The Impact of Hospital Delivery Volumes of Newborns Born Very Preterm on Mortality and Morbidity.

Objective: To examine if the annual patient volume of infants born very preterm (VPT, gestational age <32 weeks) at a hospital is associated with neonatal mortality and morbidity.
Study Design: We performed an observational, secondary data analysis using a 20-year panel of birth certificates linked to hospital discharge abstracts, including transfers in California, Michigan, Missouri, Oregon, Pennsylvania, and South Carolina from 1996 through 2015. The study included all in-hospital VPT deliveries (n = 208 261). Study outcomes were in-hospital mortality or serious morbidity (intraventricular hemorrhage, necrotizing enterocolitis, retinopathy of prematurity, or bronchopulmonary dysplasia), attributed to the hospital of birth. Poisson regression models estimated the risk-adjusted relative risk (RR) for mortality and serious morbidity across different patient volume categories within a given hospital using hospital fixed effects.
Results: The risk of mortality and serious morbidity for VPT infants increased as the number of infants born VPT at a hospital decreased. Compared with VPT delivery volumes >100 infants per year, the risk of mortality increased when a given hospital had VPT delivery volumes < 60 per year, ranging from a RR of 1.13 (95% C.I. 1.02-1.25) for volumes between 50 to 59 and 1.39 (1.19-1.62) for VPT volumes <10, and the risk of mortality or serious morbidity increased when a given hospital had VPT volumes <100, ranging from a RR of 1.05 (1.02-1.08) for volumes between 90 to 99 and 1.27 (1.19-1.36) for VPT volumes <10.
Conclusions: These results suggest that, for VPT infants, the risk of both mortality and mortality or serious morbidity is increased as the VPT volume within a given hospital declines.
Competing Interests: Declaration of Competing Interest Partial support by the Eunice Kennedy Shriver National Institute of Child Health and Human Development (RO1 HD084819). The Pennsylvania Health Care Cost Containment Council (PHC4) is an independent state agency responsible for addressing the problem of escalating health costs, ensuring the quality of health care, and increasing access to health care for all citizens, regardless of ability to pay. PHC4 has provided data to this entity in an effort to further PHC4's mission of educating the public and containing health care costs in Pennsylvania. PHC4, its agents, and staff, have made no representation, guarantee, or warranty, express or implied, that the data -- financial, patient, payor, and physician specific information -- provided to this entity, are error free, or that the use of the data will avoid differences of opinion or interpretation. This analysis was not prepared by PHC4. This analysis was done by the research team at University of Pennsylvania/Children's Hospital of Philadelphia. PHC4, its agents and staff, bear no responsibility or liability for the results of the analysis, which are solely the opinion of this entity.
(Published by Elsevier Inc.)