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Using "Age" as a Fitness-to-Drive Criterion for Older Adults

The aging of the Canadian population is transforming the demographics of the driving population. In 1996, about one-half of seniors living in private households (1.7 million) were driving a vehicle (i.e., car, mini-van or light truck). It is anticipated that the number of seniors living in Canada will increase exponentially, reaching 23% by 2041.[1] Taking this demographic growth into account, the number of older drivers is expected to more than double over the next few decades.[2] Drivers over the age of 80 years are the fastest growing segment of the driving population in Canada.[3] These observations underlie the need to examine the subject of fitness to drive in older adults.

Previous research has indicated that as a person ages, normal physiologic changes and age-associated medical conditions may compromise the ability to operate a motor vehicle safely.[4] The distinction between changes associated with “normal aging” and those associated with “age-related medical conditions” underlies the concepts of primary and secondary aging.[5] Primary aging refers to the intrinsic processes of biological aging that are genetically determined and take place with the passage of time in spite of good health and in the absence of disease. Secondary aging refers to age-related deterioration that is pathological and results from extrinsic factors, including disease, environmental influences, and behavior. These effects are referred to as secondary because, although they are age-associated, people can theoretically age without experiencing them. Although a theoretical distinction is drawn between these forms of aging, in practice the distinction is often unclear or is not made. Unfortunately, then, often what has been attributed to age is really that which was due to disease, or disability, not age per se. For example, senile dementia (severe cognitive impairment among the old) was once considered a normal part of the aging process.[6] We now know that, far from being normal or inevitable, these conditions are the result of some specific organic brain injury or disease (e.g., Alzheimer’s disease). The failure to clearly distinguish between factors associated with normal aging and those related to age-associated conditions or diseases must be kept in mind when reviewing the literature concerning driving performance and age.

It has been noted that among all drivers age 65 and older it is the oldest drivers who pose more risks to themselves and the public. For example, statistics from the U.S. National Highway Traffic Safety Administration (1996) indicate that the rate of crashes per miles driven begins to rise at age 70, and increases rapidly at age 80.[7] Furthermore, older drivers are four times more likely than younger adults to be hospitalized following a motor vehicle accident, and their recovery is slower.[8] As well, older drivers commit several moving vehicle violations at higher rates than drivers in other age groups.[9]

On the other hand, persons age 65 and older are relatively safe drivers. In British Columbia, for example, older drivers comprise 13.6% of the total driver population but are responsible for only 9.2% of the accidents and fatal collisions.[10] Seniors also drive fewer miles than any other age group. Other research suggests that when crash rates are adjusted for miles driven, the motor vehicle crash morbidity and mortality rates for older adults are similar to those of younger adults.[11]

Despite concerns raised by the research on accident rates in older adults, surprisingly little research has addressed evaluating driver competence or methods for identifying potentially unsafe older drivers[12]. Similarly, little is known about the consequences of driving cessation for the individuals and their families. The research available suggests that decisions about continued driving can be very emotionally charged and may lead to family conflict including physical violence.[13] Not only, then, does loss of driving privileges mean loss of personal independence and, potentially, social isolation, but it may also have an impact on family relationships as it is the family that ultimately must ensure compliance with driving restrictions. [14]

The question remains, then, as to whether the abilities of older drivers are compromised because of age itself, or because of age-associated risk of having one or more medical conditions that can affect driving. For example, recent studies show that many medical conditions (e.g., diabetes, cardiovascular disease, and/or other neurological conditions) increase the risk of at-fault crashes among drivers of all ages, though many of these conditions are age-related.

These studies, coupled with the changing demographics of Canadian society, highlight the need for a review of the current laws regulating fitness to drive in the context of age. In all provinces, testing of fitness to drive includes at least two components: tests relating to ability to drive (for example, literacy, knowledge of driving rules, and actual driving); and medical tests (such as vision, psychological, and physical). It is primarily the latter type of testing in which age is either specifically used as a trigger for testing or is, by implication, a factor in determining fitness to drive. To the extent that those laws adopt age as a determinant in evaluating fitness to drive, the legitimacy of such laws are open to attack.  As the Supreme Court of Canada stated in 1999, driving "is a privilege most adult Canadians take for granted" and one which "must not be removed on the basis of discriminatory assumptions founded on stereotypes of disability, rather than actual capacity to drive safely"[15]. The laws, and the extent to which they may be subject to challenge, are discussed in Parts 2 and 4 of this study.

In considering the use of age as a trigger in evaluating medical fitness to drive, the broader question arises whether it is a reliable gauge.  The enforced medical evaluation of cognitively intact older adults may well fail to address the larger public policy of ensuring road safety by granting licenses only to those who are fit to drive.  On the other hand, screening procedures to identify high-risk individuals are clearly needed. The extent to which age-related medical conditions affect driving is examined in Part 3 of the paper.

Part 5 presents the views of seniors and health care providers concerning the adequacy of the present age-based procedures used in British Columbia for identifying problem drivers and the types of changes to the present procedures that may prove beneficial. Finally, Part 6 summarizes all of the material from parts 2 through 5 and presents the views of researchers and representatives of licensing authorities in BC and Alberta concerning our summary.

The advantages and disadvantages of age as a marker for fitness-to drive re-evaluation are addressed and recommendations arising from our research are presented.