Dose adjusting enoxaparin is necessary to achieve adequate venous thromboembolism prophylaxis in trauma patients

Standard venous thromboembolism (VTE) prophylaxis with enoxaparin results in inadequate protection in certain patients, with subtherapeutic plasma anti-Xa levels associated with elevated VTE rates. We hypothesized that many trauma patients would be subtherapeutic on the standard prophylactic dose of enoxaparin. Our goal was to adjust the enoxaparin dose to achieve target anti-Xa levels to take advantage of the drug based on its pharmacologic properties.

Patients admitted to the trauma service were included if they received at least three doses of prophylactic enoxaparin and underwent at least two screening venous duplex. Peak plasma anti-Xa levels of 0.2 IU/mL or less were considered low, and the dose was increased by 10 mg twice daily until adequate anti-Xa levels were obtained. A strict screening venous duplex protocol was followed. Patients were excluded if they were diagnosed with a deep venous thrombosis before beginning enoxaparin or did not have correctly timed anti-Xa levels.

Sixty-one trauma patients met inclusion criteria. There were three patients diagnosed with VTE (4.9%). Patients had a mean age of 45.9 years and were predominantly male (70.5%). Of the 61 patients, 18 (29.5%) had therapeutic anti-Xa levels on standard enoxaparin 30 mg twice daily. Compared with patients who had therapeutic anti-Xa levels on enoxaparin 30 mg twice daily, the 43 patients (70.5%) who were subtherapeutic were more likely to be male, have greater body weight, and larger body surface area. There were no significant bleeding events in the group that received an enoxaparin dose adjustment.

Most patients had subtherapeutic anti-Xa levels while on enoxaparin 30 mg twice daily, suggesting inadequate VTE prophylaxis. The need for routine use of a higher dose of prophylactic enoxaparin in trauma patients and the effects of routinely dose adjusting enoxaparin on VTE rates should be the study of future prospective, randomized trials.

Therapeutic study, level IV.