title: Effect of trauma systems on motor vehicle occupant mortality: A comparison between states with and without a formal system.
abstract: BACKGROUND
  Population-based studies using a "before-and-after" methodology report a reduction in motor vehicle collision mortality with implementation of statewide trauma systems (TS). However, concurrent improvements in roads, cars, restraint systems, and changes in rates of drunk driving, socioeconomics, speed limits, urban or rural mix, and traffic density may also be responsible for the progressive reduction in mortality rates. We hypothesized that a statewide TS independently reduces injury mortality, irrespective of other factors.
  
  
  METHODS
  Data were acquired from several federal agencies including the Centers for Disease Control (CDC), The National Highway Traffic Safety Administration (NHTSA), the United States Department of Transportation (DOT), and the United States Census Bureau. Age-adjusted motor vehicle occupant (MVO) death rates per 100,000 population were compared in states with and without a TS. Negative binomial regression was used to calculate risk ratios (RR) comparing mortality in TS and non-TS states after adjusting for effects of gender, race, primary seat belt laws, seat belt use, alcohol use, miles traveled, population density, per capita income, types of registered vehicles, and rural or urban mix.
  
  
  RESULTS
  : The number of states with a TS increased from 7 in 1981 to 36 in 2002. Concurrently, nationwide MVO death rates decreased by 2.6 per 100,000 (95% confidence interval 1.2-3.9; p < 0.001). Income, primary seat belt laws, restraint use, speed limits, and rural or urban population distribution (p < 0.05 for all), were independent predictors of MVO mortality, but not presence of a TS (RR 0.95, 95% confidence interval 0.73-1.23; p = 0.68).
  
  
  CONCLUSIONS
  MVO death rates have declined over time, and are lower in TS states. However, the cause is multi-factorial, and cannot be attributed solely to presence of TS. Further studies are needed to identify beneficial components of a statewide trauma system.
authors.affiliation: Department of Surgery, Division of Burn, Trauma and Surgical Critical Care, University of Texas Southwestern Medical School, Dallas, Texas 75390-9158, USA. shahid.shafi@utsouthwestern.edu
authors.forename: Shahid
authors.initials: S
authors.lastname: Shafi
authors.forename: Avery B
authors.initials: AB
authors.lastname: Nathens
authors.forename: Alan C
authors.initials: AC
authors.lastname: Elliott
authors.forename: Larry
authors.initials: L
authors.lastname: Gentilello
mesh_terms: D000063:Accidents, Traffic / Q000401:mortality*; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D011156:Population Density; D012622:Seat Belts; D012959:Socioeconomic Factors; D013221:State Health Plans; D014193:Trauma Centers / Q000458:organization & administration*; D014481:United States / Q000453:epidemiology