Stool biomarkers discriminate confirmed necrotizing enterocolitis in preterm infants

BACKGROUND: Necrotizing enterocolitis (NEC) is a major cause of morbidity and mortality in preterm infants. Early diagnosis remains challenging because clinical signs are nonspecific. We evaluated whether stool biomarkers could discriminate preterm infants with NEC from those without NEC. METHODS: We performed an ancillary analysis within the multicenter ClosNEC cohort of infants born before 32 weeks' gestation. Stool samples were collected at diagnosis in infants with confirmed NEC (Bell stage II or higher) and at comparable postnatal ages in preterm infants without NEC. Fecal calprotectin (fCal), human β-defensin-2, α1-antitrypsin (α1-AT), secretory immunoglobulin A (sIgA), cingulin (CGN), and eosinophil-derived neurotoxin were quantified using enzyme‑linked immunosorbent assay (ELISA) kits. Discriminatory performance was assessed using receiver operating characteristic analysis and logistic regression. RESULTS: The analysis included 130 preterm infants: 42 with confirmed NEC and 88 without NEC. Biomarker concentrations differed between groups for all markers except CGN. sIgA showed the best individual discrimination (AUC = 0.82), followed by fCal (AUC = 0.74) and α1-AT (AUC = 0.73). The four-biomarker model yielded an AUC = 0.83, whereas the six-biomarker complete-case model yielded an AUC = 0.86. CONCLUSION: Stool biomarkers discriminated infants with NEC from those without NEC. Our findings support prospective validation in infants evaluated for suspected NEC, including clinically relevant comparator groups. IMPACT: Stool biomarkers distinguished infants with confirmed NEC from infants without NEC in a multicenter cohort. Secretory IgA showed the strongest individual discrimination, with an AUC of 0.82. A six-biomarker complete-case model yielded an AUC of 0.86 in 108 infants. These biomarkers are potential candidates for further evaluation as noninvasive tools for NEC assessment. Validation is needed in infants with suspected NEC and competing neonatal diagnoses.