Association between serum inflammatory parameters and the disease severity in COVID-19 patients

Most patients infected with the novel coronavirus (SARS-CoV-2), as the causative agent of COVID-19 disease, show mild symptoms, but some of them develop severe illness. The purpose of this study was to analyze the blood markers of COVID-19 patients and to investigate the correlation between serum inflammatory cytokines and the disease severity.

In this prospective cross-sectional study, 50 patients with COVID-19 and 20 patients without COVID-19 were enrolled. According to ICU admission criteria, patients were divided into two groups of non-severe and severe. Differences in the serum levels of C-reactive protein (CRP), IL-6, and TNF-α, as well as erythrocyte sedimentation rate (ESR), lymphocytes (LYM) count, and neutrophils (NEU) count between the two groups were determined and analyzed.

Out of the 50 patients with COVID-19, 14 were diagnosed as severe cases. There was no significant difference between the two groups of COVID-19 patients in terms of gender and age. Blood tests of COVID-19 patients showed a significant decrease and increase in NEU and LYM counts, respectively. There were significant differences in the serum levels of IL-6, TNF-α, and CRP between the severe and non-severe groups, which were higher in the severe group. Also, there was a significant correlation between the disease severity and CRP with ESR (r = 0.79), CRP with IL-6 (r = 0.74), LYM with NEU (r = -0.97), and ESR with TNF-α (r = 0.7).

The findings of this study, as the first study in Iran, suggest that the levels of IL-6, TNF-α, ESR, and CRP could be used to predict the severity of COVID-19 disease.