Optimal Patient Selection for the Prophylactic Anticoagulation Therapy in Patients With Coronavirus Disease 2019.

To the Editor:

Coronavirus disease 2019 is associated with hypercoagulable states, but the prophylactic strategy including anticoagulation therapy remains unestablished. Santoro et al (1) demonstrated using a multicenter international prospective registry including over 5,000 hospitalized patients with coronavirus disease 2019 that anticoagulation therapy was not associated with better survival but rather with higher bleeding risk among the overall cohort. Instead, the survival benefit of anticoagulation therapy was found among those with respiratory failure requiring invasive ventilation. Several concerns have been raised.

The mechanism of why only the patients receiving invasive ventilation enjoyed better survival by anticoagulation therapy remains uncertain. It is uncertain whether the severity of coronavirus disease 2019, which is quantified by several biomarkers, or the severity of respiratory failure, which is quantified by blood gas data, is associated with the hypercoagulable status. It is of great interest to investigate whether these parameters stratify the efficacy of anticoagulation therapy.

The authors found that the patients requiring invasive ventilation were good candidates for anticoagulation therapy (1). Further surveillance to investigate any other optimal candidates of anticoagulation therapy would be helpful. In addition, many clinicians would like to know the impacts of each anticoagulation therapy including direct oral anticoagulant. Some patients with coronavirus disease 2019 might have antiplatelets at admission. It is of interest to know whether the add-on anticoagulation therapy would have survival benefit maintaining similar bleeding risk among those receiving antiplatelets.