Enoxaparin 40 mg Versus 60 mg for Venous Thromboembolism Prophylaxis After Bariatric Surgery: A Systematic Review and Meta-Analysis of Pharmacologic and Clinical Outcomes

Patients undergoing bariatric surgery face an elevated risk of venous thromboembolism (VTE), primarily due to obesity-related hypercoagulability and changes in the pharmacokinetics of anticoagulants. The standard prophylactic dosing of enoxaparin may not be adequate for this group, leading to the consideration of higher or BMI-adjusted dosing regimens. Nevertheless, the comparative efficacy and safety of standard-dose versus higher-dose enoxaparin in the context of bariatric surgery remain unclear.

A systematic review and meta-analysis were performed following the PRISMA 2020 guidelines. Searches were conducted in PubMed, Embase, Scopus, Web of Science, and the Cochrane Library from their inception through September 30, 2025. The review included randomized controlled trials and cohort studies comparing enoxaparin 40 mg with 60 mg for postoperative venous thromboembolism (VTE) prophylaxis in bariatric surgery. Studies utilizing fixed-dose or BMI-tiered dosing strategies were considered eligible. The primary outcome assessed was the achievement of prophylactic anti-factor Xa levels. Secondary outcomes comprised mean anti-factor Xa levels, sub- and supra-prophylactic anti-factor Xa levels, VTE occurrence, bleeding incidents, mortality rates, overall complications, operative duration, and transfusion requirements. Random-effects meta-analyses were conducted.

Ten studies encompassing 1,276 patients (727 receiving 40 mg and 549 receiving 60 mg) were included. Enoxaparin 40 mg was associated with significantly lower mean anti-factor Xa levels compared with 60 mg (MD − 0.08 IU/mL; 95% CI − 0.13 to − 0.03). Patients receiving 40 mg had higher rates of sub-prophylactic anti-Xa levels (RR 1.35; 95% CI 1.03–1.77), whereas 60 mg was associated with increased supra-prophylactic levels (RR 0.25; 95% CI 0.09–0.70). Overall achievement of target prophylactic anti-Xa levels did not differ between doses, although once-daily 40 mg dosing was associated with reduced target attainment compared with once-daily 60 mg. No significant differences were observed in VTE, deep vein thrombosis, pulmonary embolism, bleeding, mortality, overall complications, operative duration, or transfusion requirements.

Although higher enoxaparin doses improved anti-factor Xa levels, this did not translate into reductions in venous thromboembolism, bleeding, or mortality, underscoring the disconnect between pharmacokinetic markers and clinical outcomes in bariatric surgery patients.

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