Supplementary Material for: sCD126 as An Independent Prognostic Biomarker in Critical COVID-19

Introduction: Biomarkers to predict response of critical COVID-19 to tocilizumab (TCZ) are under investigation. Serum levels of interleukin (IL)-6 and IL-6 soluble receptors were studied in a cohort of patients all receiving treatment with TCZ. Methods: In this prospective clinical study, IL-6, soluble (s) CD126 and sgp130 were measured in the serum of 127 patients with critical COVID-19 the first 24 hours from start of mechanical ventilation and before start of TCZ treatment. Outcome was expressed as the World Health Organization Clinical Progression Scale (WHO-CPS) by day 28. The primary endpoint was the identification of a cut-off of the biomarkers which can predict WHO-CPS 6 or more by day 28.Results: Stepwise regression analysis with WHO-CPS ≥6 as the outcome and comorbidities, baseline oxygenation and baseline markers of severity showed that sCD126 ≥100ng/ml is independently associated with worse outcome (Odds ratio 2.42; 95% confidence intervals 1.05 to 5.63; p: 0.039). Conclusion: In a cohort of patients with critical COVID-19 receiving TCZ, sCD126 was a predictor of 28-day outcome.