THE EFFECTS OF PATIENT VOLUME AND LEVEL OF CARE AT THE HOSPITAL OF BIRTH ON NEONATAL-MORTALITY

Objective.-To examine the effects of neonatal intensive care unit (NIC U) patient volume and the level of NICU care available at the hospital of birth on neonatal mortality. Design.-Birth certificate data linked to infant death certificates and to infant discharge abstracts were u sed in a logistic regression model to control for differences in each patient's clinical and demographic risks. Hospitals were classified by the level of NICU care available (no NICU: level I; intermediate NICU : level II; expanded intermediate NICU: level II+: tertiary NICU: leve l III) and by the average patient census in the NICU. Setting.-All non federal hospitals in California with maternity services. Patients.-All births in nonfederal hospitals in California in 1990 (N=594 104), 473 209 (singletons only) of which were successfully linked with discharg e abstracts. Of these infants, 53 229 were classified as likely NICU a dmissions. Main Outcome Measures.-Death within the first 28 days of li fe, or within the first year of life, if continuously hospitalized. Re sults.-Patient volume and level of NICU care at the hospital of birth both had significant effects on mortality. Compared with hospitals wit hout an NICU, infants born in a hospital with a level III NICU with an average NICU census of at least 15 patients per day had significantly lower risk-adjusted neonatal mortality (odds ratio, 0.62; 95% confide nce interval, 0.47-0.82; P=.002). Risk-adjusted neonatal mortality for infants born in smaller level III NICUs, and in level II+ and level I I NICUs, regardless of size, was not significantly different from hosp itals without an NICU, and was significantly higher than hospitals wit h large level III NICUs. Conclusions.-Risk-adjusted neonatal mortality was significantly lower for births that occurred in hospitals with la rge (average census, >15 patients per day) level III NICUs. Despite th e differences in outcomes, costs for the birth of infants born at hosp itals with large level III NICUs were not more than those for infants born at other hospitals with NICUs, Concentration of high-risk deliver ies in urban areas in a smaller number of hospitals that could provide level III NICU care has the potential to decrease neonatal mortality without increasing costs.