Driver license renewal policies and fatal crash involvement rates of older drivers, United States, 1986-2011

Background: Older drivers experience elevated risk of motor vehicle crash involvement, injury, and death. Several states attempt to address these risks through driver license renewal policies; however, little is known about their effects.

Methods: Data from 46 U.S. states from years 1986-2011 were examined. Associations between driver licensing policies and population-based fatal crash involvement rates of drivers aged 55 years and older, in 5-year age groups, were estimated using population-averaged negative binomial regression. Estimates were adjusted for seasonality, time trends, other traffic safety laws, and economic factors. Ratios of relative risks (RRR), which compared changes in fatal crash involvement rates of older drivers associated with changes in licensing policies to corresponding changes in fatal crashes of drivers ages 40-54, were computed to account for other possible sources of confounding.

Results: Mandatory in-person renewal was associated with a 31% reduction in the fatal crash involvement rates of drivers ages 85 and older (RRR: 0.69, 95% Confidence Interval [CI]: 0.48-0.97). When in-person renewal was not required, requiring drivers to pass a vision test was associated with a similar reduction for drivers ages 85+ (RRR: 0.64, 95% CI: 0.49-0.85). When in-person renewal was required, however, requiring a vision test was not associated with any additional reduction, nor was requiring a knowledge test or an on-road driving test. Requiring more frequent license renewal and requiring healthcare providers to report concerns about patients' driving ability to licensing authorities were not associated with statistically significant reductions in fatal crash involvement rates of older drivers. No policy examined was found to have a significant impact on fatal crash involvement of drivers younger than 85.

Conclusions: Requiring drivers to renew their license in person, or to pass a vision test if not renewing in person, was associated with significant reductions in population-based fatal crash involvement rates for drivers ages 85 and older. The study could not determine how these effects were achieved, for example by specifically removing unsafe older drivers from the driving population or by fostering premature driving cessation. Other policies examined were not found to reduce fatal crash involvement rates of older drivers.