Treatment with prophylactic oral anticoagulants and the risk of mortality in COVID-19 patients: a nationwide cohort study.

Background: Venous thromboembolism has been reported in patients with coronavirus disease 2019 (COVID-19). It remains unclear if premorbid use of prophylactic oral anticoagulation, for reasons other than COVID-19, protects against death in patients with COVID-19. The aim of this study was to estimate if the risk of all-cause mortality, hospital admission or intensive care unit (ICU) admission for individuals with verified SARS-CoV-2 was lower if patients used oral anticoagulant (OAC) therapy prior to a positive COVID-19 status. Methods: Data were obtained using national health registries. Cohort entry was the day of a positive SARS-CoV-2 test, and individuals were followed for 14 days or until death or hospital admission. Adjusted Cox proportional hazard regressions and competing risk analyses were used to estimate the risk of all-cause mortality, hospital admission and ICU admission in OAC users compared with patients with no use of OAC. Results: In this nationwide cohort study a total of 244 522 individuals were included (median age 35 years (interquartile range 21-52); 124 095 (51%) female), among whom 3710 (1.5%) were OAC users. In the adjusted Cox regression cohort, there was no difference in risk of all-cause mortality in OAC versus non-OAC users. (hazard ratio (HR) 1.13, 95% CI 0.99-1.30). Hospital admission risk (HR 1.11, 95% CI 1.02-1.20) was slightly increased in OAC users, and there was no difference between the groups regarding the risk of ICU admission (HR 0.96, 95% CI 0.74-1.24). Conclusions: In individuals with confirmed SARS-CoV-2, pre-existing treatment with OAC was not associated with prophylactic benefits in the prevention of hospital admission, ICU admissions or death. Prescription patterns should remain unchanged.