Age-based variability in the association between restraint use and injury type and severity

Abstract

Purpose: Previous studies have shown elderly individuals receive less relatively less protection from seat belts against fatal injuries, however it is less clear how seat belt protection against severe and torso injury changes with age. We estimated age-based variability in seat belt protection against fatal injuries, injuries with maximum abbreviated injury scale greater than 2 (MAIS3+), and torso injuries. Methods: We leveraged the Crash Outcome Data Evaluation System (CODES) to analyze binary indicators of fatal, MAIS3+, and torso injuries. Using a matched cohort design and conditional Poisson regression, we estimated age-based relative risks (RR) of the outcomes associated with seat belt use. Results: Seat belts were highly protective against fatal injuries for all ages. For ages 16-30, seat belt use was associated with 66% lower risk of MAIS3+ injury (RR 0.34, 95% CI 0.30, 0.38), whereas for ages 75 and older, seat belt use was associated with 38% lower risk of MAIS3+ injury (RR 0.62; 95% CI 0.45, 0.86). The association between restraint use and torso injury also appeared to attenuate with age. Conclusions: Seat belt protection against MAIS3+ and torso injury attenuated with age. We encourage that injury prevention continues to be tailored to vulnerable populations like the elderly.