title: Geography and travel distance impact emergency department visits.
abstract: BACKGROUND
  Little has been written about the geographic basis of emergency department (ED) visits.
  
  
  OBJECTIVE
  The objective of this study is to describe the impact of geography on ED visits.
  
  
  METHODS
  A retrospective analysis was conducted of ED visits during a 1-year period at a single institution using spatial interaction analysis that models the pattern of flow between a series of origins (census block groups) and a destination (ED). Patients were assigned to census block groups based upon their verified home address. The study hospital is the only Level I trauma, pediatric, and tertiary referral center in the area. There are 11 other hospitals with EDs within a 40-mile radius. Each patient visit within this radius, including repeat visits, was included. Patients with an invalid home address, a post office box address, or those who lived outside a 40-mile radius were excluded. ED visits per 100 population were calculated for each census block group.
  
  
  RESULTS
  There were 98,584 (95%) visits by 63,524 patients that met study inclusion criteria. Visit rates decreased with increasing distance from the ED (p < 0.0001). Nineteen percent of patients lived within 2 miles, 48% within 4 miles, and 92% within 12 miles of the ED. The Connecticut border, 7 miles south of the ED (p < 0.0001), the Connecticut River, 1 mile west of the ED (p < 0.0001), and the presence of a competing ED within 1 mile (p < 0.0001) negatively impacted block group ED visit rates. Travel distance was related to the percentage of visits that were high acuity (p < 0.0001), daytime (p < 0.01), or resulted in admission (p < 0.0001).
  
  
  CONCLUSIONS
  Geography and travel distance significantly impact ED visits.
authors.affiliation: Baystate Medical Center, Springfield, Massachusetts 01199, USA.
authors.forename: Philip L
authors.initials: PL
authors.lastname: Henneman
authors.forename: Jane L
authors.initials: JL
authors.lastname: Garb
authors.forename: Geoffrey A
authors.initials: GA
authors.lastname: Capraro
authors.forename: Haiping
authors.initials: H
authors.lastname: Li
authors.forename: Howard A
authors.initials: HA
authors.lastname: Smithline
authors.forename: Richard B
authors.initials: RB
authors.lastname: Wait
mesh_terms: D000046:Academic Medical Centers; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005260:Female; D005843:Geography; D006297:Health Services Accessibility; D006801:Humans; D015994:Incidence; D008297:Male; D010343:Patient Admission / Q000706:statistics & numerical data; D012189:Retrospective Studies; D012307:Risk Factors; D014195:Travel; D014481:United States; D014505:Urban Population