Evaluation of the Diagnostic Efficacy of IL-6 as an Early Marker of Neonatal Sepsis

Background: Neonatal sepsis is a leading cause of morbidity and mortality in newborns. Early diagnosis is challenging due to nonspecific clinical signs, and conventional markers such as blood culture and C-reactive protein have limitations. Interleukin-6 (IL-6) is a pro-inflammatory cytokine that rises early in response to infection and may serve as a useful diagnostic biomarker. Objectives: To evaluate the diagnostic efficacy of serum IL-6 as an early marker of neonatal sepsis and its association with disease severity and mortality. Materials and Methods: This retrospective study was conducted in the Neonatal Intensive Care Unit of Indira Gandhi Institute of Medical Sciences, Patna, Bihar, over 24 months. Medical records of 100 neonates evaluated for suspected sepsis were reviewed. Serum IL-6 levels were measured at the time of initial sepsis evaluation. Diagnostic performance of IL-6 was assessed using sensitivity, specificity, positive and negative predictive values, and receiver operating characteristic (ROC) curve analysis. Associations between IL-6 levels, type of sepsis, and outcomes were also analyzed. Results: Among the 100 neonates, 62% were male and 56% were preterm. Serum IL-6 levels were significantly elevated in septic neonates compared to non-septic neonates (p < 0.001). At a cutoff of ≥80 pg/mL, IL-6 demonstrated sensitivity 91.7%, specificity 85.7%, and AUC 0.93. Non-survivors had significantly higher IL-6 levels than survivors (212.8 ± 44.9 pg/mL vs 144.2 ± 36.5 pg/mL, p < 0.001). Late-onset sepsis was associated with higher IL-6 levels than early-onset sepsis (181.9 ± 49.6 pg/mL vs 148.6 ± 40.2 pg/mL, p = 0.003). Conclusion: Serum IL-6 is a highly sensitive and specific early biomarker for neonatal sepsis. Elevated IL-6 levels are associated with disease severity, late-onset sepsis, and increased mortality. Incorporating IL-6 measurement in early sepsis evaluation may facilitate prompt diagnosis, risk stratification, and improved neonatal outcomes.