Update on the Effectiveness of High Retention Seats in Preventing Fatal Injury in Rear Impacts

Abstract

Purpose: Starting in 1997, General Motors (GM) introduced high retention seats in new model vehicles to improve rear impact safety. The seat allowed the occupant to pocket into the seatback and had increased strength and improved head restraint coverage. The initial 4-year safety trends were evaluated using the 1991–2000 Fatality Analysis Reporting System (FARS). The reduction in odds of fatal injury was 30.4% (95% confidence interval [CI], 0.9–51.1, P <.05). This study updates the earlier one by adding 8 years of FARS data.

Methods: The 2001–2008 FARS was analyzed for rear impacts of 1992 to 2008 model year GM vehicles that transitioned to high retention seats. The number of fatal and nonfatal injuries to drivers and right-front passengers was determined in vehicles with baseline (earlier designs) and high retention seats. The odds ratio for fatal injury and the change in fatality risk were determined with ±95% confidence intervals, z-statistic, and significance level. The data were further subdivided by passenger car, light truck (truck, SUV, and van) and driver-only crashes.

Results: Based on 9,570 drivers and right-front passengers in fatal rear impacts in 1991–2008 FARS data, the fatality risk was 16.6% (95% CI, 15.1–18.3) in vehicles with high retention seats and 27.1% (95% CI, 26.1–28.1) in vehicles with baseline seats. The reduction in odds for fatal injury was 46.3% (95% CI, 39.3–52.4) with high retention seats and it was statistically significant with z = 9.982, P <.0001. The reduction in odds for fatal injury was similar for occupants in passenger cars at 45.4% (95% CI, 35.4–53.8) and light trucks, SUVs, and vans at 45.0% (95% CI, 28.8–57.5) using 2001–2008 FARS; however, the fatality risk was higher in passenger cars, at 23.1% (95% CI, 20.6–25.7), than in light trucks, SUVs, and vans, at 8.7% (95% CI, 7.0–10.7).

Conclusions: Vehicles with high retention seats significantly reduced the odds for fatal injury by 46.3% (95% CI, 39.3–52.4, P <.0001) in rear impacts compared to vehicles with earlier seat designs. The new generation of yielding seats has significantly improved occupant safety in rear impacts.

Keywords:

• rear crashes
• fatalities
• seats
• injury risks