Hospital and Patient Characteristics Associated with Variation in 28-Day Mortality Rates for Very Low Birth Weight Infants

Published In: Pediatrics, v. 99, no. 2, Feb. 1, 1997, p. 149-156

Posted on on January 01, 1997

by Jeffrey Horbar, Gary J. Badger, Eugene Lewit, Jeannette Rogowski, Patricia Shiono

This article examines the hospital and patient characteristics associated with variation in 28-day mortality rates for very low birth weight infants in 62 neonatal intensive care units (NICU) participating in the Vermont Oxford Network Database. Of the over 7,000 infants in the study, 15% died with 28 days of birth. The ratio of the number of observed deaths at an NICU to the number of deaths predicted, based on the characteristics of infants treated at the NICU, varied significantly among units. There was no association between annual patient volume and either mortality rate or standardized neonatal mortality rate (SNMR). Both observed mortality rates and standardized rates were higher at the 24 hospitals with pediatric residency training programs than at the 38 hospitals without such programs. Hospitals with residency programs had higher average patient volumes. In an analysis simultaneously adjusting for patient characteristics, volume, and presence of a residency program, neither volume nor presence of a pediatric residency program was significantly associated with neonatal mortality rate. The conclusion of this article is that there are differences in neonatal mortality rate among NICUs that cannot be explained by differences in the measured admission characteristics of infants, suggesting that the effectiveness of medical care varies among units. However, neither the annual volume of very low birth weight infants treated in a unit nor the presence of a pediatric residency training program was independently associated with neonatal mortality rates for very low birth weight infants. More work will be needed to try to explain what predicts the substantial differences in outcomes found among neonatal intensive care units.

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