PREDICTIVE IMMUNOLOGICAL, VIROLOGICAL, AND ROUTINE LABORATORY MARKERS FOR CRITICAL COVID-19 ON ADMISSION

ABSTRACT Introduction Early identification of COVID-19 patients at risk of critical illness is challenging for clinicians. Immunological, virological, and routine laboratory markers to be used in addition to clinical data are needed. Aim and methods Blood tests to measure neutrophil/lymphocyte ratio (NLR), levels of ferritin, CRP, D-dimer, complement components (C3, C4), lymphocyte subsets, and cytokines, and SARS-Cov2 RT-PCR tests were performed in COVID-19 confirmed cases within 48 hours of admission. Cycle threshold (Ct) values were determined by RT-PCR from oral or nasopharyngeal swabs on the day of admission. Severity of symptoms was categorized as mild (grade 1), severe (grade 2), and critical (grade 3). Results 120 patients were included. COVID-19 was mild in 49, severe in 32, and critical in 39. Ferritin >370 ng/mL (OR 16.4, 95% CI 5.3-50.8), D-dimer >440 ng/mL (OR 5.45, 95% CI 2.36-12.61), CRP >7.65 mg/dL (OR 11.54, 95% CI 4.3-30.8), NLR >3.77 (OR 13.4, 95% CI 4.3-41.1), IL-6 >142.5 pg/mL (OR 8.76, 95% CI 3.56-21.54), IL-10 >10.8 pg/mL (OR 16.45, 95% CI 5.32-50.81), sIL-2rα (sCD25) >804.5 pg/mL (OR 14.06, 95% CI 4.56-43.28), IL-1Ra >88.4 pg/mL (OR 4.54, 95% CI 2.03-10.17), and IL-18 >144 pg/mL (OR 17.85, 95% CI 6.54-48.78) were associated with critical COVID-19 in the univariate age-adjusted analysis. In the multivariate age-adjusted analysis, this association was confirmed only for ferritin, CRP,NLR, IL-10, sIL-2rα, and IL-18. T, B, and NK cells were significantly decreased in critical patients. SARS-CoV-2 was undetected in blood except in 3 patients with indeterminate results. Ct values determined by RT-PCR from oral/nasopharyngeal swabs on admission were not related to symptom severity. Conclusion levels of ferritin, D-dimer, CRP, NLR, and cytokines and cytokine receptors IL-6, IL1-Ra, sCD25, IL-18, and IL-10, taken together with clinical data, can contribute to the early identification of critical COVID-19 patients.