Efficacy of two escalated enoxaparin dosing regimens in achieving target anti-factor Xa levels for venous thromboembolism prophylaxis among obese, hospitalized patients

Purpose: Due due pharmacokinetic and pharmacodynamic differences, standard enoxaparin dosing regimens may not provide adequate venous thromboembolism prophylaxis in obese hospitalized patients. Both weight-based and fixed-dose escalated prophylaxis regimens have been compared to routine dosing, but no studies have compared the escalated approaches to each other. The purpose of this study is to compare the effects of a weight-based and a fixed-dose escalated enoxaparin dosing regimen on attainment of target anti-Factor Xa levels, a surrogate marker for anticoagulation. Methods: In this prospective, multi-center trial, enoxaparin 0.5 mg/kg daily (weight-based) and enoxaparin 40 mg twice daily (fixed dose) were compared to determine if either resulted in more frequent attainment of anti-Factor Xa levels within the goal range of 0.2-0.5 IU/mL. Patients with a BMI ≥ 40 kg/m2 were included. Exclusion criteria were pregnancy, creatinine clearance < 30 mL/min, and trauma during the index stay. Results: Eighty patients were enrolled in a 1:1 fashion between the weight-based and fixed-dose groups. There were no difference in percent of patients achieving target anti-Factor Xa levels (72.5% in weight-based versus 70.0% in fixed-dose). More patients had sub-therapeutic levels than supra-therapeutic levels. No bleeding or thrombotic events were observed. Conclusions: Both weight-based and fixed-dose escalated enoxaparin dosing regimens appear effective in attaining target anti-Factor Xa levels, and no safety events occurred. Future studies should examine the clinical significance of this finding.