State-level clustering of safety measures and its relationship to injury mortality

This article proposes a social model of investigating injury mortality. The authors hypothesize that (1) state-level laws and regulations on safety cluster together in one or more groupings; (2) groupings of safety measures play a significant role in injury mortality; and (3) injury mortality is very highly associated with social structural variables. There is a clustering of safety policies, with five factors explaining 67 percent of variance, although no "master factor" was discovered. The strongest factor, explaining 21 percent of variance, includes three gun laws and low speed limits before the 1973 federal law. One factor is the most global in that it taps three distinct areas, including helmet laws, minor blood alcohol levels, and smoke detectors, though it only explains 7.5 percent of variance. The only factor that remains in a regression for injury mortality is one that includes strong seat belt laws and strong enforcement of those laws, though in the direction opposite to that hypothesized. This factor, along with percentage rural and environmental spending per capita, is significant for both motor vehicle and non-motor vehicle mortality. For motor vehicle mortality alone, deaths are higher in states with higher percentages of Hispanics and fewer people receiving food stamps and AFDC. Many factors that usually predict individual injury mortality do not hold at the state level, suggesting the usefulness of looking at social factors for new insights into injury mortality and prevention.