Interleukin-6 versus ferritin and D-Dimer in the cytokine release syndrome in critically ill Covid-19 patients

ABSTRACT

Introduction: The lack of a clear definition of cytokine release syndrome (CRS) allowed this study to analyze the utility of interleukin-6 (IL-6), ferritin, and D-dimer (DD) with other variables and their clinical evolution. Methods: A prospective, observational, and analytical study was conducted from October 2020 to July 2021 in 125 patients in the intensive care unit (ICU) of Hospital Obrero Nro. 2 of the Caja Nacional de Salud in Cochabamba, Bolivia. The three markers and other exams were requested to determine correlations, survival, and relationship with CRS. Results: The mean ferritin was 1193.7±814.8 ng/ml, D-dimer 1427±1005 ng/ml, and IL-6 58.5±34.1 pg/mL. No statistical association was found between these markers, but a Spearman's Rho of 0.5 between ferritin and DD (p<0.05) was found in patients who died. In addition, there were associations between male gender and ferritin, DD and dyspnea, and IL-6 and tracheostomy. Survival was 9 days 95% CI (8.02-9.98) with similar values of DD and ferritin for both normal and elevated levels. The values of the area under the curve (AUC) did not show prediction of mortality, but a rate of 70%. Survival was better in those who did not suffer from acute respiratory distress syndrome (ARDS), with eight days (p=0.011). Conclusions: It is not possible to relate CRS to IL-6, DD, and ferritin, or to define it with fever, leukocytosis, renal failure, tracheostomy, due to the heterogeneous values of IL-6 in relation to COVID-19 and other inflammatory pathologies. The position of a hypoinflammatory disease rather than a hypercytokinemia remains in doubt. © 2022 The authors.