Predictive Value of IL-6 and PDGF-AA for 28-Day Mortality Risk in Critical Ill Patients

Identification of prognostic biomarkers for critical illness are essential to improving mortality in the context of precision medicine. The purpose of this study was to evaluate the prognostic value of interleukin-6 (IL-6) and platelet-derived growth factor AA(PDGF-AA) in predicting 28-day mortality in critically ill patients.

199 critically ill patients were recruited from the emergency department of the Beijing Chaoyang Hospital, Capital Medical University, between October 2020 and April 2021. IL-6, PDGF-AA and other markers were tested immediately, and the Sequential Organ Failure Assessment (SOFA) and Acute Physiology and Chronic Health Evaluation II (APACHE II) scores were calculated within 24h of admission to the emergency department. Patients were divided into survival and non-survival groups according to clinical outcomes for 28 days. The quantitative detections of IL-6 and PDGF-AA were performed using the Luminex assay. Spearman correlation, logistic regression, and receiver operating characteristic curve (ROC) analyses were conducted for comparison.

Among 199 patients, 139 died and 60 survived within 28 days, IL-6 and PDGF-AA levels were higher in the non-survival group (P<0.05). IL-6 levels correlated with PDGF-AA levels in the non-survival group (P<0.001). IL-6 and PDGF-AA were independent predictors off 28-day mortality in critically ill patients (OR=1.003, 1.002). Combination of IL-6 and SOFA can make an AUROC of 0.892 with a specificity of 91.4%. Combination of IL-6, PDGF-AA and SOFA can make an AUROC of 0.905 with a specificity of 91.5%.

This study highlights the importance of monitoring serum levels of IL-6 and PDGF-AA in critically ill patients. Compared with the marker alone, combinations with other conventional risk factors have better predictive values.