Interleukin-6 in COVID-19 Severity Stratification.

Background: The increase in the number of patients with COVID-19 on a global scale made the early recognition of severe forms of the disease essential. Considering that IL-6 acts as a pro-inflammatory mediator, mediating acute phase responses, the objective of this study was to assess its value in the early severity stratification of SARS-CoV2 infection. Materials and Methods: It was a prospective study included IL-6 measurement in patients with SARS-CoV2 infection upon admission to the emergency department. Two groups were considered (Group I: patients without hospitalization criteria; Group II: patients with hospitalization criteria). Analyzed variables were serum levels of IL-6, C-reactive protein, ferritin, d-dimers, sociodemographics, ventilator support, ICU admission, mortality, dates of diagnosis, hospitalization, and discharge. For the statistical analyses, Mann-Whitney test, Pearson's chi-square test, area under the receiver operating characteristic curve, Youden index, and Spearman correlation were applied. Results: A total number of 117 patients were included. Mean age was significantly higher for group II (72,35±15,39 years; p<0,001). No statistically significant difference was seen between the groups regarding gender (p=0,111). The IL-6 values showed an excellent power of discrimination for the need for hospitalization (AUC=0,888; p<0,001) and the need for ICU admission (AUC=0,897; p=7.9 × 10-5). Also, its cut-off value of 12,4pg/mL for the need for hospitalization and 42,95 pg/mL for the need for ICU admission was determined. Positive correlation was seen between IL-6 value and length of stay [r(35)=0,380; p=0,020]. Three deaths were observed among patients with hospitalization criteria (8,1%). Conclusion: The value of IL-6 at admission seems to independently influence the probability of hospitalization (general ward or ICU) and its duration.