Older drivers, medical condition, medical impairment and crash risk

Abstract

New evidence has appeared to support the fact that the over-involvement of older drivers in traffic accidents disappears when the low mileage bias is taken into account. As a group, older drivers are as safe as or safer than other age groups, and only low mileage older drivers have a high crash rate. Furthermore, the role of the medical condition of older drivers in traffic accidents, as well as the fitness to drive evaluation, are objects of controversy. We examined all this with a cohort of 4316 drivers attending Medical Driving Test Centres for a mandatory fitness to drive evaluation. Our data shows that older drivers (≥75) have a lower crash rate. Medical conditions that impair fitness to drive, as a tendency, increased with advanced age and with lower mileage group. The multivariate analysis of variance showed that there is an effect (p < 0.0001) of age-range and mileage on the annual crash rate per million kilometres driven, while a medical restriction ("fit to drive with restriction") has no effect (p > 0.05). Our data suggests that health status is not associated with increased crash risk for the low mileage group, although further studies are needed.

Findings from the Candrive/Ozcandrive study: Low mileage older drivers, crash risk and reduced fitness to drive

“…After excluding a small number of drivers for whom there were missing data, the group sizes were: Previous studies (Hakamies-Blomqvist et al, 2002;and Alvarez & Fierro, 2008) used the following distance parameters: <3001 km for low mileage, >3000 and <14001 km for middle mileage and >14000 km for high mileage drivers. The parameters in the present study vary slightly, to ensure adequate numbers of respondents especially for the low mileage category.…”

“…The failure to take into account annual mileage when computing crash rates, has been termed the 'low mileage bias'. Janke's subsequent warning to licensing administrators not to become overly alarmed about older drivers' apparent high per-mileage crash rates, has been empirically demonstrated initially by Hakamies-Blomqvist, Raitanen & O'Neill (2002) and subsequently by Langford, Methorst & Hakamies-Blomqvist (2006) and Alvarez & Fierro (2008). All three studies used self-reported driving distances and self-reported crash frequencies to confirm that older drivers' apparent over-involvement in crashes calculated on a per-distance basis, disappeared after controlling for different annual driving distances.…”

Population ageing, gender and the transportation system

“…Mobility is more difficult for people in older years as is shown by: Suen and Mitchell (1998);McGwin et al (2000); Lyman et al (2001);King (2007). Alvarez and Fierro (2008) also indicate the declining health conditions and suffering from long-term illness or disability that increase with advancing years. These impairments affect sensory perception such as visual and cognitive functioning and flexibility and therefore make mobility and the maintenance of an independent life considerably more difficult for older people.…”

Self-Rated Distress Related to Medical Conditions is Associated with Future Crashes or Traffic Offences in Older Drivers

“…Higher driving exposure has been linked with a greater likelihood of experiencing a crash (Owsley et al, 1998;Ball et al, 2006). Conversely, other studies have found that those older drivers driving fewer km were more likely to have a crash (Janke, 1991;Hakamies-Blomqvist et al, 2002;Keall & Frith, 2004b;Langford et al, 2006;Alvarez & Fierro, 2008). …”