Background: The elderly contribute disproportionately to hospital trauma mortality and expense. This population and its traffic fatality rate are increasing. The purpose of this study was to determine how the effect of age on vehicle-related mortality is modified by population density.
Methods: FARS data for vehicle drivers and passengers were analyzed after linkage to census age-specific county population and area estimates. Characteristics of crash fatalities in the elderly (> or =65 years old) were compared with younger victims, for each quartile of county population density.
Results: There were 5905 fatalities among the elderly, and 26,159 among the younger population, yielding annual rates (per 100,000) of 17.6 and 11.4. Rates were higher in counties with lower population density, but always higher among the elderly. Elderly fatal crash victims in all county quartiles were less likely to be male, unrestrained, riding with an intoxicated driver, or traveling over 60 MPH; all these risk factors were more frequent at lower population densities, regardless of age. Fatal crashes at intersections were more likely in the elderly, especially at higher population densities.
Conclusion: Older age and lower population density independently increase vehicle-related mortality. Differing characteristics in each category suggest different preventive strategies.