Abstract

Background: The COVID-19 pandemic has significantly impacted healthcare systems worldwide, particularly in intensive care units (ICUs) where mortality remains high. Biomarkers such as interleukin-6 (IL-6), C-reactive protein (CRP), procalcitonin (PCT), and D-dimer have been explored as predictors of disease severity and mortality in critically ill COVID-19 patients. Methods: This retrospective cohort study evaluated 325 COVID-19 ICU patients at IBN Sina Diagnostic Imaging Center, Dhaka, from September 2020 to December 2021. Serum levels of IL-6, CRP, PCT, and D-dimer were measured upon ICU admission. Mortality outcomes were recorded, and logistic regression models were used to assess the relationship between elevated biomarker levels and mortality. The predictive value of each biomarker was evaluated using receiver operating characteristic (ROC) curves. Results: Elevated IL-6 (≥30 pg/mL), CRP (≥100 mg/L), PCT (≥0.5 ng/mL), and D-dimer (≥1 µg/mL) were significantly associated with higher mortality (p<0.05). The cumulative mortality rate was 45.2%, with IL-6, CRP, PCT, and D-dimer showing odds ratios of 2.8, 2.1, and 3.2, respectively, for mortality risk. The combination of all four biomarkers  yielded an area under the curve (AUC) of 0.87, indicating high predictive accuracy. Conclusion: IL-6, CRP, PCT, and D-dimer levels serve as important prognostic markers for mortality in critically ill COVID-19 patients. The combination of these biomarkers improves predictive accuracy, helping guide clinical decisions and optimize patient care in ICU settings.

Keywords: IL-6, CRP, PCT, D-dimer, COVID-19, mortality prediction, ICU