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AAN Quality Standards Subcommittee updates practice parameter for evaluation, management of driving risk in patients with dementia

Tuesday, April 27 2010 | Comments

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What's This? The Quality Standards Subcommittee of the American Academy of Neurology (AAN) updated the 2000 practice parameter focused on driving risks in patients with dementia.

The goals of the practice parameter update were to determine the usefulness of various patient assessments, including measures of dementia severity, patient and caregiver reports, and a patient's driving history, in predicting poor driving performance, based on a literature review of the current evidence. In addition, the committee evaluated the current state of evidence to support or refute specific interventions to reduce the risk of unsafe driving in patients with dementia.

The group reviewed studies of patients with dementia or mild cognitive impairment (MCI). If studies of drivers with dementia were unavailable, the group evaluated studies of aged drivers, noting that there is a strong correlation between aging and dementia and that these studies frequently identified cognitive impairment among the participants. However, the evidence obtained from such studies was regarded as weaker than evidence obtained from patients with dementia.

Regarding predictors of poor driving performance, the AAN concluded that the Clinical Dementia Rating (CDR) scale is useful for identifying patients at increased risk for unsafe driving (Level A recommendation). The subcommittee cited 2 Class I and 2 Class II studies suggesting that patients with a CDR of 1 and, in some cases, patients with a CDR of 0.5 were more likely to meet criteria for unsafe driving relative to patients with a CDR of 0. However, the group acknowledged that 41% to 85% of patients with CDRs of 0.5 or 1 in these studies were still found to be safe drivers in an on-road driving test (ORDT).

In addition, other characteristics/assessments were judged to be probably (Level B) or possibly (Level C) useful for identifying patients at increased risk, including a caregiver's rating of a patient's driving ability as marginal or unsafe (Level B), a history of motor vehicle crashes in the previous 1 to 5 years or traffic citations in the previous 2 to 3 years (Level C), reduced driving mileage or patient reports of situational avoidance (Level C), Mini-Mental State Examination scores of <=24 (Level C), and aggressive or impulsive personality characteristics (Level C).

The group added that 2 characteristics should be considered not useful for identifying safe drivers--a patient's self-rating of driving ability as safe (Level A) and a lack of situational avoidance (Level C).

There was insufficient evidence to support or refute the use of neuropsychological testing to evaluate driving risk (Level U). Although studies have confirmed a link between driving impairment and impairment in individual cognitive domains, no study evaluated in the AAN's literature review adequately controlled for both the presence of dementia and dementia severity.

There was also insufficient evidence to support or refute the benefits of interventional strategies for drivers with dementia (Level U).

The AAN offered sample questionnaires that physicians might use with patients and caregivers to obtain relevant information about predictors of poor driving performance and offered an algorithm to assist physicians in making a qualitative estimate of driving risk. The group recommended that patients at higher risk of unsafe driving agree to surrender their driving privileges or agree to undergo a professional/governmental driving evaluation, with reassessment every 6 months.

The AAN cautioned that the current practice parameter is intended to help physicians make an evidence-based estimate of driving risk in a clinical context; however, these guidelines are not designed to help physicians interpret and comply with subjective statutory requirements in various states mandating that physicians report dementia that "could," "may," or "is likely to" lead to impaired driving. (Iverson DJ, et al. Neurology 2010;74:1316-1324.)

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