Interleukin-6 and C-reactive Protein on Admission as Predictor of Mortality in Severe COVID-19 Patients: A Retrospective Cohort Study

Abstract

BACKGROUND: Predictors of mortality, an important factor to guide management in COVID-19 patients, have not been fully understood. Several inflammatory markers have been used to assess severity in COVID-19 patients in Indonesia. Few studies, however, have shown these markers as predictor of mortality. The common laboratory test for assessing severity in COVID-19 patients includes interleukin-6 (IL-6) and C-reactive protein (CRP). AIM: The aims of this study were determine the relationship between the two inflammatory biomarkers and mortality as well as their cutoff values in severe COVID-19 patients. METHODS: We retrospectively analyzed 80 confirmed patients with severe COVID-19 admitted to an intensive care unit of a secondary hospital in Indonesia between August and December 2020. They were analyzed for baseline clinical and laboratory findings at admission and during the disease. The primary outcome was mean level IL-6 and CRP of severe COVID-19 patients on admission. The secondary outcome was cutoff of IL-6 and CRP to predict mortality during the first 14 days of hospitalization. RESULTS: CRP and IL-6 levels were evaluated as prognostic factors for outcome using the ROC curve. A total of 80 confirmed patients consisting of 53 (71.25%) survivors and 23 (28.75%) non-survivors. Mortality was weakly correlated with levels of IL-6 (r = 0.249) and CRP (r = 0.247). The IL-6 cutoff was 101.64 pg/ml (AUROC 0.658 (95% CI 0.529 – 0.787); p = 0.028). The CRP cutoff was 46.45 mg/L (AUROC 0.659 (95% CI 0.532–0.786); p = 0.027). CONCLUSIONS: Levels of IL-6 and CRP at the first day of admission were weak predictors of mortality in severe COVID-19 patients.