A BREAKTHROUGH study presented at ESCMID Global 2025 highlights IL-6 as a highly accurate early biomarker for sepsis in neonates, children, and pregnant women, three of the most vulnerable patient groups.
The retrospective cohort study evaluated IL-6’s diagnostic performance using serial blood samples from 252 patients with suspected sepsis, drawn from paediatric (n=111), maternity (n=72), and neonatal (n=69) populations. Patients were categorised by infection type (bacterial, viral, or no infection) and clinical response ranging from systemic inflammatory response syndrome to septic shock. The researchers compared IL-6 against conventional biomarkers like C-reactive protein (CRP) and procalcitonin (PCT), with diagnostic accuracy assessed via area under the receiver operating characteristic curve (AUROC).
IL-6 consistently outperformed CRP and PCT in identifying bacterial infections and stratifying sepsis severity. AUROC values reached 0.94 in pregnant patients, 0.91 in children, and 0.86 in neonates, all indicating strong diagnostic utility. Sensitivity and specificity both exceeded 80% in paediatric and maternity patients, with IL-6 detecting bacterial infections with 91% sensitivity in children and 94% in pregnant women. While neonatal sensitivity was lower at 67.6%, specificity remained high at 97.1%, likely reflecting the diagnostic complexity of neonatal sepsis. In contrast to CRP and PCT, which peak later, IL-6 rises within 1–2 hours and peaks at 6 hours, providing a valuable early window for clinical intervention.
The study reinforces IL-6’s value as a fast and reliable marker for sepsis detection and severity assessment, particularly in high-risk populations where early diagnosis is vital. With the availability of commercial assays and growing clinical familiarity following widespread use during the COVID-19 pandemic, IL-6 testing is increasingly feasible in real-world settings.
Reference
Whelan SO et al. Interleukin-6 as a diagnostic biomarker for sepsis in neonates, children and pregnant women – a real-world cohort study. ESCMID Global 2025, 11-15 April, 2025.
