A matched-cohort analysis of belted front and rear seat occupants in newer and older model vehicles shows that gains in front occupant safety have outpaced gains for rear seat occupants

Abstract

Previous studies have suggested that rear seat occupants are at lower risk of serious injury and death in crashes. However, over the last 10-15 years there have been significant changes in front seat safety systems. The aim of this study was to determine whether there is still a benefit for rear seated occupants compared to front seat occupants. A matched-cohort approach, using data on restrained occupants from the US National Automotive Sampling System (data years 1993-2007), was adopted. Conditional poisson regression modeling was used to evaluate the relative risk of AIS3+ injury in front (passenger and driver) and rear seat occupants, in vehicles of model year 1990-1996 compared to newer vehicles. Occupant age, belt type, and intrusion were additional variables in the model. The relative risk of AIS3+ injury for front and rear occupants was influenced by age and model year. For those aged 16-50 years in older vehicles, the front and rear seat offered similar levels of protection (RR=1.14, CI=1.09-1.19), however in newer model vehicles (1997-2007), the rear seat carried a higher risk of injury (RR=1.98, CI=1.90-2.06). For adults over 50 years, the rear seat carried a higher risk in both older and newer vehicles, and for 9-15 year olds, the rear seat carried a lower risk. These findings suggest that safety for front seat occupants has improved over the last decade, to the point where, for occupants over 15 years of age, the front seat is safer than the rear seat. While the benefit of rear seating for children aged 9-15 years has decreased over time, they are still at lower risk in the rear seat.