OBJECTIVE:

The objective of this study was to examine the effect of hospital-level factors on mortality of very low birth weight infants using multilevel modeling.

STUDY DESIGN:

This is a secondary data analysis of California maternal-infant hospital discharge data from 1997 to 2002. The study population was limited to singleton, non-anomalous, very low birth weight infants, who delivered in hospitals providing neonatal intensive care services (level-2 and higher). Hierarchical generalized linear modeling, also known as multilevel modeling, was used to adjust for individual-level confounders.

RESULT:

In a multilevel model, increasing hospital volume of very low birth weight deliveries was associated with lower odds of very low birth weight mortality. Characteristics of a particular hospital's obstetrical and neonatal services (the presence of residency and fellowship training programs and the availability of perinatal and neonatal services) had no independent effect.

CONCLUSION:

Using multilevel modeling, hospital volume of very low birth weight deliveries appears to be the primary driver of reduced mortality among very low birth weight infants.