Chronic anticoagulant treatment and risk of mortality in SARS-Cov2 patients: a large population-based study.

Background: Hypercoagulability is often seen in COVID-19 patients and thromboembolic events appear frequent; antithrombotic treatment has been proposed therefore as part of standard treatment for COVID-19. Under these premises, prior-to-infection antithrombotic treatment may have a protective effect with respect to COVID-19 related thromboembolic events. Aim of the present work was to evaluate the impact of prior-to-infection anticoagulant or antiplatelet treatment on COVID-19 outcomes.

Methods: Beneficiaries of the Regional Health Service of the Lombardy region of Italy aged ≥40 years with a COVID-19 diagnosis made between February 21^st and July 18^th, 2020 were included in the present study. The impact on COVID-19 mortality of pre-existing and chronic therapy with anticoagulant drugs (vitamin-K antagonist or new oral anticoagulants) was evaluated. Analyses were repeated with antiplatelets drugs.

Results: Among 79,934 SARS-CoV-2 patients beneficiaries of the Regional Healthcare System of the Lombardy Region who received a diagnosis between February 21^st and July 18^th, 2020, chronic pre-existing anticoagulant assumption was present in 6.0% and antiplatelets in 12.7%. The overall unadjusted mortality rate was 20.6%, with male sex, age category and comorbidity burden being significantly associated to increased mortality risk. Anticoagulant chronic treatment was not associated with a reduction in mortality. Similar results were observed when repeating the analyses for pre-existing oral antiplatelet treatment.

Conclusions: In a large population-based study evaluating more than 79,000 COVID-19 patients, pre-existing antithrombotic therapy was not associated to a benefit in terms of mortality. Further studies are needed to evaluate the role of antithrombotic therapy as standard treatment among COVID-19 patients.