Authors’ reply
We read with great interest the article by Szarpak et al1 showing the association between high blood levels of cytokines and the severity of coronavirus disease 2019 (COVID-19). In order to confirm the effect of cytokines, including interleukin 6 (IL-6), as predictors of COVID-19 severity, they performed a meta-analysis. Pooled analysis showed significantly higher IL-6 levels for patients with severe conditions compared with the nonsevere group, and also for patients who died from COVID-19 compared with those who survived. These results are in agreement with our hypothesis and with other studies suggesting the major role of IL-6 in the pathogenesis of COVID-19–induced cytokine storm.2,3 Moreover, the significantly increased levels of IL-6 in patients with COVID-19 have been considered an independent biomarker for predicting a poor prognosis.3 However, the levels of inflammatory cytokines in patients with a severe course of COVID-19 are significantly less elevated than in patients with acute respiratory distress syndrome unrelated to COVID-19 or sepsis.4
On the other hand, other studies revealed a positive correlation of coagulopathy with cytokine storm in patients with COVID-19. Namely, D-dimer concentration rises early, which indicates that coagulopathy acts as a prodrome of the cytokine storm.5
In conclusion, current data suggest that elevated blood levels of IL-6, C-reactive protein, and D-dimer, as well as lymphopenia are the best predictors of the fatal outcome of COVID-19.4,5
Janusz Marcinkiewicz, Grzegorz Majka (Department of Immunology, Faculty of Medicine, Jagiellonian University Medical College, Kraków, Poland)
This work was supported by the study conducted during the research project financed by the National Science Centre, Poland (project no. 2017/27/B/NZ6/001772; to JM).
None declared.
Marcinkiewicz J, Majka G. Cytokines as predictors of COVID-19 severity: evidence from a meta-analysis. Authors’ reply. Pol Arch Intern Med. 2021; 131: 100. doi:10.20452/pamw.15794
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