Interleukin-6 and Ferritin as Prognosticators in SARS-CoV-2 Patients from Kashmir, North India

Background: Identifying early predictive biomarkers of disease severity and disease outcome is fundamental for the practical management of Covid -19 patients. Although prognostic value of several Pro- and inflammatory markers have been determined in different population studies, however, it remained to be determined in SARS-CoV-2 patients from Kashmir.

Aim: To evaluate the predictive value of ferritin and IL-6 levels in RT- PCR confirmed SARS-CoV-2 patients from Kashmir.

Study Design: A Cohort Study.

Place and Duration of Study: The study was done at Government Medical College, Srinagar Kashmir, North India between October 2020 to November 2021.

Method: Here, we estimated ferritin and IL-6 levels respectively by chemiluminescent method on fully automated immune analyzer and by ELISA in a cohort of 100 RT-PCR confirmed SARS-CoV-2 patients, which were followed twice (14th and 28th day) for a period of one month.

Results: Based on estimated ferritin levels, the cohort was categorized into Mild = <500 ng/ml, Moderate = ≥500-<1500, and High = ≥1500ng/ml. Also patients were grouped as Mild = 0-<10pg/ml, Moderate = ≥10-<80pg/ml and High =≥80pg/ml based on Interleukin IL-6 levels. Correlation analysis of SARS-CoV-2 patients of varying ferritin levels with disease severity revealed a percent increase in the number of patients of stage 3 severity as ferritin levels increased from mild, to moderate and high levels. Similarly, a percent increase in the number of SARS-CoV-2 patients of increased severity was found as IL-6 levels increased from mild to moderate and high levels. Further, the ROC analysis of ferritin and IL-6 levels with disease outcome suggested both ferritin and IL-6 as early predictive markers of poor disease outcome. However, IL-6, with AUC =0.70 and sensitivity of 70% and specificity of 62%, is a better early predictive marker of poor disease outcome than ferritin with AUC=0.66 at sensitivity of 60% and specificity of 68% in SARS-CoV-2 patients from Kashmir. Further ROC analysis of patients with very high ferritin levels (>1500ng/ml) alone suggests it as an early predictive marker of patients with hyperinflammatory phenotype.

Conclusion: Estimation of ferritin and IL-6 levels as simple complementary early prognostic markers that are helpful in clinical decision-making and selecting appropriate treatment options in SARS-CoV-2 patients from Kashmir, North India.