Non-weight-based enoxaparin dosing subtherapeutic in trauma patients

Background We report our experience dosing and monitoring enoxaparin with anti-factor Xa activity (anti-FXaA) levels for venous thromboembolism prophylaxis in trauma patients (TP). Materials and methods TP receiving standard, non-weight-based dosed enoxaparin administered every 12 h for venous thromboembolism prophylaxis with peak anti-FXaA levels measured were prospectively monitored and evaluated and those whose first anti-FXaA levels ≥ or <0.2 IU/mL were compared. Anti-FXaA levels and enoxaparin dose (mg/kg actual body weight) were evaluated for correlation. Results Of the fifty-one TP included, initial anti-FXaA levels were <0.2 IU/mL in 37 (72.5%) whose dose was lower than those within target range (0.38 [0.32-0.42] mg/kg versus 0.45 [0.39-0.48] mg/kg, P = 0.003). Thirty-seven TP achieved anti-FXaA level ≥0.2 IU/mL (23 requiring dose increases) at a dose of 0.49 [0.44-0.54] mg/kg. Correlation between dose and anti-FXaA levels for the initial 51 anti-FXaA levels (r = 0.360, P = 0.009) and for all 103 anti-XaA levels (r = 0.556, P < 0.001) was noted. Conclusions Non-weight-based enoxaparin dosing did not achieve target anti-FXaA levels in most TP. Higher anti-FXaA levels correlated with larger weight-based enoxaparin doses. Weight-based enoxaparin dosing (i.e., 0.5 mg/kg subcutaneously every 12 h) would better achieve target anti-FXaA levels.