Antiphospholipid Antibodies and Vascular Thrombosis in Patients with Severe Forms of COVID-19.

Antiphospholipid antibodies (aPLA) are a laboratory criterion for the classification of antiphospholipid syndrome (APS) and are known to cause clinical symptoms such as vascular thrombosis or obstetric complications. It is suggested that aPLA may be associated with thromboembolism in severe COVID-19 cases. Therefore, we aimed to combine clinical data with laboratory findings of aPLA at four time points (admission, worsening, discharge, and 3-month follow-up) in patients hospitalized with COVID-19 pneumonia. In 111 patients with COVID-19 pneumonia, current and past history of thrombosis and pregnancy complications were recorded. Nine types of aPLA were determined at four time points: anticardiolipin (aCL), anti-β2-glycoprotein I (anti- β2GPI), and antiphosphatidylserine/prothrombin (aPS/PT) of the IgM, IgG, or IgA isotypes. During hospitalization, seven patients died, three of them due to pulmonary artery thromboembolism (none were aPLA positive). Only one of the five who developed pulmonary artery thrombosis was aPLA positive. Out of 9/101 patients with a history of thrombosis, five had arterial thrombosis and none were aPLA positive at admission and follow-up; four had venous thrombosis, and one was aPLA positive at all time points (newly diagnosed APS). Of these 9/101 patients, 55.6% were transiently aPLA positive at discharge only, compared to 26.1% without a history of thrombosis (