Enoxaparin versus unfractionated heparin for venous thromboembolism prophylaxis in critically ill patients: A propensity score-adjusted analysis

Abstract

Background: There is limited evidence that guides the choice between heparins for thromboprophylaxis in critically ill patients. The objective of this study was to compare enoxaparin with unfractionated heparin (UFH) as a prophylactic strategy in the intensive care unit (ICU). Methods: This was a prospective cohort study (N=798) that evaluated the incidence of symptomatic venous thromboembolism (VTE) in a medical-trauma-surgical ICU patients (7/2006-1/2008). Thromboprophylaxis was given routinely according to established evidence-based guidelines. First, a propensity score was derived from a multinomial logistic regression model to adjust for baseline imbalances. Then Cox proportional regression analysis was used to estimate hazard ratio adjusting for the generated propensity score. Results: Of the 798 patients in the cohort, 639 (80.0%) patients received a heparin for thromboprophylaxis: 174 patients received enoxaparin and 465 patients received UFH. There was no difference in VTE incidence during ICU stay in the two groups: 8.0% (3.1 per 1000 patient-days) for patients on enoxaparin and 7.5% (3.6 per 1000 patient-days) for those on UFH. Additionally, VTE incidence was 7.3% for patients on UFH 5000 units 12 hourly and 7.6% for those who received 5000 units 8 hourly (p=0.89). The VTE rates were similar in medical, trauma and surgical patients. Enoxaparin was associated with similar VTE risk compared with UFH (propensity score-adjusted hazard ratio, 0.95; 95% CI, 0.46-1.96). This finding was observed in medical, trauma and surgical patients. Conclusions: In a medical-trauma-surgical ICU, the use of enoxaparin was associated with similar VTE incidence and adjusted VTE risk compared with UFH. © 2018, American University of Beirut. All rights reserved.