Validation of the intensive care infection score for infection discrimination in burn patients compared with other inflammatory biomarkers (ICARUS study).

BACKGROUND: Distinguishing infection from non-infectious systemic inflammation remains a major challenge in critically ill burn patients. Conventional inflammatory biomarkers are frequently elevated following thermal injury, which may limit their diagnostic specificity. The Intensive Care Infection Score (ICIS) is a flow-cytometry-based composite biomarker that has not been systematically evaluated in burn patients. METHODS: In this prospective single-center observational study, adult burn ICU patients were included between June 2021 and August 2022. Infection status was determined retrospectively for each blood sample using a composite clinical reference standard incorporating microbiological findings, imaging when available, and documented antimicrobial treatment decisions, reflecting routine burn ICU practice. To avoid bias from repeated sampling, the primary analysis was performed at the patient level using one representative blood sample per patient. ICIS was compared with C-reactive protein (CRP), procalcitonin (PCT), white blood cell count (WBC), lipopolysaccharide-binding protein (LBP), presepsin, and calprotectin. Discriminatory performance was assessed using receiver operating characteristic (ROC) analysis. RESULTS: Sixty patients were included in the study. Infected patients demonstrated significantly higher ICIS values compared with non-infected patients. ICIS showed the highest discriminatory performance for infection, with an area under the ROC curve of 0.81 (95% CI 0.69-0.92), outperforming several conventional biomarkers. Patient-level comparisons confirmed greater separation between infected and non-infected patients for ICIS than for other evaluated biomarkers. CONCLUSIONS: In critically ill burn patients, ICIS demonstrated superior discrimination between infectious and non-infectious inflammatory states compared with several commonly used biomarkers when analyzed at the patient level. These findings support the potential role of ICIS as an adjunctive biomarker for infection evaluation in burn ICU patients. Further multicenter studies are warranted to validate these results and to define the clinical utility of ICIS, including its potential contribution to antimicrobial stewardship.