Antiphospholipid Antibodies in Severe COVID-19: Frequency, Clinical Features, and 12-Week Follow-Up

BACKGROUND: Severe COVID-19 is characterized by a hypercoagulable state and elevated thrombotic risk, potentially linked to antiphospholipid antibodies (APLAs). The prevalence and clinical significance of APLAs in critically ill patients, particularly in low- and middle-income countries such as Bangladesh, remain unknown. METHODS: We conducted a prospective observational study among 100 adult patients admitted with severe COVID-19 to tertiary hospitals in Bangladesh between June 2021 and February 2022. We measured APLAs (IgM and IgG) and anticardiolipin antibodies (aCL; IgM and IgG) in serum samples obtained within 48 hours of admission. Patients with initially positive antibodies underwent follow-up testing at 12 weeks. We collected demographic, clinical, and laboratory data, along with thromboembolic events. Statistical analysis included paired t-tests and effect size estimation. RESULTS: Of the 100 patients prospectively enrolled, 57 were men, and the mean age was 60 (± 13.4) years. A total of 30 patients tested positive for at least one antibody at baseline. We observed a major decrease in APLA levels between baseline and week 12. Mean APLA IgM decreased from 13.95±10.53 to 5.12±6.60 (p=0.002) and APLA IgG levels from 18.8±37.42 to 5.64±5.22 (p=0.048). Similarly, aCL IgM declined from 16.68±9.75 to 5.49±6.73 (p