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Abstract
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The paper by Ross and colleagues (Older drivers in Australia: Trends in driving status and cognitive and visual impairment. J Am Geriatr Soc 2009;57:1868–1873.) adds useful information on older drivers and health status, but we are concerned that their definition of 'possible cognitive impairment' (a Mini-Mental State Examination Score (MMSE) of 24–26) may not be an accurate reflection of a clinical condition relevant to driving, and the description of the proportion of those driving with dementia does not adequately reflect the relatively preserved driving skills in the first few years of dementia. Taken together without further qualification, these may aggravate negativity in popular and professional opinion about older drivers, one of the safest groups of drivers in the population.
The use of cutoff points with the MMSE to classify cognitive impairment raises some concern, given the significant minorities who will be misclassified by these cutoff points. Even if a MMSE score of 24 to 26 could be considered to reflect mild cognitive impairment (MCI), there is no evidence that MCI is a risk factor for impairment of transport mobility or safety, consistent with the lack of functional decline inherent in its definition. If considered to represent an early form of dementia, this should be considered in terms of people categorized as having “dementia.” Given that there is a significant body of evidence suggesting that driving safety is preserved in the first few years of dementia, any potential hazard to the general public, as well as reduction of personal mobility, is likely to be mitigated.
The message to driver licensing authorities arising from this article is that considerably fewer than 2% of older drivers are likely to suffer from dementia that may affect traffic safety (a more-detailed breakdown of the MMSE of those continuing to drive might allow for some better calculation of this), and careful consideration should be given as to whether this warrants screening by accepted public health criteria, given the negative overall effect in jurisdictions that perform medical screening of older drivers.
The message to healthcare professionals is that opportunistic screening of older people during healthcare consultations for dementia and cognitive impairment should include an assessment of transport and driving, with a view to planning the optimum balance of preserved mobility and safety. |