Intermediate- vs. Standard-Dose Prophylactic Anticoagulation in Patients With COVID-19 Admitted in Medical Ward: A Propensity Score-Matched Cohort Study

Background: Microthrombosis and large-vessel thrombosis are the main triggers of COVID-19 worsening. The optimal anticoagulant regimen in COVID-19 patients hospitalized in medical wards remains unknown. Objectives: To evaluate the effects of intermediate-dose vs. standard-dose prophylactic anticoagulation (AC) among patients with COVID-19 hospitalized in medical wards. Methods and results: We used a large French multicentric retrospective study enrolling 2,878 COVID-19 patients hospitalized in medical wards. After exclusion of patients who had an AC treatment before hospitalization, we generated a propensity-score-matched cohort of patients who were treated with intermediate-dose or standard-dose prophylactic AC between February 26 and April 20, 2020 (intermediate-dose, n = 261; standard-dose prophylactic anticoagulation, n = 763). The primary outcome of the study was in-hospital mortality; this occurred in 23 of 261 (8.8%) patients in the intermediate-dose group and 74 of 783 (9.4%) patients in the standard-dose prophylactic AC group ( p = 0.85); while time to death was also the same in both the treatment groups (11.5 and 11.6 days, respectively, p = 0.17). We did not observe any difference regarding venous and arterial thrombotic events between the intermediate dose and standard dose, respectively (venous thrombotic events: 2.3 vs. 2.4%, p=0.99; arterial thrombotic events: 2.7 vs. 1.2%, p = 0.25). The 30-day Kaplan–Meier curves for in-hospital mortality demonstrate no statistically significant difference in in-hospital mortality (HR: 0.99 (0.63–1.60); p = 0.99). Moreover, we found that no particular subgroup was associated with a significant reduction in in-hospital mortality. Conclusion: Among COVID-19 patients hospitalized in medical wards, intermediate-dose prophylactic AC compared with standard-dose prophylactic AC did not result in a significant difference in in-hospital mortality.