Research Papers

Assessing Cognitive, Physical and Driving Behavioural Change in Older Drivers: A Longitudinal Analysis of Candrive Data

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Date added June 30, 2016
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Category 2016 CARSP XXVI Halifax
Tags Research and Evaluation, Session 2B
Author/Auteur Michel Bédard
Stream/Volet Research and Evaluation

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Background/Context: As Canada's population ages, the proportion of older drivers on the road increases. While driving is often integral to maintaining seniors’ independence and community involvement, it is imperative to strike a balance between mobility and safety. The ultimate goal of the Canadian Driving Research Initiative for Vehicular Safety (Candrive) is to extend the safe driving period for older adults. Part of this process includes documentation of longitudinal change in older drivers.

Aims/Objectives: To examine the natural progression of older road users’ driving behaviours, cognition, and physical health over time.

Methods/Target Group: 928 drivers over the age of 70 years were recruited at 7 Canadian sites. Data were collected over a series of five annual assessments. Driving behaviour was quantified via the Driving Comfort Scales (Day and Night), the Driving Habits and Intentions Questionnaire, and the Situational Driving Frequency and Avoidance scales; cognitive tests comprised the Mini-Mental State Examination, Montreal Cognitive Assessment, Trails A and B, and the Motor-Free Visual Perception Test Visual Closure Subtest; and physical measures included the Timed Up and Go test, the Older American Resources and Services questionnaire (activities of daily living), the Cumulative Illness Rating Scale, and count of medications. For participants with a minimum of 3 of 5 possible data points, a series of linear mixed models were employed to examine change in outcome measures over time.

Results/Activities: For the 799 participants included in the analyses, many health and driving behaviour outcomes showed statistically significant changes over time. For example, number of medical conditions (captured by the Cumulative Illness Rating Scale) increased for the 554 participants who completed all five assessments (mean of 6.99 (SD=3.24) at baseline to 10.47 (SD=4.59) by Year 5, p<.001). Also, self-reported driving frequency decreased for this same group (mean score on the Situational Driving Frequency Scale fell from 36.50 (SD=7.02) at baseline to 34.19 (SD=7.86) by Year 5, p<.001). For both of these examples, participants with fewer than five assessments (i.e., withdrawals), demonstrated an even greater rate of change, p<.001. Cognitive measures did not demonstrate statistically significant change, regardless of withdrawal status.

Discussion/Deliverables: Results indicate that participants modified their driving behaviour and experienced a decline in their health over the course of their study involvement. These changes were most salient for those who withdrew from the study. Cognitive performance remained relatively stable for all participants.

Conclusions: The current findings suggest that declines in physical function were met with adaptive strategies to mitigate these changes. However further research is required to confirm these patterns at the individual level.

Michel Bédard