Low-molecular-weight heparin for the prevention of clinical worsening in severe non-critically ill COVID-19 patients: a joint analysis of two randomized controlled trials

Coronavirus disease 2019 (COVID-19) carries a high risk of vascular thrombosis. However, whether a specific anticoagulation intensity strategy may prevent clinical worsening in severe COVID-19 patients is still debated. We conducted a joint analysis of two randomized controlled trials, COVID-19 HD (NCT044082359) and EMOS-COVID (NCT04646655), to assess the efficacy and safety of two anticoagulant regimens in hospitalized severe COVID-19 patients. Subjects with COVID-19-associated respiratory compromise and/or coagulopathy were randomly assigned to low (4000 IU qd) or high (70 IU Kg-1 every 12 h) enoxaparin dose. The primary efficacy endpoint was clinical worsening within 30 days, defined as the occurrence of at least one of the following events, whichever came first: in-hospital death, evidence of arterial or venous thromboembolism, acute myocardial infarction, need for either continuous positive airway pressure (CPAP) or non-invasive ventilation (NIV) in patients receiving standard oxygen therapy or none at randomization, and need for mechanical ventilation in any patient. The safety endpoint was major bleeding. We estimated the relative risk (RR) and its 95% confidence interval (CI) for the outcomes. Among 283 patients included in the study (144 in the low-dose and 139 in the high-dose group), 118 (41.7%) were on NIV or CPAP at randomization. 23/139 (16.5%) patients in the high-dose group reached the primary endpoint compared to 33/144 (22.9%) in the low-dose group (RR 0.72, 95% CI 0.45-1.17). No major bleeding was observed. No significant differences were found in the clinical worsening of hospitalized COVID-19 patients treated with high versus low doses of enoxaparin.