Evaluation of an Association Between Enoxaparin Dose per Estimated Blood Volume and Clinically Relevant Bleeding in Low-Weight Trauma Patients

Background: The optimal dosing for enoxaparin venous thromboembolism (VTE) prophylaxis in low-weight trauma patients is unknown. Estimated blood volume (EBV) has shown promise as a dose modifier. Objective: To characterize the association of enoxaparin dose per EBV with the prevalence of VTE and bleeding in low-weight trauma patients. Methods: This was a retrospective study of trauma patients admitted over a 4-year period. Included patients were adults weighing <60 kg who received a minimum of 3 consecutive doses of enoxaparin. The primary endpoint was a comparison of enoxaparin dose per EBV in patients experiencing bleeding and VTE. Secondary endpoints included comparisons of dose per body mass index (BMI) and total body weight (TBW) and the ability of dose per EBV to predict clinical endpoints. Subgroup analyses for patients weighing <50 kg were performed for all endpoints. Results: A total of 189 patients were included. Statistical comparisons for VTE were not performed because of low prevalence. The dose of enoxaparin per EBV was not statistically different between patients who did and did not bleed in all analyses. Doses per BMI and TBW were also not statistically different between the groups. In patients weighing <50 kg, numerically higher doses per EBV, BMI, and TBW were noted in patients that bled versus those that did not. Enoxaparin dose per EBV was not a statistically significant predictor of bleeding in logistic regression models. Conclusion and Relevance: No significant associations between enoxaparin dose per EBV, BMI, or TBW and bleeding were noted in the study. Future analyses of EBV and other dose modifiers should consider inclusion of patients weighing <50 kg.