Risk of motor vehicle crash for older adults after receiving a traffic charge: A case-crossover study.

Objective: After the age of 65, the number of motor vehicle crashes per mile driven increases. Traffic-related charges issued by law enforcement can help identify drivers who are at a higher risk of having a crash. This study examines the relationship between motor vehicle crashes and traffic-related charges among older adult drivers.

Methods: Iowa Department of Transportation crash data from 2011-2012 were linked with Iowa Court Information System data for moving violations that occurred during 2009-2012 for drivers over the age of 50. A time-stratified case-crossover design was used matching on time periods 1 year apart. Case exposure was defined as having a traffic-related charge 30 days before the crash. Control exposure was the same 30-day time period 1 year before the crash for each individual. Conditional logistic regression was used to analyze the self-matched pairs. Additional time periods of 31-60, 61-90, 91-120, 121-150, 151-180, and 181-210 days before the crash were also assessed.

Results: There were 38,171 adults at least 50 years of age with an Iowa driver's license who were involved in a crash in Iowa between 2011 and 2012. In addition, 13,129 adults over the age of 50 received a charge during 2009-2012. Relative to the control time period, experiencing a traffic-related charge in the 30-day time period before the crash increased the risk of a crash by 21% (odds ration [OR] = 1.21, 95% confidence interval [CI], 1.03-1.42) for all drivers included in the study. This crash risk was similar for adults aged 50-64 (OR = 1.20, 95% CI, 1.00-1.45) and adults 65 and older (OR = 1.24, 95% CI, 0.90-1.72). In the 30 days after receiving a traffic-related charge, the risk of a crash was also increased for crashes occurring in adverse weather (OR = 1.79, 95% CI, 1.12-2.84) or during night, dawn, or twilight (OR = 1.89, 95% CI, 1.31-2.72).

Conclusions: A traffic-related charge for an adult over the age of 50 indicates an increased risk of experiencing a crash in the 30 days following the charge. The risk for crashes occurring in adverse conditions or outside of daylight hours was also increased in the 30 days after receiving a traffic-related charge. The risk of experiencing a crash decreases as time passes after receiving a charge. Measures to restrict or increase driving safety during these conditions could help reduce the crash risk for older adults who receive a traffic-related charge.