511 - Risk and protective factors for development of Necrotizing Enterocolitis in preterms- A retrospective case control study at a single center Neonatal Intensive Care Unit.

Poster Number: 511
Publication Number: 511.426

Nita Shrestha, John H Stroger Jr. Hospital of Cook County, Chicago, IL, United States; Shou-Yien Wu, Chicago Medical School, Rosalind Franklin University, Willowbrook, IL, United States

Background: Necrotizing Enterocolitis (NEC) is a multifactorial and devastating disease of the gastrointestinal tract that affects mostly preterm neonates. 

Objective: To determine the risk and protective factors associated with the development of NEC in preterm infants at a level III NICU. 

Design/Methods: This is a retrospective, 1:2 matched, case control study. We reviewed the data base from our Neonatal intensive Care Unit (NICU) from January 2007 to December 2021. Infants who were less than 37 weeks of gestation and were diagnosed with NEC with Bell stage ≥ stage II A were included as cases. Each case was matched with 2 controls: first by Gestational Age (GA) ±1week and second, by Birth Weight (BW) ±120 grams. Control subjects were chosen within 2 months of the date of birth of cases. In each matched triad, data of perinatal and postnatal clinical conditions were collected from electronic medical records (Table 1). The postnatal day on which NEC was diagnosed in the cases, was used for the feeding and hematologic characteristics data collected in the control group. Out of 44 cases, 27 were < 28 weeks of gestation and were analyzed in a separate category with their respective controls.  

Results:

Among the 44 cases, the Mean ± Standard Deviation of GA was 27.9 ± 4.3 weeks and the mean BW was 1169 ± 705 grams. 27 (67%) cases were < 28 weeks of gestation and 30 (75%) were < 1500 grams at birth. Maternal hypertension, antenatal steroids, chorioamnionitis and inborn delivery were shown to have protective effects in the development of NEC, especially in the  < 28 weeks group (P= 0.007, P= 0.015, P=0.025 and P= 0.001 respectively) as shown in Table 1.

As shown in Table 2, infants with NEC were more likely to receive prolonged duration of antibiotics (>7 days) before the onset of NEC. In the < 28 weeks group, infants who received formula as initial feeding (P=0.02) and those who received higher volume of feeds (118 ± 45 ml/kg/day Vs 79 ± 60 ml/kg/day, P=0.02) were more likely to develop NEC. No significant difference was observed between cases and controls with respect to positive blood cultures, Patent Ductus Arteriosus (PDA) and it’s treatment, Packed Red Blood Cell (PRBC) transfusion and anemic status.  

 Conclusion(s): In our study, maternal hypertension, antenatal steroids, chorioamnionitis and inborn delivery were found to be protective for developing NEC in preterm infants, whereas prolonged duration of antibiotics, formula feeding, and larger amount of feeding were found to be the risk factors, especially in infants less than 28 weeks of gestation. 
Table 1. Baseline Demographic and Perinatal characteristics.*Data is presented as median (interquartile range). P= < 0.05 is statistically significant
PPROM: Preterm premature rupture of membranes, HTN: Hypertension.MgSO4: Magnesium sulfate ; IUGR: Intrauterine growth restriction. NSVD: Normal vaginal spontaneous delivery
Table 2. Comparison of risk factors for NEC.*Data is presented as mean (standard deviation) p= < 0.05 is statistically significant
NEC: Necrotizing enterocolitis; PDA: Patent ductus arteriosus; UAC: Umbilical artery catheter; PCVC: Percutaneous central venous catheter; IVH: intraventricular hemorrhage.