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Level of IL-6 predicts respiratory failure in hospitalized symptomatic COVID-19 patients

Our take —

Concentrations of IL-6, a biomarker of inflammation, were strongly associated with respiratory failure in a small group of COVID-19 patients without accounting for possible confounding factors. Further studies of this potential association between IL-6 and respiratory failure or other clinical outcomes are warranted.

Study design

Case Series

Study population and setting

All patients (n=40) with lab-confirmed, symptomatic SARS-CoV-2 infection at University Hospital, Munich, Germany, from February 29, 2020 to March 27, 2020 were included. Various baseline clinical and laboratory measurements were assessed for associations with the clinical outcome of respiratory failure (i.e. requiring mechanical ventilation, n=13). Length of follow-up was not indicated.

Summary of Main Findings

Markers of inflammation, pulse rate, creatinine, and lactate dehydrogenase levels were associated with subsequent respiratory failure. IL-6 concentrations showed a particularly strong association with respiratory failure (p < 0.001 from Wilcoxon rank sum test), as 12/13 patients with respiratory failure, and 1/27 patients without respiratory failure, had IL-6 concentrations > 80 pg/mL.

Study Strengths

Authors appropriately adjusted analyses for multiple comparisons using the Bonferroni correction. Multiple comparisons are problematic because the more associates are looked for, the more potentially erroneous associations can be found.

Limitations

The sample size was small. Baseline determinants of IL-6 concentrations other than COVID-19 were not considered. Analyses do not account for potentially confounding factors (i.e. all analyses are bivariate).

Value added

This study provides modest evidence that IL-6 concentrations may have prognostic value for clinical outcomes such as respiratory failure.