title: Trauma systems are associated with increased level 3 trauma centers.
abstract: BACKGROUND
  State-supported trauma systems have a proven association with improved mortality, but to date, there are no data reported on what mechanism leads to this benefit. Our hypothesis is that trauma systems with funding support are associated with increased number of trauma centers (TCs).
  
  
  METHODS
  A retrospective population study: data for the number of American College of Surgeons-verified adult TCs in 2010 were obtained from the American College of Surgeons and for state-designated TCs from state departments of health. Population and gross domestic product (GDP) were obtained from the US Census. The main outcome measure was the number of TCs per population and per GDP. Statistical analysis was carried out using the Mann-Whitney U-test and Poisson regression.
  
  
  RESULTS
  There was no association between a trauma system and the numbers of level 1 or 2 centers. In states with funded trauma systems, the numbers of level 3 centers per GDP and per million state population were 4.76 ± 2.37/$100 billion and 1.77 ± 0.51/million people compared with 0.72 ± 1.72/$100 billion and 0.28 ± 0.60/million people for unfunded states (P < 0.05). Poisson multivariate regression identified system funding as an independent predictor of number of level 3 centers.
  
  
  CONCLUSIONS
  Our study shows that the number of level 3 TCs significantly and independently correlated with the presence of a funded trauma system. The number of level 1 and 2 centers showed no such correlation. Further study will determine if increased number of level 3 centers leads to improved clinical outcome.
authors.affiliation: Division of Trauma, Burn, and Surgical Critical Care, Department of Surgery, Brigham and Women's Hospital, Boston, Massachusetts. Electronic address: ekelly1@partners.org.
authors.forename: Edward
authors.initials: E
authors.lastname: Kelly
authors.affiliation: Harvard Medical School, Boston, Massachusetts.
authors.forename: Erica R
authors.initials: ER
authors.lastname: Kiemele
authors.affiliation: Center for Surgery and Public Health, Brigham and Women's Hospital, Boston, Massachusetts.
authors.forename: Gally
authors.initials: G
authors.lastname: Reznor
authors.affiliation: Division of Trauma, Burn, and Surgical Critical Care, Department of Surgery, Brigham and Women's Hospital, Boston, Massachusetts; Center for Surgery and Public Health, Brigham and Women's Hospital, Boston, Massachusetts.
authors.forename: Joaquim M
authors.initials: JM
authors.lastname: Havens
authors.affiliation: Division of Trauma, Burn, and Surgical Critical Care, Department of Surgery, Brigham and Women's Hospital, Boston, Massachusetts; Center for Surgery and Public Health, Brigham and Women's Hospital, Boston, Massachusetts.
authors.forename: Zara
authors.initials: Z
authors.lastname: Cooper
authors.affiliation: Division of Trauma, Burn, and Surgical Critical Care, Department of Surgery, Brigham and Women's Hospital, Boston, Massachusetts.
authors.forename: Ali
authors.initials: A
authors.lastname: Salim
mesh_terms: D012189:Retrospective Studies; D013219:State Government; D014193:Trauma Centers / Q000191:economics* / Q000458:organization & administration*; D014481:United States
keywords: Access to care; Comparative effectiveness; Cost of trauma care; Level 3 trauma center; Trauma; Trauma center; Trauma systems