Fixed or Weight-Tiered Enoxaparin After Thoracic Surgery for Venous Thromboembolism Prevention

Background. Venous thromboembolism is an important patient safety issue in thoracic surgery patients. The optimal enoxaparin dose remains unclear. This multicenter pre/post clinical trial compared the pharmacokinetics of fixed versus weight-tiered enoxaparin, and their impact on 90-day venous thromboembolism and bleeding. Methods. Thoracic surgery patients were prospectively enrolled using a pre/post study design. Cohort 1 received enoxaparin 40 mg daily, and cohort 2 received a weight-tiered regimen: less than 70 kg received 30 mg daily; 70 kg to 89.9 kg received 40 mg once daily; and 90 kg or more received 50 mg daily. The primary study outcome was peak anti-factor Xa levels in response to fixed or weight-tiered enoxaparin. Secondary outcomes included trough anti-factor Xa, 90-day symptomatic venous thromboembolism, and 90-day clinically relevant bleeding. Results. One hundred thirty-one patients were prospectively enrolled, including 65 in the fixed-dose cohort and 66 in the weight-tiered cohort. No patient was lost to follow-up. Weight-tiered enoxaparin was not significantly more likely to produce adequate anticoagulation (peak anti-factor Xa 0.3 IU/mL or greater) when compared with fixed-dose enoxaparin (44.3% vs 48.2%, P = .67). Weight-tiered enoxaparin was not more likely to avoid over-anticoagulation (peak anti-factor Xa 0.5 IU/mL or greater) when compared with fixed-dose enoxaparin (3.3% vs 3.6%, P = 1.00). The groups had no significant difference in trough anti-factor Xa. Observed rates of 90-day symptomatic venous thromboembolism and clinically relevant bleeding were low (0% and 3.1%, respectively) and were not significantly different between groups. Conclusions. This multicenter pre/post clinical trial did not show a pharmacokinetic advantage to weight-tiered enoxaparin, when compared with fixed-dose enoxaparin, in thoracic surgery patients. (Clinicaltrials.gov identifier: NCT03251963.) (C) 2020 by The Society of Thoracic Surgeons