Aims: To estimate if chronic anticoagulant (CAC) treatment is associated with morbidity and mortality outcomes of patients hospitalized for SARS-CoV-2 infection. Methods: In this European multicentric cohort study, we included 1186 patients of whom 144 were on CAC (12.1%) with positive coronavirus disease 2019 testing between 1 February and 30 July 2020. The average treatment effect (ATE) analysis with a propensity score-matching (PSM) algorithm was used to estimate the impact of CAC on the primary outcomes defined as in-hospital death, major and minor bleeding events, cardiovascular complications (CCI), and acute kidney injury (AKI). We also investigated if different dosages of in-hospital heparin were associated with in-hospital survival. Results: In unadjusted populations, primary outcomes were significantly higher among CAC patients compared with non-CAC patients: all-cause death (35% vs. 18% P\u200a<\u200a0.001), major and minor bleeding (14% vs. 8% P\u200a=\u200a0.026; 25% vs. 17% P\u200a=\u200a0.014), CCI (27% vs. 14% P\u200a<\u200a0.001), and AKI (42% vs. 19% P\u200a<\u200a0.001). In ATE analysis with PSM, there was no significant association between CAC and primary outcomes except for an increased incidence of AKI (ATE +10.2%, 95% confidence interval 0.3-20.1%, P\u200a=\u200a0.044). Conversely, in-hospital heparin, regardless of dose, was associated with a significantly higher survival compared with no anticoagulation. Conclusions: The use of CAC was not associated with the primary outcomes except for the increase in AKI. However, in the adjusted survival analysis, any dose of in-hospital anticoagulation was associated with significantly higher survival compared with no anticoagulation
