Effectiveness and Safety of Enoxaparin Versus Unfractionated Heparin as Thromboprophylaxis in Hospitalized COVID-19 Patients: Real-World Evidence

Background: Coronavirus 2019 (COVID-19) patients are at risk of thrombosis. Literature that compares the effectiveness of enoxaparin to unfractionated heparin (UFH) in COVID-19 patients is scarce. Objective: We aimed to evaluate the effectiveness and safety of enoxaparin compared with UFH when used at their standard/intermediate dosing in COVID-19 patients. Methods: This was a retrospective study conducted at a large COVID-19 center located in Eastern Province, Saudi Arabia. Confirmed COVID-19 cases (≥18 years old) admitted between January and December 2020 were randomly screened for inclusion. Exclusion criteria were patients receiving therapeutic anticoagulation, on chronic anticoagulation, had active bleeding, a platelet count <25 × 10⁹/L, or an incomplete electronic file. The primary endpoint was the occurrence of any thrombotic event (pulmonary embolism, deep venous thrombosis, stroke, or myocardial infarction) or mortality. Secondary endpoints were major or minor bleeding. We applied inverse propensity score weighting (IPTW) with survival analysis to analyze the primary endpoint. Logistic regression was used for the secondary endpoint. Results: A total of 980 patients were included (enoxaparin, n = 470 and UFH, n = 510) with a mean age (±SD) of 47.7 (± 12.3) for the enoxaparin arm and 52 (±13.9) for the UFH arm. There was a statistically significant difference in the primary endpoint with an adjusted hazard ratio (aHR) of 0.46 (95%CI: 0.22 to 0.96, P = 0.039) in favor of the enoxaparin arm. There was no statistically significant difference in major or minor bleeding rates between the two arms. Conclusion and Relevance: When compared with UFH, enoxaparin was associated with a significant reduction in thrombotic events or mortality among COVID-19 patients. The results need confirmation from randomized controlled trials.