Age, period, and cohort effects in motor vehicle mortality trends by sex and role in crash in the United States, 1980-2010

Introduction: This study assesses the contribution of age, period, and cohort (APC) effects on trends in deaths from motor vehicle crashes (MVC) from 1980-2010 by sex and position in the crash (driver, passenger, pedestrian) to provide evidence for policymakers seeking to reduce MVCs.

Methods:  We use data from the Fatal Accident Reporting Systems (FARS) and 5-year population counts from the Census Bureau to construct age-specific death rates. Since poisson regression models confirm that effects of cohort factors are linearly dependent on age and period, these analyses use the Intrinsic Estimator technique to produce estimates of risks of death for all three effects simultaneously relative to the average of the given age range, period, or cohort, respectively. 

Results: Findings confirm large, significant reductions in MVC deaths over time and highlight differences between men and women, by age and by period. These effects differ by the role of the deceased in the MVC by sex, and vary by age, period and cohort. Similarly, patterns of fatality risks differ by sex when crashes are analyzed by whether alcohol was involved. Risks of fatality in MVC crashes when alcohol was involved declined by period for those aged 15-25 more rapidly than those for which alcohol was not, and exhibited cohort effects similar to non alcohol-related fatalities. 

Conclusions: Results suggest success for reducing risks among young drivers, while highlighting less progress with other groups, such as older pedestrians and younger occupants. Observed differences among male and female drivers may warrant changes in current intervention strategies.