Association Between Serum IL-6 Levels and Disease Severity Among COVID-19 Patients Hospitalized at a Tertiary Care Hospital in Bangladesh.

Introduction COVID-19 severity varies widely among patients, and early identification of those at risk for severe disease is essential. IL-6, a key inflammatory cytokine, has been implicated in the pathogenesis of severe COVID-19. This study aimed to assess the association between serum IL-6 levels and disease severity among hospitalized COVID-19 patients at Bangabandhu Sheikh Mujib Medical University (BSMMU). Methodology A cross-sectional study was conducted among 90 RT-PCR-confirmed COVID-19 patients admitted to BSMMU. Patients were categorized into non-severe, severe, and critical groups based on WHO guidelines. Serum IL-6 levels and routine laboratory parameters were measured. Statistical analyses included chi-square tests, correlation analysis, logistic regression, and ROC curve evaluation to determine predictors of severity. Results Higher IL-6 levels were significantly associated with increasing disease severity. Severe and critical patients were older and more likely to have diabetes or hypertension. IL-6 showed positive correlations with neutrophil count, CRP, ferritin, D-dimer, and lactate dehydrogenase (LDH), and a negative correlation with lymphocyte count. Logistic regression identified IL-6 >14 pg/mL as an independent predictor of severe or critical disease. Receiver operating characteristic (ROC) analysis demonstrated excellent diagnostic performance of IL-6 in predicting severe outcomes. Conclusion Elevated IL-6 levels correlate strongly with COVID-19 severity and independently predict severe or critical illness. IL-6 may serve as an effective biomarker for early risk stratification, enabling timely intervention and improved patient management. Further studies are recommended to validate these findings and explore IL-6-targeted therapies.