Purpose Aim of the study was to investigate whether aPL positivity correlated with thrombosis in COVID-19 patients and whether it was transient or persistent.
Methods We enrolled COVID-19 patients who underwent aPL tests: Lupus Anticoagulant (LA); IgM, IgG, IgA anticardiolipin antibodies (aCL); and IgM, IgG anti-β2-Glycoprotein-I antibodies (aβ2GPI).
Results Twenty-eight out of 73 (38.4%) patients resulted positive for at least one aPL assay: 32.8% for IgA aCL, 6.8% for IgM aCL and 4.1% for IgM aβ2GPI. No patients tested positive for IgG aPL or LA at the first determination. Seven (9.6%) patients developed thrombotic events during hospitalization, with 4 of them resulting positive for aPL. In patients with thrombotic events during hospitalization the risk of death was increased 9-fold (LR+8.9, p=0.003). Patients with double positivity for aCL and aβ2GPI IgM had a LR+ of 6.3 to have thrombotic events (p=0.012) and a LR+ of 4.9 to have elevated D-dimer levels (p=0.027). In 10 out of 28 positive patients, aPL was detected in a second occasion at least 12-weeks apart and two patients confirmed the positivity.
Conclusion Results suggest that double positivity for aCL and aβ2GPI IgM increases the risk of thrombosis in COVID-19, unlike IgA aCL positivity. APL positivity may be persistent, and it is advisable to monitor it over time.