WHAT'S KNOWN ON THIS SUBJECT: Significant variation in the mortality of preterm infants has been observed among NICUs. Factors explaining this variation have been difficult to identify.WHAT THIS STUDY ADDS: Sizable center differences in mortality exist, even among similarly sized NICUs in academic centers. Patient characteristics and center treatment rates explain some of the center effect, especially for the youngest infants, but a significant portion of these differences remains unexplained. abstract OBJECTIVE: To examine factors affecting center differences in mortality for extremely low birth weight (ELBW) infants.
METHODS:We analyzed data for 5418 ELBW infants born at 16 Neonatal Research Network centers during [2006][2007][2008][2009]. The primary outcomes of early mortality (#12 hours after birth) and in-hospital mortality were assessed by using multilevel hierarchical models. Models were developed to investigate associations of center rates of selected interventions with mortality while adjusting for patient-level risk factors. These analyses were performed for all gestational ages (GAs) and separately for GAs ,25 weeks and $25 weeks.
RESULTS:Early and in-hospital mortality rates among centers were 5% to 36% and 11% to 53% for all GAs, 13% to 73% and 28% to 90% for GAs ,25 weeks, and 1% to 11% and 7% to 26% for GAs $25 weeks, respectively. Center intervention rates significantly predicted both early and in-hospital mortality for infants ,25 weeks. For infants $25 weeks, intervention rates did not predict mortality. The variance in mortality among centers was significant for all GAs and outcomes. Center use of interventions and patient risk factors explained some but not all of the center variation in mortality rates.
CONCLUSIONS:Center intervention rates explain a portion of the center variation in mortality, especially for infants born at ,25 weeks' GA. This finding suggests that deaths may be prevented by standardizing care for very early GA infants. However, differences in patient characteristics and center intervention rates do not account for all of the observed variability in mortality; and for infants with GA $25 weeks these differences account for only a small part of the variation in mortality. Pediatrics 2013;132:e175-e184 Mr Alleman participated in the conception and design of the study including the analysis plan and in the interpretation of the data and wrote the first and subsequent drafts of the manuscript and helped to revise it critically for important intellectual content; Dr Bell conceived and helped to design the study including the analysis plan, participated in the interpretation of the data, and revised the manuscript critically for important intellectual content; Dr Li helped to design the analysis plan and was responsible for the data management and analysis, performed the analysis with guidance from Mr Alleman and Dr Bell and with advice from Drs Das and Wallace, and helped to revise the manuscript critically for important intellectual content; Both patient factors (eg, gestatio...