Estimating the probability of bacterial infection using a novel biomarker among pediatric patients in the emergency department

Abstract

Context: IL-27 is a novel biomarker to identify bacterial infection in children.

Objective: IL-27 was evaluated among pediatric emergency department (ED) patients and compared with procalcitonin (PCT).

Methods and results: Children undergoing blood, urine, or cerebrospinal fluid cultures had IL-27 and PCT assays performed. Bacterial infection was defined as a positive culture or a clinical diagnosis based on chart review. IL-27 and PCT were increased among patients with bacterial infection and demonstrated comparable AUC's (0.62 versus 0.61). A decision tree incorporating IL-27, PCT, and white blood cell count improved the AUC (0.80).

Conclusion: IL-27 is a viable candidate biomarker to identify bacterial infection among ED patients and is comparable with PCT.

Keywords: IL-27; Interleukin-27; procalcitonin; sepsis.

Figure 1. CART Analysis for the Diagnosis of Bacterial Pneumonia (Secondary Analysis)

The CART-derived decision tree for estimating the probability of bacterial pneumonia, based on IL-27, PCT, and WBC count. Each node provides the total number of subjects in the node, the IL-27-, PCT-, or WBC-based decision rule, and the number of patients with and without bacterial pneumonia, with the respective probabilities. Terminal nodes (TN) 1 and 2 are low bacterial pneumonia probability nodes (probability 0.000 to 0.083). Terminal nodes 3 and 4 are intermediate bacterial pneumonia probability nodes (probability 0.294 to 0.325). Terminal node 5 is a high bacterial pneumonia probability node (probability 0.622). To calculate the diagnostic test characteristics, all subjects in the low probability terminal nodes (n = 86) were classified as predicted no bacterial pneumonia, whereas all subjects in the intermediate and high probability terminal nodes (n = 102) were classified as predicted bacterial pneumonia.

Figure 2. AUC for CART versus IL-27 or PCT Alone for Diagnosis of Bacterial Pneumonia (Secondary Analysis)

ROCs for the decision tree, IL-27 alone, and PCT alone for patients with bacterial pneumonia. The AUC for the decision tree was significantly greater than the AUCs for IL-27 alone and PCT alone (p < 0.05).