A HOSPITAL BASED STUDY OF INTERLEUKIN-6 (IL-6) IN COVID-19 POSITIVE PATIENTS IN CORRELATION WITH OTHER BIOCHEMICAL MARKERS AND DISEASE SEVERITY IN NORTH-EAST INDIA

Introduction: Interleukin-6 (IL- 6) is a pleiotropic cytokine released by a variety of cell types such as immune cells and even certain tumour cells. The present study was undertaken to determine the levels of interleukin-6 (IL-6) and evaluate its association with clinical presentation, severity, radiological imaging, management, comparison with other biomarkers (CRP/D-Dimer / Ferritin/ LDH –both baseline and trend in COVID-19 patients. Methods: A retrospective cross-sectional follow up study was conducted on 109 Covid-19 positive adult patients admitted in our institute recruited following set inclusion and exclusion criteria. Demographic, Laboratory and Clinical data were collected from these patients namely fiO2, platelet count, presence of hypotension, neurological status via Glasgow coma Scale [GCS], serum bilirubin and serum creatinine. These data were used to calculate the Sequential Organ Failure Assessment (SOFA) score, ranging from 0-24. Serum interleukin 6 [IL-6], the chief biomarker under study was estimated along with other biomarkers known to be elevated in COVID-19, namely, serum high sensitive Troponin-I [hs-Trop-I], D-dimer, Ferritin, Lactate dehydrogenase [LDH], C-reactive protein [CRP], Procalcitonin [PCT] and total leucocyte count [TLC], using standardized manufacturer approved methods, in fully automated analyzers; Cobas 601 immunoassay system [Roche], Dimension EXL 200 Clinical Chemistry analyzer [Siemens] and Vidas PC [BioMérieux]. The data generated was analyzed by GraphPad Prism (v.8.0), considering a P value of ≤ 0.05 to be statistically significant. Out of the 109 patients with COVID-19, recruited in Results: to the study, a significant proportion showed positive association between serum IL-6 levels and serum levels of hs-Trop-I [p=0.0018], D-Dimer [p<0.0001], ferritin [p<0.0001], LDH [p<0.0001], PCT [p<0.0001] and TLC [p<0.0001]. A positive and significant correlation was observed between SOFA score and serum levels of IL-6 [Spearman r=0.2955, p=0.0018], D-Dimer [Spearman r=0.2321, p=0.0152], ferritin [Spearman r=0.2389, p=0.0124] and PCT [Spearman r=0.2194, p=0.0219]. Serum IL-6 is a suitable biomarker that correlates well with disease severity Conclusions: as assessed by the SOFA score. Moreover, serum IL-6 in conjunction with other biochemical markers of inflammation, cardiac ischemia and sepsis can act as an effective panel in aiding diagnosis as well as predicting outcome in COVID-19 infection.