/kg (max 60 mg) LMWH subcutaneously every 12 h as the initial dosing regimen. A goal anti-Xa of .2-.4 IU/mL was targeted for prophylaxis. Results: There were 817 patients in the fixed-dosing group (FDG) and 874 patients in the weight-based dosing group (WBDG). In the FDG, 42.8% of the patients achieved the goal initial anti-Xa level, with 54.1% and 3.1% reaching sub- and supratherapeutic doses, respectively. In the WBDG, 66.5% of patients reached goal initial anti-Xa levels, with 23.5% and 10.1% at sub- and supratherapeutic levels. The distribution of dose ranges was significantly different between the dosing strategies (P-value <.001). There was no difference in the number of patients who received blood products (39.1% vs 41.7%. P-value = .299). Conclusions: In our study, weight-based dosing of LMWH yielded a significantly higher proportion of patients who achieved goal prophylactic anti-Xa levels than fixed-dosing of LMWH. Larger-scale studies are needed to assess the risk of VTE events and bleeding with these dosing strategies.