Antiphospholipid Antibodies in Critically Ill Patients With COVID‐19.

Objective: Coagulopathy is one of the characteristics observed in critically ill patients with coronavirus disease 2019 (COVID‐19). Antiphospholipid antibodies (aPLs) contribute to coagulopathy, though their role in COVID‐19 remains unclear. This study was undertaken to determine the prevalence and characteristics of aPLs in patients with COVID‐19. Methods: Sera collected from 66 COVID‐19 patients who were critically ill and 13 COVID‐19 patients who were not critically ill were tested by chemiluminescence immunoassay for anticardiolipin antibodies (aCLs), anti–β2‐glycoprotein I (anti‐β2GPI) (IgG, IgM, and IgA), and IgG anti‐β2GPI–domain 1 (anti‐β2GPI–D1) and IgM and IgG anti–phosphatidylserine/prothrombin (anti‐PS/PT) antibodies were detected in the serum by enzyme‐linked immunosorbent assay. Results: Of the 66 COVID‐19 patients in critical condition, aPLs were detected in 31 (47%). Antiphospholipid antibodies were not present among COVID‐19 patients who were not in critical condition. The IgA anti‐β2GPI antibody was the most commonly observed aPL in patients with COVID‐19 and was present in 28.8% (19 of 66) of the critically ill patients, followed by IgA aCLs (17 of 66, or 25.8%) and IgG anti‐β2GPI (12 of 66, or 18.2%). For multiple aPLs, IgA anti‐β2GPI + IgA aCLs was the most common antibody profile observed (15 of 66, or 22.7%), followed by IgA anti‐β2GPI + IgA aCL + IgG anti‐β2GPI (10 of 66, or 15.2%). Antiphospholipid antibodies emerge ~35–39 days after disease onset. A dynamic analysis of aPLs revealed 4 patterns based on the persistence or transient appearance of the aPLs. Patients with multiple aPLs had a significantly higher incidence of cerebral infarction compared to patients who were negative for aPLs (P = 0.023). Conclusion: Antiphospholipid antibodies were common in critically ill patients with COVID‐19. Repeated testing demonstrating medium to high titers of aPLs and the number of aPL types a patient is positive for may help in identifying patients who are at risk of developing cerebral infarction. Antiphospholipid antibodies may be transient and disappear within a few weeks, but in genetically predisposed patients, COVID‐19 may trigger the development of an autoimmune condition similar to the antiphospholipid syndrome (APS), referred to as "COVID‐19–induced APS‐like syndrome." Long‐term follow‐up of COVID‐19 patients who are positive for aPLs would be of great importance in understanding the pathogenesis of this novel coronavirus. [ABSTRACT FROM AUTHOR]