title: Geographic Variation in Outcome Benefits of Helicopter Transport for Trauma in the United States: A Retrospective Cohort Study.
abstract: OBJECTIVE
  Evaluate the effect of US geographic region on outcomes of helicopter transport (HT) for trauma.
  
  
  BACKGROUND
  HT is an integral component of trauma systems. Evidence suggests that HT is associated with improved outcomes; however, no studies examine the impact of geographic variation on outcomes for HT.
  
  
  METHODS
  Retrospective cohort study of patients undergoing scene HT or ground transport in the National Trauma Databank (2009-2012). Subjects were divided by US census region. HT and ground transport subjects were propensity-score matched based on prehospital physiology and injury severity. Conditional logistic regression was used to evaluate the effect of HT on survival and discharge to home in each region. Region-level characteristics were assessed as potential explanatory factors.
  
  
  RESULTS
  A total of 193,629 pairs were matched. HT was associated with increased odds of survival and discharge to home; however, the magnitude of these effects varied significantly across regions (P < 0.01). The South had the greatest survival benefit (odds ratio: 1.44; 95% confidence interval: 1.39-1.49, P < 0.01) and the Northeast had the greatest discharge to home benefit (odds ratio: 1.29; 95% confidence interval: 1.18-1.41, P < 0.01). A subset of region-level characteristics influenced the effect of HT on each outcome, including helicopter utilization, injury severity, trauma center and helicopter distribution, trauma center access, traffic congestion, and urbanicity (P < 0.05).
  
  
  CONCLUSIONS
  Geographic region impacts the benefits of HT in trauma. Variations in resource allocation partially account for outcome differences. Policy makers should consider regional factors to better assess and allocate resources within trauma systems to optimize the role of HT.
authors.affiliation: *Division of General Surgery and Trauma, Department of Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA †Division of Acute Care Surgery, Department of Surgery, University of Rochester Medical Center, Rochester, NY.
authors.forename: Joshua B
authors.initials: JB
authors.lastname: Brown
authors.forename: Mark L
authors.initials: ML
authors.lastname: Gestring
authors.forename: Nicole A
authors.initials: NA
authors.lastname: Stassen
authors.forename: Raquel M
authors.initials: RM
authors.lastname: Forsythe
authors.forename: Timothy R
authors.initials: TR
authors.lastname: Billiar
authors.forename: Andrew B
authors.initials: AB
authors.lastname: Peitzman
authors.forename: Jason L
authors.initials: JL
authors.lastname: Sperry
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017732:Air Ambulances; D016208:Databases, Factual; D005260:Female; D054625:Healthcare Disparities / Q000706:statistics & numerical data*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D057216:Propensity Score; D012189:Retrospective Studies; D014481:United States; D014947:Wounds and Injuries / Q000401:mortality / Q000628:therapy*; D055815:Young Adult