Risk factors for motor vehicle crashes in older women

Background. Motor vehicle crash and fatality rates are higher per mile driven for elderly drivers, with an exponential increase above age 75. Identifying elderly drivers who are at risk for automobile crashes may help direct interventions to reduce their high rate of injuries and deaths. Methods. Subjects were 1416 women aged 65 to 84 enrolled in the Portland, Ore, site of the Study of Osteoporotic Fractures. Motor vehicle crash information for the years 1986-1995 for each participant obtained from the Oregon State Department of Transportation. ltems from questionnaires, interviews and physical examinations were tested prospectively for association with the occurrence of motor vehicle crashes. Results. About one third of participants (415 of 1416) had a motor vehicle crash during a mean follow-up time of 5.7 years. After adjustment for age and weekly driving mileage, risk factors significantly associated with motor vehicle crashes were a fall in the previous year [hazard ratio (HR) 1.53. 95% confidence interval (CI) 1.26-1.86], a greater orthostatic systolic blood pressure drop (HR 1.11 per 12.5 mm Hg. 95% CI 1.01-1.22) and increased foot reaction time (HR 1.10 per 0.06 second. 95% CI 1.00-1.22). Other neuromuscular tests, functional status, medical diagnoses, vision tests, and cognitive tests did not predict motor vehicle crashes in this study population. Conclusions. This prospective study with extended follow-up of a large cohort of elderly women has identified crash risk factors that can be measures in the clinical setting. Further study is needed to determine if interventions aimed at these risk factors can decrease the risk of motor vehicle crashes.