Risks associated with prior oral anticoagulation use in hospitalized COVID-19 patients – A retrospective cohort study on 5392 patients from a tertiary centre

There are conflicting data on prior oral-anticoagulant (OAC) use and outcomes of hospitalized COVID-19 patients. Due to uncertainties regarding associated risks with the prior OAC use, we have investigated this issue in a large cohort of hospitalized COVID-19 patients from our institution. We have retrospectively evaluated a total of 5392 consecutive COVID-19 patients hospitalized in our tertiary center institution in period 3/2020 to 6/2021. Majority of patients received low-molecular-weight-heparin thromboprophylaxis and corticosteroids during hospitalization. Patients' characteristics and clinical outcomes were documented as a part of a hospital registry project and were evaluated according to the prior non-OAC, warfarin and direct oral anticoagulants (DOAC) use. Median age was 72 years, median Charlson comorbidity index (CCI) was 4 points. There were 56.2% male patients. Majority of patients had severe (70.5%) or critical (15.8%) COVID-19 on admission. A total of 84.8% patients did not receive prior OAC, 9% were previously anticoagulated with warfarin and 6.2% were previously anticoagulated with DOACs. In the multivariate regression analyses, prior warfarin use was associated increased in-hospital mortality (OR 1.24, P = 0.048) independently of older age (OR 2.12, P