Mortality and Seatbelt Use in Rear-Seated Adults Before and After Passage of Primary Rear Seatbelt Legislation: Findings from the Fatality Analysis Reporting System

Background. Seatbelt use, long associated with decreased motor vehicle mortality, is reported to be lower among rear-seated passengers. In an effort to increase belt wearing in rear-seated adults, some states have passed primary rear seat belt laws. This study examines belt use and mortality pre- and post-law in states transitioning to a primary rear seat belt law.

Methods. The Fatality Analysis Reporting System and U.S. Census data were used to examine primary rear-seat belt laws on rear-seat belt use and mortality rates (n=6,183) in 9 states (Alaska, Delaware, Illinois, Kentucky, Maine, Rhode Island, South Carolina, Washington and Wisconsin) that transitioned to a primary law between 2000-2013. Multilevel logistic regression with fixed effects was used due to multiple rear-seated occupants (1.4 ±SD 0.6) in vehicle models 1970-2013.

Results. Compared to pre-law, primary rear-seat belt laws were associated with an increase in rear-seat belt use (OR: 1.65, 95% CI: 1.45-1.88, p<0.0001) and lower mortality (OR: 0.25, 95% CI: 0.21-0.29, p<0.0001) after controlling for covariates. Of the 9 states, 6 (67%) showed declines in mortality, although half of these began to decline before the transition. Age, gender and vehicle type were associated with differential belt use and mortality.

Conclusions.  Rear-seat belt use increased and mortality declines were observed in a majority of states transitioning to a primary law. However, rear-seat mortality began to decline in several states prior to the legislation’s effective date suggesting the need for further study of other factors that may have influenced the observed improvements.