Frequency and clinical correlates of antiphospholipid antibodies arising in patients with SARS-CoV-2 infection: findings from a multicentre study on 122 cases

COVID-19 features include disseminated intravascular coagulation and thrombotic microangiopathy indicating a hypercoagulable state. We aimed to investigate antiphospholipid antibodies (aPL) prevalence and clinical relationships in a large cohort of COVID-19 patients. We analysed the prevalence and titres of serum aPL in 122 patients with COVID-19 and 157 with primary antiphospholipid syndrome (PAPS) and 91 with other autoimmune rheumatic diseases (oARD) for comparison. IgG/IgM anticardiolipin (aCL) and IgG/IgM anti-beta2glycoprotein I (β2GPI) were assayed using homemade ELISA, IgA aCL and anti-β2GPI by commercial ELISA kits and lupus anticoagulant (LAC) by multiple coagulation tests following updated international guidelines. Prevalence of IgG and IgM aCL and of IgG and IgM anti-β2GPI across COVID-19 patients were 13.4%, 2.7%, 6.3% and 7.1%, being significantly lower than in PAPS (p