Evaluation of a novel blood volume–based enoxaparin dosing guideline for venous thromboembolism prophylaxis in trauma patients

Abstract Purpose Fixed-dose and body mass index (BMI)–based enoxaparin regimens provide inadequate venous thromboembolism (VTE) prophylaxis for many trauma patients. The purpose of this study was to evaluate the effectiveness of a novel blood volume (BV)–based enoxaparin guideline vs a historical BMI-based guideline for VTE prophylaxis in trauma patients. Methods This was a retrospective pre/post study completed at a large academic level 1 trauma center. All adult trauma patients admitted from October through December 2019 and August through October 2020 who received prophylactic enoxaparin per guideline were included. The BV dosing was as follows: patients with a BV of 3 to 4.9 L received enoxaparin 30 mg every 12 hours, those with a BV of 5 to 6.9 L received 40 mg every 12 hours, and those with a BV of ≥7 L received 60 mg every 12 hours. The primary outcome was the percentage of patients who attained a target anti–factor Xa (anti-Xa) postdosing level at the first steady-state assessment (0.2 to 0.5 IU/mL). Results A total of 241 patients (99 for the BMI group and 142 for the BV group) were included. The study groups had a median age of 38 vs 42 years, a mean BMI of 27.4 vs 27.7 kg/m2, and a mean BV of 5.1 vs 5.1 L, respectively. A total of 63 patients (62.6%) in the BMI group attained target anti-Xa levels compared to 115 patients (81%) in the BV group (P = 0.008). In multivariate regression, the BV-based guideline was the only variable associated with attainment of target anti-Xa levels (adjusted odds ratio, 2.02; P = 0.01). Clinically relevant bleeding and VTE rates were similar between the groups. Conclusion Dosing prophylactic enoxaparin using a BV-based dosing guideline significantly increased attainment of target anti-Xa levels.