Objective: To estimate the association of rear seat safety belt use with death in a traffic crash.
Design: Matched cohort study.
Setting: The US during 2000 through 2004.
Subjects: Drivers (10,427) and rear seat passengers (15,922) in passenger vehicles that crashed and had at least one driver or rear passenger death. Data from the Fatality Analysis Reporting System.
Main outcome measures: The adjusted relative risk (aRR) of death for a belted rear seat passenger compared with an otherwise similar unbelted rear passenger.
Results: Safety belt use was associated with a reduced risk of death for rear car occupants: outboard rear seat aRR 0.42 (95% CI 0.38 to 0.46), and center rear seat aRR 0.30 (95% CI 0.20 to 0.44). For rear occupants of light trucks, vans, and utility vehicles, the estimates were: outboard aRR 0.25 (95% CI 0.21 to 0.29), center aRR 0.34 (95% CI 0.24 to 0.48).
Conclusions: If the authors' estimates are causal, traffic crash mortality can be reduced for rear occupants by approximately 55-75% if they use safety belts.