Clinical Relevance of Antiphospholipid Antibodies Levels During the Course of Severe COVID-19

The aim of this study was to determine the clinical significance of antiphospholipid antibodies (APLs) during the follow-up of nine severe COVID-19 patients admitted to the Intensive Care Unit of the University Hospital. The measurement of APLs (IgG and IgM anti-cardiolipin (aCL) and anti-β2-glycoprotein-1 (aB2GP1) was performed on the 1st day and after 15 days of admission, using the chemiluminescence assay (threshold =19 CU). The average age of patients was 64.7 ± 20, 44 years (ranges: 30-88 years), with a sex-ratio of 1.25. On day-1, APLs were positive in two cases, the first of which was positive for IgG aβ2GP1 (94.9 CU) and IgG aCL (24.8 CU), and the second was positive only for IgG aβ2GP1 (31.4 CU). On day-15, APLs showed negative results for both aβ2GP1 and aCL for the first case, and decreasing titers of aβ2GP1 for the second one. Interestingly, these two cases showed no thromboembolic events and had a good clinical outcome. Conversely, APL positivity occurred at day-15 in two cases, corresponding to IgG aB2GPI (49.3 CU) in one case, and IgG aCL (76 CU) in the other. Both cases presented with a prolonged activated-partial-thromboplastin-time, high levels of D-dimers and fibrinogen, associated with increased levels of ferritin and interleukin-6. Our series has shown that IgG aB2GPI or IgG aCL can be either transient or appear secondarily with significantly high titers. The latter condition was associated with a poor clinical outcome, which emphasizes the importance of APLs monitoring in severe COVID-19 as a potential prognostic factor.