Anti-Xa guided enoxaparin dose adjustment improves pharmacologic deep venous thrombosis prophylaxis in burn patients

Patients recovering from burn injury are at high risk of developing deep venous thrombosis (DVT). While 30-mg twice-daily enoxaparin is accepted as the standard prophylactic dose, recent evidence in injured patients suggests this dosing strategy may result in sub-optimal pharmacologic DVT prophylaxis. We hypothesized that standard enoxaparin dosing would result in inadequate DVT prophylaxis in burn patients.

A retrospective review of an ABA-verified Burn center's registry from January 2012 - December 2016 identified patients with peak plasma anti-Xa levels to monitor the efficacy of pharmacologic DVT prophylaxis. Patients ≥18 years old were included if they received at least 3 doses of enoxaparin and had appropriately timed peak anti-Xa levels. We analyzed data including patient demographics, body weight, body mass index (BMI) and total body surface area burn (TBSA). Diagnosis of DVT was collected.

During the study period, 393 patients were screened with a plasma anti-Xa levels. Of the 157 patients that met inclusion criteria, 81 (51.6%) achieved target peak plasma anti-Xa levels (0.2-0.4 IU/mL) on standard 30-mg twice-daily prophylactic enoxaparin and 76 (48.4%) had sub-prophylactic levels. Sub-prophylactic patients were more likely to be male, have increased body weight and elevated BMI. 49 of the 76 sub-prophylactic patients received a dose-adjustment in order to reach target anti-Xa levels; 37 patients required 40mg twice-daily, 10 required 50mg twice-daily and 2 required 60mg twice-daily. The overall DVT rate was 3.8%.

The current recommended prophylactic dose of 30-mg twice-daily enoxaparin is inadequate in many burn patients. Alternate dosing strategies should be considered to increase the number of burn patients achieving target prophylactic anti-Xa levels. Determining whether prophylactic enoxaparin dose adjustment decreases DVT rates in burn injured patients should be evaluated in future prospective trials.