title: Degree of urbanization and mortality from motor vehicular crashes.
abstract: OBJECTIVE
  : The purpose of this study is to establish whether motor vehicular crash (MVC) case fatality varies across different urbanization levels in the USA using a representative sample of crashes.
  
  
  METHODS
  : Odds ratios (ORs) and 95% confidence intervals (CIs) for the association between urbanization level [i.e., central city (CC), suburban (SU) and others (OT)] and mortality were estimated in the 1997 - 2010 National Automotive Sampling System Crashworthiness Data System. Multiple logistic regression was used to adjust for confounders. Analysis was repeated for the occurrence of pre-hospital and hospital deaths.
  
  
  RESULTS
  : 49,040,520 weighted occupants were included in the study. The distribution of occupants by urbanization categories was: SU 45%, OT 42%, and CC 13%. Case fatality was higher among OT occupants (0.81%) than among SU (0.51%) and CC (0.37%) occupants. Similar findings were present for pre-hospital deaths (OT 0.52%, SU 0.30%, and CC 0.21%) and hospital deaths (OT 0.29%, SU 0.21%, and CC 0.16%). Multivariate analysis revealed that adjusted odds of death were higher for OT cases [OR=1.55 (1.05-2.30)] than the CC. Adjusted odds of death for SU (OR=1.05 (0.81-1.37) were not different than CCs. Similar but accentuated findings were found for pre-hospital deaths. In contrast, adjusted odds of hospital death were not different among the 3 groups.
  
  
  CONCLUSIONS
  : Occupants of vehicles crashing in OT (i.e., rural areas and small cities) experience a higher likelihood of dying after MVCs than those in CC and SU. Pre-hospital deaths, not hospital deaths, are responsible for this disparity.
authors.affiliation: The Charles C. Mathias, Jr. National Study Center for Trauma and EMS, University of Maryland, Baltimore, MD (GER, PCD); Program in Trauma, University of Maryland, Baltimore, MD (GER); Center for Injury Sciences, University of Alabama at Birmingham (GMG, RLG).
authors.forename: Gabriel E
authors.initials: GE
authors.lastname: Ryb
authors.forename: Patricia C
authors.initials: PC
authors.lastname: Dischinger
authors.forename: Gerald
authors.initials: G
authors.lastname: McGwin
authors.forename: Russell L
authors.initials: RL
authors.lastname: Griffin
mesh_terms: D000063:Accidents, Traffic; D006801:Humans; D016015:Logistic Models; D016017:Odds Ratio; D012307:Risk Factors; D014507:Urbanization