Creatinine clearance predicts the goal enoxaparin dose in traumatic brain injury

Patients with traumatic brain injury (TBI) are at high risk of venous thromboembolism (VTE). Recent guidelines recommend starting TBI patients on enoxaparin 30 mg twice daily and then considering weight-based dosing. Creatinine clearance may be better than weight for patients when considering high and low enoxaparin dose requirements. We hypothesize that creatinine clearance (CrCl) predicts goal enoxaparin dose better than weight-based dosing.

A retrospective review was conducted on patients admitted to an urban, academic Level I trauma center from August 2017 to February 2020. Patients were included if greater than 18 years, admitted longer than 48 hours, and head and neck AIS ≥ 3. Patients were excluded if they did not have TBI, if they received deep vein thrombosis prophylaxis other than enoxaparin 12-hour dosing, if no anti-Xa levels were drawn, or if the goal anti-Xa level was not reached. Patients were grouped into dosing cohorts based on dose of enoxaparin required to reach goal. Pearson's correlation was used to compare mean CrCl and mean weight across dosing cohorts.

A total of 120 patients met inclusion and exclusion criteria, mean age was 47 years and 68% of patients were male. The mean hospital length of stay was 24 days. There were 5 (4.2%) deep vein thrombosis, no pulmonary embolism, and 5 (4.2%) patients died. Mean CrCl increased significantly with increased dosing of enoxaparin, Pearson's correlation coefficient of 0.484 ( p < 0.001). Weight on admission also increased with increasing enoxaparin dose requirements, with Pearson's correlation coefficient of 0.411 ( p < 0.001).

Creatine clearance predicts goal enoxaparin dose in TBI better than a weight-based dosing strategy. Further research with a larger patient population is required to validate CrCl values to guide enoxaparin dosing.

Prognostic and Epidemiological; Level IV.