Older drivers will account for a larger number and percentage of the driving population in the future. Despite typically driving fewer miles than younger drivers, older drivers have the second highest rate of motor vehicle crashes per mile driven, exceeded only by drivers younger than 24 years. Older drivers also tend to have more serious outcomes from motor vehicle crashes than younger drivers. Two recent articles in Canadian Family Physician, one by Hogan and the other by Molnar and colleagues, address the family physician’s role in assessing the older patient’s ability to drive.
Both articles stress that multiple factors can contribute to impaired driving, including medication use, chronic diseases, changes associated with aging, and a combination of these factors. To help physicians identify patients at risk of driving impairment, the American Medical Association has identified “red flags” (http://www.ama-assn.org/go/olderdrivers) that include recent acute illnesses, chronic conditions, the use of certain classes of medications, and the presence of specific symptoms. Molnar and colleagues use this list and data from other sources to propose two acronyms for use in practice—the SAFE DRIVE checklist and the CanDRIVE assessment algorithm. Although not strictly evidence-based, these tools are thought to be appropriate for use in practice. Both articles also provide guidance on eliciting an appropriate driving history from older patients, using questionnaires and toolkits of key questions to ask patients and family members. These cover the patient’s perception of his or her driving ability; criticism of the patient’s driving by others; stress or symptoms caused by or associated with driving; physical symptoms that affect driving ability; and increased difficulty in driving, such as close calls, problems with parking, or getting lost.
The evaluation of the older driver must be individualized and should include assessment of physical and cognitive functions. Experts disagree about the most suitable test of cognitive abilities related to driving. The Mini-Mental State Examination is used widely to assess general cognitive function and screen for dementia, but it does not address visual perception, selective attention, judgment, insight, and the use of alcohol or medications.
The Clinical Dementia Rating (CDR) scale provides a score ranging from zero (no dementia) to 3 (severe dementia). It takes about 40 minutes to complete and addresses six domains, although not all of them are associated with driving. The 1994 International Consensus Conference on Dementia and Driving concluded that physicians should recommend that patients stop driving if they score a 2 or 3 on the CDR. The American Academy of Neurology recommends that patients with Alzheimer’s disease should not drive if they have a CDR score of 1, and that even patients with possible Alzheimer’s disease who score 0.5 on the CDR pose a serious risk and should undergo performance evaluation.
Specialized testing includes occupational therapy assessment and neuropsychological evaluation, but road testing remains the most widely accepted criterion for driving safety. Road testing is expensive, and its availability may be limited. The use of driving simulators has not yet been developed for widespread clinical testing of older drivers.
Both articles emphasize that physicians must be aware of national standards and state and local regulations governing safe driving by older patients. Nevertheless, assisting patients and families with this important decision requires considerable skill in patient assessment and negotiation to implement the necessary changes. Although several tools exist to assist in identifying the “at-risk” older driver and in clarifying the type and severity of the risk, most guidelines are not based on scientific evidence, and significant controversy persists.