Anticoagulation prior to hospitalization is a potential protective factor for COVID-19: insight from a French multicenter cohort study.

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.