Attributable Mortality of Late‐Onset Sepsis in the Neonatal ICU According to Gestational Age: A Historical Propensity Score Matched Cohort Study

BACKGROUND: Late-onset sepsis is a major cause of morbidity and mortality in NICUs. This study reports the attributable mortality of late-onset sepsis across different gestational age groups. AIM: The objective of this study is to assess the attributable mortality of neonatal late-onset sepsis according to gestational age. STUDY DESIGN: A matched cohort study using a 10-year, single-centre historical cohort with propensity score matching to reduce confounders. Attributable mortality was determined in the total matched cohort and by gestational age: extremely preterm (< 28 weeks), very preterm (28-32 weeks + 6 days), late preterm (33-36 weeks +6 days) and full-term (≥ 37 weeks). RESULTS: The matched cohort included 4210 neonates. Attributable mortality of late-onset sepsis in the total cohort was 6.1% (95% CI, 4.7-7.8). It was highest in neonates born between 28 and 36 weeks: 7.1% (95% CI, 4.5-9.8) for very preterm, 8.1% (95% CI, 5.1-11.1) for late preterm and 2.8% (95% CI, 0.01-5.8) for term neonates. For extremely preterm newborns, it was 6.6% (95% CI, -1.1 to 14.5). CONCLUSIONS: Late-onset sepsis significantly impacts neonates, particularly those born between 28 and 36 weeks, even after adjusting for confounders. Larger-scale studies are needed to further understand the impact across gestational ages. Integrating gestational age into risk stratification tools may improve prevention, early detection and management of neonatal late-onset sepsis. RELEVANCE TO CLINICAL PRACTICE: Gestational age-specific risk profiles enable targeted monitoring and timely intervention for neonates at greatest risk of sepsis. Personalised care strengthens prevention and management, while nursing expertise in this context is vital for early detection and reducing mortality.