Assessment of inflammatory markers and their association with disease mortality in severe COVID-19 patients of tertiary care hospital in South India

Background: COVID-19 infection involves a complex interplay of the immunological and inflammatory responses. Low blood-oxygen levels have been a hallmark in COVID-19 patients. The lung tissue damage infiltered by the viral-mediated inflammation decreases oxygen saturation to cause silent hypoxia and cell death. This study aimed to evaluate the association of inflammatory biomarkers with oxygen saturation (SpO(2)) and mortality in severe COVID-19 patients. Methods: A total of 190 severe COVID-19 patients were included in this study after confirmed by the RT-PCR assay. The laboratory tests were performed for biochemical assessment. Serum levels of C-reactive protein (CRP), lactate dehydrogenase (LDH), and ferritin were determined and compared between survivors and nonsurvivors using independent sample t-test. The correlation of these inflammatory markers was studied using Spearman's correlation, and their association with mortality was studied using logistic regression. Results: All the COVID-19 patients were severe with SpO(2)< 90% and respiratory rate > 30/min. While the serum levels of CRP, LDH, ferritin, aspartate transaminase (AST), urea, and random blood sugar (RBS) were elevated, hemoglobin (Hb) and SpO(2) levels were reduced in COVID-19 patients. LDH and ferritin levels were significantly higher in nonsurvivors compared to survivors with p values of 0.001 and 0.022 respectively. Spearman's correlation showed a significant correlation of the inflammatory markers with SpO(2), serum electrolytes (potassium, chloride), liver enzymes (AST and alanine transaminase (ALT)), and markers of kidney damage (urea, creatinine). Conclusion: Inflammatory markers could effectively discriminate the risk of mortality in severe COVID-19 patients. As CRP, LDH, and ferritin levels determine the tissue oxygen availability, they seem to be valuable biomarkers in the prognosis of COVID-19.