Center differences in NEC within one health-care system may depend on feeding protocol

We tabulated the incidence of necrotizing enterocolitis (NEC) during a recent 4-year period among three neonatal intensive care units (NICUs) within a single health-care system. We then sought associations to explain differences in NEC incidence between the centers. Between January 1, 2002, and December 31, 2005, 6787 neonates were admitted to the three NICUs. The incidence of NEC (Bell's stage II or higher) among these patients was correlated with birthweight, gestational age, maternal and neonatal demographics, and various events and practices. These events and practices included feeding practices, the management of patent ductus arteriosus, rates of systemic bacterial and fungal infection, transfers to the regional children's hospital for surgical treatment, and mortality rate. Bell's stage II or higher NEC was documented in 131 of 6787 NICU patients. The incidence was 7.4% among those with birthweights <750 g (16 of 217), 6.9% among those of birthweights 750 to 1250 g (36 of 519), and 1.3% (79 of 6051) among those with birthweights >1250 g. Center A had an incidence of NEC significantly higher than the other two, accounting for 72% of the total cases (94 of 131). Among patients <1250 g, Center A had a rate of NEC of 14.5%; Centers B (2.3%) and C (2.3%) had lower rates ( P<0.0001). After controlling for gestational age, birthweight, small for gestational age status, and Apgar scores, the overall odds ratio of developing NEC in Center A, compared with the other two, was 21.6 (95% confidence interval, 14.7 to 31.6). This difference could not be accounted for by differences in maternal or neonatal demographic characteristics, bed occupancy rates, or a higher incidence of culture-proven nosocomial bacterial or fungal infections. Although the incidence of NEC was significantly higher at Center A, the percentage of patients with NEC transferred to the children's hospital for surgical evaluation and treatment was similar. The mortality rate of patients who developed NEC was similar among the three hospitals. Centers B and C utilize standardized feeding guidelines. During each of the 4-year study periods, one of three NICUs within the same health-care system had a higher incidence of NEC than the other two. Once NEC developed, the outcome was similar in all three NICUs. The higher incidence in Center A could not be explained by differences in demographics, socioeconomics, or systemic nosocomial infections. Similarities in feeding practices between Centers B and C suggest to us that these may be responsible, at least in part, for the differences in the incidence of NEC. Changing the feeding practices at Center A to those at Centers B and C is planned to test this theory.