Serum interleukin-6 as a predictor of the severity of coronavirus disease 2019

Background Inflammatory markers like interleukin-6 (IL-6) are linked to the worse outcome in coronavirus disease 2019 (COVID-19) cases. Other markers such as C-reactive protein are not as reliable as IL-6 in predicting respiratory failure. Aim To assess the function of IL-6 as a predictor of COVID-19 severity. Patients and methods A total of 50 severe and critical patients with PCR-confirmed COVID-19 were included. All enrolled patients followed the case definition for confirmed cases of Egyptian national protocol for COVID-19 issued by MOHP. Clinical assessment, imaging, and laboratory data were recorded at admission. Pulmonary function was evaluated by SpO2/FiO2 ratio. Outcomes included hospital stay, prognosis of the disease, complications, death rate, and discharge, which were recorded during the follow-up. Results The elevated IL-6 group showed a significantly higher critical rate (87.1%) than the normal IL-6 group (26.3%) (P<0.0001), and the improvement rate was higher in the normal IL-6 group (73.7%). Moreover, the death rate was significantly greater in the elevated IL-6 group (38.7%) than the normal IL-6 group (10.5%) (P=0.033). The cutoff value of IL-6 levels in prediction of severity and mortality of COVID-19 was assessed. Our receiver operating characteristic results revealed that IL-6 cutoff value is higher than 50.27 for severity and the cutoff value is greater than 120.83 for mortality. The sensitivity values of IL-6 for severity and mortality were 93.3 and 90.5%, respectively, and the specificity values were 90.0 and 86.7%, respectively. Conclusion Elevated levels of serum IL-6 in COVID-19-infected patients were related with a variety of adverse outcomes, including severe illness, mechanical ventilation, and acute respiratory distress syndrome. When it came to accurately predicting the severity and mortality of COVID-19, the optimum IL-6 cutoff levels were 50.27 and 120.83 pg/ml, respectively.