Prognostic value of interleukin-6 serum levels in hospitalized COVID-19 patients: A case-control study in Iran

The coronavirus pandemic (COVID-19) is an infectious disease with a high mortality rate that is challenging to treat. Cytokine storm is a crucial factor leading to acute respiratory distress syndrome in COVID-19 patients. Identifying factors that predict the severity of the disease may be primarily prognostic to guide drug therapy. The objective of this study was to investigate the prognostic role of interleukin 6 (IL-6) in the hospitalized patients infected with COVID-19.

This case-control study was conducted from October 2019 to April 2020 at Shahid Faqihi hospital in Iran. Fifty hospitalized COVID-19 patients and 50 healthy individuals were included while controlling demographics and comorbidities. IL-6 serum levels were measured and compared based on demographic characteristics (age, sex) and comorbidities in the case and control groups. Spearman rank correlation coefficient was also used to analyze the correlations between IL-6 levels and lung involvement in COVID-19 patients. Moreover, some laboratory parameters were compared based on the percentage of lung involvement.

The level of IL-6 in the case group was significantly higher than the control (p ˂ 0.001). We observed a positive and significant correlation between the level of IL-6 and the severity of lung involvement (r = 0.0.79, p < 0.01). The median level of IL-6 in patients who showed more than 75% lung involvement was 573 (IQR = 320-850).

Available evidence suggests that high levels of IL-6 are associated with the severity of COVID-19. According to the results, it could be proposed that inhibition of IL-6 might be a target for therapeutic managements to reduce mortality in the patients with COVID-19.