A Prospective Cohort Study of Fecal MiR-223 and MiR-451a As Noninvasive and Specific Biomarkers for Diagnosis of Necrotizing Enterocolitis in Preterm Infants

Objective: The objective of this study is to evaluate the usefulness of fecal microRNA (miR)-223 and miR-451a, as novel noninvasive biomarkers for early diagnosis of necrotizing enterocolitis (NEC) in preterm infants.

Methods: Among the top-listed target miRNAs in our previous differential microarray analysis, miR-223 and miR-451a were quantified in a pilot validation case-controlled study (NEC vs. non-NEC/nonsepsis infants; n = 6 in each group). A definitive prospective cohort study (n = 218) further assessed their clinical usefulness as noninvasive and specific diagnostic biomarkers. Fecal calprotectin was quantified in parallel for comparison.

Results: Of 43 proven NEC cases in the cohort study, 24 (55.8%) had fecal samples recovered within the first 3 days of clinical presentation. Fecal miRNA-223 (10.5 fold), miR-451a (4.5 fold), and calprotectin (2.1 fold) concentrations were significant higher in NEC compared with the non-NEC group (p < 0.009). Accepting a minimum sensitivity of 0.75, the positive predictive values (PPVs) ranged between 0.19 and 0.20. Combining fecal biomarkers and CRP (Day 1) could marginally increase the PPVs (0.31-0.34) but adversely lowered the sensitivity (0.54-0.63).

Conclusions: Although fecal miRNA biomarkers and calprotectin concentrations were significantly higher in the NEC group, the considerable overlapping of concentrations between groups and low recovery of stool specimens within 72 h of clinical presentation rendered fecal noninvasive tests of limited clinical value in guiding diagnosis of NEC during the acute phase. A further study is underway to evaluate their roles in surveillance for predicting high-risk premature infants developing NEC.