Background: This study was designed to break down the association of age, sex and seat belt use with risk of death for drivers of automobiles involved in a crash into two theoretical components: intrinsic severity of the crash and occupant resilience.
Methods: We studied all 84,338 pairs of drivers and front-seat passengers aged > or = 18 years in passenger cars involved in traffic crashes with victims recorded in the Spanish traffic crash registry between 2000 and 2004. Relative risks (RR) for the association of age, male sex and non-seat belt use with risk of death were calculated with Poisson conditional and unconditional multiple regression models.
Results: For drivers, the risk of death associated with severity of the crash was slightly higher in men (RR = 1.18), and decreased with age (RR = 0.993 per year). However, resilience-dependent risk of death increased with age (RR = 1.028 per year), and especially among unbelted occupants (RR = 4.02).
Conclusions: We conclude that in drivers involved in traffic crashes the association of age, sex and seat belt use with risk of death depends on the component of risk considered: severity of the crash or the occupant's resilience to energy.