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

Clin Exp Rheumatol. Jul-Aug 2020;38(4):754-759. Epub 2020 Jul 28.


Objectives: 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.

Methods: 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.

Results: 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<0.0001 for all). Frequency of IgG aCL and IgM anti-β2GPI was comparable to oARD (13.4% vs. 13.2% and 7.1% vs. 11%, respectively), while IgG anti-β2GPI and IgM aCL were lower (p<0.01). IgA aCL and IgA anti-β2GPI were retrieved in 1.7% and 3.3% of COVID-19 patients, respectively. Positive LAC was observed in 22.2% COVID-19 vs. 54.1% of PAPS (p<0.0001) and 14.6% of oARD (p=0.21). Venous or arterial thromboses occurred in 18/46 (39.1%) COVID-19 patients and were not associated with positive aPL (p=0.09).

Conclusions: Thrombosis is a frequent manifestation during COVID-19 infection. However, prevalence and titres of aPL antibodies or LAC were neither consistently increased nor associated with thrombosis when measured at a single timepoint, therefore not representing a suitable screening tool in the acute stage of disease.

Publication types

  • Multicenter Study

MeSH terms

  • Antibodies, Anticardiolipin / blood
  • Antibodies, Antiphospholipid / blood*
  • Antiphospholipid Syndrome / blood
  • Betacoronavirus
  • COVID-19
  • Coronavirus Infections / blood
  • Coronavirus Infections / immunology*
  • Humans
  • Immunoglobulin G / blood
  • Immunoglobulin M / blood
  • Pandemics
  • Pneumonia, Viral / blood
  • Pneumonia, Viral / immunology*
  • SARS-CoV-2
  • Thrombosis / complications
  • Thrombosis / virology
  • beta 2-Glycoprotein I / immunology


  • Antibodies, Anticardiolipin
  • Antibodies, Antiphospholipid
  • Immunoglobulin G
  • Immunoglobulin M
  • beta 2-Glycoprotein I