Creatinine Clearance May Predict Goal Enoxaparin Dose in Trauma

Background: Guidelines for enoxaparin dosing after trauma recommend an initial dose of 40mg twice daily for most patients and then adjusting by anti-Xa levels. Previous studies indicated higher enoxaparin doses are necessary with higher creatinine clearance levels (CrCl). We sought to determine if the goal enoxaparin dose correlates with the admission CrCl to reduce the reliance on measuring anti-Xa levels. Study Design: A retrospective review was conducted of patients admitted to an urban, academic Level 1 trauma center from April 2017 to February 2020. Patients started on enoxaparin who reached goal anti-Xa trough levels were included, and patients were excluded if they did not reach goal anti-Xa levels. Data collection included patient demographics, injury characteristics, admission CrCl, and the final enoxaparin dose. CrCl was then correlated with the final enoxaparin dose. Results: Of the 421 patients included, mean age was 46.6 years and 73% were male. The median goal enoxaparin dose was 40mg twice daily. Mean CrCl significantly increased with increasing doses of enoxaparin (20 mg twice daily: 69.2 mL/min, 30 mg twice daily: 89mL/min, 40 mg twice daily:112.8 mL/min, 50 mg twice daily:140.5mL/min, 60 mg twice daily: 147.4 mL/min, and 70mg twice daily: 140 mL/min 69.2.0 mL/min; p<0.01). Conclusions: Admission CrCl may predict the enoxaparin dose required to achieve adequate anti-Xa levels. Our data indicate that CrCl of approximately 70mL/min, 90mL/min, 110mL/min, 140ml/min and 150ml/min may predict the twice daily enoxaparin doses of 20mg, 30mg, 40mg, 50mg, and 60mg respectively. CrCl dosing guidance may reduce the time to goal anti-Xa levels and reduce the frequency of anti-Xa measurements. Further research is necessary, and enoxaparin dosing should continue to be monitored by anti-Xa levels.