The association of driver age with traffic injury severity in Wisconsin

To quantify the association of driver's age with the risk of being injured, dying, and experiencing injuries of different severity when involved in a motor vehicle crash.

Data from the Wisconsin Crash Outcome Data Evaluation System (CODES) from 2002 to 2004 were used to study 602,964 drivers of a car or truck who were involved in a motor vehicle crash. Odds ratios (OR) or relative risk ratios (RRR) and their 95 percent confidence intervals (CIs) were calculated for age groups, in relation to the outcomes of injury, fatality, and injury severity using logistic regression models, which controlled for sex, alcohol use, urban/rural location, seat belt use, ejection, airbag deployment, vehicle type, and highway class.

Increasing age was strongly associated the risk of dying or experiencing severe injuries for drivers involved in motor vehicle crashes with the greatest risk in drivers 85 years and older. Compared to drivers aged 25-44, drivers 85 years and older had the highest risks for moderate injury (ISS = 9-15; RRR = 5.44, 95% CI: 3.97-7.47), severe injury (ISS = 16-74; (RRR = 4.32, 95% CI: 2.73-6.84), and fatality (OR = 10.93, 95% CI: 7.76-15.38). In contrast, drivers 85 years and older had no increase in risk for minor injury (ISS = 1-8; OR = 0.94, 95% CI: 0.84-1.05).

The oldest drivers involved in motor vehicle crashes had the highest risk for severe injury and fatality. In light of the increasing number of the oldest drivers and their poor outcomes from severe trauma, substantial morbidity can be expected to occur in the oldest drivers. Evidence-based measures to reduce the risks to older drivers should continue to be developed, evaluated, and implemented.