Background COVID‐19 is a respiratory disease associated to thrombotic outcomes with coagulation and endothelial disorders. Based on that, several anticoagulation (AC) guidelines have been proposed. We aimed to identify if AC therapy modifies the risk of developing severe COVID‐19. Methods and Results COVID‐19 patients initially admitted in medical wards of 24 French hospitals were included prospectively from February 26th to April 20th, 2020. We used Poisson regression model, Cox proportional hazard model and matched propensity score to assess the effect of AC on outcomes (intensive care unit (ICU) admission and/or in‐hospital mortality). Study enrolled 2878 COVID‐19 patients, among whom 382 (13.2%) were treated with oral AC therapy prior to hospitalization. After adjustment, AC therapy prior to hospitalization was associated with a better prognosis with an adjusted Hazard Ratio (aHR) 0.70 (95% CI 0.55‐0.88). Analyses performed using propensity score matching confirmed that AC therapy prior to hospitalization was associated with a better prognosis with an aHR of 0.43 (95% CI 0.29–0.63) for ICU admission and aHR of 0.76 (95% CI 0.61–0.98) for composite criteria ICU admission and/or death. In contrast, therapeutic or prophylactic low or high dose AC started during hospitalization were not associated with any of the outcomes. Conclusions AC therapy used prior to hospitalization in medical wards was associated with a better prognosis in contrast to AC initiated during hospitalization. AC therapy introduced in early step of disease could better prevent COVID‐19‐associated coagulopathy, endotheliopathy and prognosis.

Background: Coronavirus disease 2019 (COVID-19) has been associated with coagulation disorders, in particular high concentrations of D-dimers, and increased frequency of venous thromboembolism. Aim: To explore the association between D-dimers at admission and in-hospital mortality in patients hospitalized for COVID-19, with or without symptomatic venous thromboembolism. Methods: From 26 February to 20 April 2020, D-dimer concentration at admission and outcomes (in-hospital mortality or venous thromboembolism) of patients hospitalized for COVID-19 in medical wards were analysed retrospectively in a multicentre study in 24 French hospitals. Results: Among 2878 patients enrolled in the study, 1154 (40.1%) patients had D-dimer measurement at admission. Receiver operating characteristic curve analysis identified a D-dimer concentration > 1128 ng/mL as the optimum cut-off value for in-hospital mortality (area under the curve 64.9%, 95% confidence interval [CI] 0.60–0.69), with a sensitivity of 71.1% (95% CI 0.62–0.78) and a specificity of 55.6% (95% CI 0.52–0.58), which did not differ in the subgroup of patients with venous thromboembolism during hospitalization. Among 545 (47.2%) patients with D-dimer concentration > 1128 ng/mL at admission, 86 (15.8%) deaths occurred during hospitalization. After adjustment, in Cox proportional hazards and logistic regression models, D-dimer concentration > 1128 ng/mL at admission was also associated with a worse prognosis, with an odds ratio of 3.07 (95% CI 2.05–4.69; P < 0.001) and an adjusted hazard ratio of 2.11 (95% CI 1.31–3.4; P < 0.01). Conclusions: D-dimer concentration > 1128 ng/mL is a relevant predictive factor for in-hospital mortality in patients hospitalized for COVID-19 in a medical ward, regardless of the occurrence of venous thromboembolism during hospitalization.