RT Journal Article SR Electronic T1 Selection of the Appropriate Control Group Is Essential in Evaluating the Cytokine Storm in COVID-19 JF In Vivo JO In Vivo FD International Institute of Anticancer Research SP 1295 OP 1298 DO 10.21873/invivo.12381 VO 35 IS 2 A1 VASSILIOU, ALICE G. A1 DIMOPOULOU, IOANNA A1 JAHAJ, EDISON A1 KESKINIDOU, CHRYSI A1 MASTORA, ZAFEIRIA A1 ORFANOS, STYLIANOS E. A1 KOTANIDOU, ANASTASIA YR 2021 UL http://iv.iiarjournals.org/content/35/2/1295.abstract AB Background/Aim: Lately, studies have reported contradicting results on the cytokine storm seen in critically-ill COVID-19 patients. Depending on the control group used, cytokines have been found to be higher, similar or even lower in COVID-19 compared to critical illnesses associated with elevated cytokine concentrations. However, most of these studies do not take into account critical illness severity. Hence, we decided to compare cytokine levels in critically-ill COVID-19 patients and critically-ill patients of a general intensive care unit (ICU), who did not have sepsis or septic shock, but had an equal disease severity. Patients and Methods: Interleukin (IL)-6, IL-8, IL-10 and tumour necrosis factor-α (TNF-α) were measured on ICU admission in mechanically ventilated, COVID-19 (N=36) and non-COVID-19 (N=30) patients, who had not received dexamethasone, and had equal critical illness severity. Non-COVID-19 patients did not have sepsis or septic shock. Results: In our case control study, circulating IL-6 and IL-10 were lower, while TNF-α and IL-8 levels were higher in critically-ill COVID-19 patients, compared to critically-ill non-COVID-19 patients. Conclusion: It is difficult to infer whether the cytokine storm seen in COVID-19 differs from other critical conditions. It is important to recognize that the conclusions of related studies may depend on control group selection.