title: Disentangling the effects of risk factors and clinical care on subnational variation in early neonatal mortality in the United States.
abstract: OBJECTIVE
  Between 1990 and 2010, the U.S ranking in neonatal mortality slipped from 29(th) to 45(th) among countries globally. Substantial subnational variation in newborn mortality also exists. Our objective is to measure the extent to which trends and subnational variation in early neonatal mortality reflect differences in the prevalence of risk factors (gestational age and birth weight) compared to differences in clinical care.
  
  
  METHODS
  Observational study using linked birth and death data for all births in the United States between 1996 and 2006. We examined health service area (HSA) level variation in the expected early neonatal mortality rate, based on gestational age (GA) and birth-weight (BW), and GA-BW adjusted mortality as a proxy for clinical care. We analyzed the relationship between selected health system indicators and GA-BW-adjusted mortality.
  
  
  RESULTS
  The early neonatal death (ENND) rate declined 12% between 1996 and 2006 (2.39 to 2.10 per 1000 live births). This occurred despite increases in risk factor prevalence. There was significant HSA-level variation in the expected ENND rate (Rate Ratio: 0.73-1.47) and the GA-BW adjusted rate (Rate ratio: 0.63-1.68). Accounting for preterm volume (defined as <34 weeks), the number of neonatologist and NICU beds, 25.2% and 58.7% of the HSA-level variance in outcomes was explained among all births and very low birth weight babies, respectively.
  
  
  CONCLUSIONS
  Improvements in mortality could be realized through the expansion or reallocation of clinical neonatal resources, particularly in HSAs with a high volume of preterm births; however, prevention of preterm births and low-birth weight babies has a greater potential to improve newborn survival in the United States.
authors.affiliation: Institute for Health Metrics and Evaluation, The Department of Global Health, University of Washington, Seattle, Washington, USA. lahn.straney@monash.edu
authors.forename: Lahn D
authors.initials: LD
authors.lastname: Straney
authors.forename: Stephen S
authors.initials: SS
authors.lastname: Lim
authors.forename: Christopher J L
authors.initials: CJ
authors.lastname: Murray
mesh_terms: D001724:Birth Weight / Q000502:physiology*; D002391:Catchment Area, Health / Q000706:statistics & numerical data; D005865:Gestational Age; D006801:Humans; D007224:Infant Care / Q000706:statistics & numerical data*; D007226:Infant Mortality / Q000639:trends*; D007231:Infant, Newborn; D015233:Models, Statistical; D015995:Prevalence; D012307:Risk Factors; D014481:United States / Q000453:epidemiology