title: Primary care spatial density and nonurgent emergency department utilization: a new methodology for evaluating access to care.
abstract: OBJECTIVE
  To determine the spatial and demographic characteristics of pediatric patients who make nonurgent visits (NUVs) to an urban pediatric emergency department (ED). We hypothesized that the rate of NUVs would be inversely associated with the spatial density of primary care providers (PCPs).
  
  
  METHODS
  A retrospective, cross-sectional analysis was conducted for all visits to Washington, DC's principal pediatric ED between 2003 and 2006. NUVs were defined by a unique algorithm combining resource allocation, ambulatory-sensitive diagnoses, and billing data. Multivariate linear regression analysis was used to determine the association of PCP density and demographic variables on the spatial rate of NUVs.
  
  
  RESULTS
  Over the 4-year period, 35.1% (52,110) of the 148,314 ED visits by Washington, DC, residents were nonurgent. NUVs were most associated with neighborhood median household income <$40,000 and low spatial density of PCPs. For every 1-unit increase in PCP density, the spatial rate of NUVs decreased by 9%. The odds of a visit being nonurgent were significantly higher for African Americans and Hispanics than for whites (odds ratio [OR] 2.4, 95% confidence interval [CI] 2.19-2.64; and OR 2.6, 95% CI 2.36-2.86, respectively), for patients using public insurance versus private (OR 1.46, 95% CI 1.42-1.50), and for patients age <5 years (OR 2.66, 95% CI 2.60-2.72).
  
  
  CONCLUSIONS
  Low spatial density of primary care is strongly associated with nonurgent ED utilization. Improving spatial distribution of primary care may decrease ED misuse and improve access to the medical home.
authors.affiliation: Department of Pediatrics and Emergency Medicine, Children's National Medical Center, George Washington University School of Medicine and Health Sciences, Washington, DC 20010, USA. dmathiso@childrensnational.org
authors.forename: David J
authors.initials: DJ
authors.lastname: Mathison
authors.forename: James M
authors.initials: JM
authors.lastname: Chamberlain
authors.forename: Nuala M
authors.initials: NM
authors.lastname: Cowan
authors.forename: Ryan N
authors.initials: RN
authors.lastname: Engstrom
authors.forename: Linda Y
authors.initials: LY
authors.lastname: Fu
authors.forename: Anthony
authors.initials: A
authors.lastname: Shoo
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Teach
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D004219:District of Columbia; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005843:Geography; D006297:Health Services Accessibility / Q000706:statistics & numerical data*; D006300:Health Services Misuse / Q000706:statistics & numerical data; D054625:Healthcare Disparities / Q000706:statistics & numerical data*; D006801:Humans; D007223:Infant; D016014:Linear Models; D015999:Multivariate Analysis; D016017:Odds Ratio; D058007:Physicians, Primary Care / Q000706:statistics & numerical data*; D012189:Retrospective Studies; D014505:Urban Population