PB0410 - Clinical Outcomes of Enoxaparin 30 mg for Venous Thromboembolic Prophylaxis in Low-Weight Surgical Patients: A Retrospective Cohort Study

Background: Enoxaparin is indicated for venous thromboembolism (VTE) prophylaxis at a standard daily dose of 40 mg. The risk of bleeding in low-weight patients ( < 45 kg for females and < 57 kg for males) is higher when receiving the standard dose of enoxaparin. Therefore, a 30 mg daily dose of Enoxaparin has been used in VTE prophylaxis in low-weight patients. Studies assessing the clinical outcomes of this thromboprophylaxis dose are lacking.

Aims: To assess the effectiveness and safety of enoxaparin 30 mg thromboprophylaxis in low-weight surgical patients.

Methods: This single-centre, retrospective cohort study included low-weight patients who underwent non-cardiac, non-orthopaedic surgery and received enoxaparin 30 mg daily for thromboprophylaxis from January 2018 to August 2023. Developing VTE within 90 days and major bleeding 30 days postoperatively were assessed as study objectives. Risk factors for developing VTE and major bleeding were examined using univariable logistic regression. Covariates with P < 0.1 were entered into a multivariable logistic regression.

Results: A total of 124 patients were included; five (4%) developed VTE as follows: two patients developed a concomitant pulmonary embolism and deep vein thrombosis (DVT), and three developed DVT. Major bleeding developed in 6 (4.8%) patients, with no fatalities or bleeding in any critical organ. The overall bleeding included major and clinically relevant non-major bleeding was observed in 21 (16.9%) patients. Univariate regression analysis revealed that lower patient weight (OR 0.9, 95% CI 0.8-0.9, P=0.01) and baseline hemoglobin levels (OR 0.9, 95% CI 0.9-1, P=0.05) were associated with the risk of developing overall bleeding. Testing these factors in a multivariate regression analysis was not associated with developing overall bleeding. Undergoing surgery for more than 45 minutes was a risk factor for developing clinically relevant non-major bleeding (P=0.038).

Conclusion(s): Using enoxaparin 30 mg daily dose for thromboprophylaxis in low-weight surgical patients is effective, with an acceptable rate of major bleeding.