From AccessMedicine from McGraw-Hill

Practice Parameter Guides
Evaluation of Driving Risk in Dementia

 

www.medscape.com

By S. Andrew Josephson, M.D.

Posted: 05/26/2010; AccessMedicine from McGraw-Hill © 2010 The McGraw-Hill Companies

Patients with dementia progressively lose their functional abilities due to cognitive decline. Driving remains a task that most patients and their families hold on to tightly in an attempt to preserve independence. It is the job of the physician to help counsel patients with dementia as to when driving should stop due to safety concerns. Patients, their families, and other drivers must be protected from those whose cognitive skills do not allow safe driving without imposing unnecessary restrictions on patients with cognitive impairment who can still drive safely. In some states there are even legal obligations for physicians to report unsafe drivers with dementia. A recent systematic review (Iverson et al, 2010) aimed to use the available literature to help physicians predict driving ability in their patients with dementia.

The Quality Standards Subcommittee of the American Academy of Neurology performed the systematic review that identified relevant articles published between 1970 and December 2006 on the subject. A total of 502 studies were identified from more than 6000 uncovered by the basic search strategy, and ratings were then made using standardized criteria, leading to graded recommendations.

The authors found level A evidence that higher scores on the Clinical Dementia Rating (CDR), a validated functional scale of dementia severity, were associated with decreased driving ability. However, studies have shown that many (41–85%) of those with mild deficits on the CDR (ratings of 0.5–1, often classified as Mild Cognitive Impairment) were found to be safe drivers via on-road driving tests; therefore CDR appears most helpful in those with scores greater than 1. The CDR was the only predictor of unsafe driving found in this study supported by level A evidence. Level B evidence was found for a caregiver’s rating of the patient’s driving ability as “marginal” or “unsafe” as an accurate predictor of poor driving performance.

Level C evidence supported a number of other risk factors for unsafe driving, including a history of crashes or citations, driving less than 60 miles each week, situational avoidance of driving by the patient, aggressive personality characteristics, and a Mini-Mental Status Examination (MMSE) score of ≤ 24. It is important to note that the MMSE score, which is commonly used in patients with dementia, was not particularly predictive until the value passed below this threshold; at higher scores, the MMSE was not shown to be helpful.

The authors also found level A evidence that a patient’s self-rating of driving abilities was not predictive, nor was a lack of situational avoidance (the latter was level C evidence). There was not enough evidence in the literature to support or refute neuropsychological testing as a predictor of safe driving or whether interventional strategies to improve driving ability were effective.

This important Practice Parameter can be useful for an increasing number of diverse physicians who are asked to advise their patients with cognitive impairment whether continued driving is safe. It appears that patients with a CDR of >1 are at high risk of unsafe driving, and those with a CDR of 0 are at low risk. For those patients with a CDR of 0.5–1, consideration of other risk factors supported by level B and C evidence above should be considered. Central to the CDR rating, as well as to many of the risk factors identified in this review, is a careful history provided not by the patient but by a well-known collateral source such as a family member. Management of patients with dementia can be challenging, but this manuscript provides essential guidance to clinicians to help them advise patients and their families on this important, potentially life-saving topic.

References

AccessMedicine from McGraw-Hill © 2010 The McGraw-Hill Companies

Authors and Disclosures

S. Andrew Josephson, M.D. , Department of Neurology, University of California San Francisco, San Francisco, USA

-From: Medscape Psychiatry,June 01, 2010, http://www.medscape.com/viewarticle/722221, retrieved 6/2/10.

 

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