Issue: BCMJ, Vol. 53,
July, August 2011,
page(s) 258 Letters
Douglas C. Drummond, MD
I would like to share some thoughts with your readers on the new 2010 OSMV BC Guide in Determining Fitness to Drive/Cognitive Impairment including dementia. In summary, these guidelines enshrine the use of a cognitive screening test called SIMARD MD and a functional test called DriveABLE.
The new guidelines are likely an improvement on the old way, but many of us involved in dementia care have numerous concerns and questions. The two biggest issues for me are:
• How many false positives will there be with these new tools?
• How will these assessment tools function in the “real world” as opposed to the university environment in which they were developed?
The sum total of what we know about the SIMARD MD is found in a recent paper by Bonnie Dobbs and Donald Schopflocher. DriveABLE was developed by Allen Dobbs (husband of Bonnie) and his collaborators at the University of Alberta and then spun off into a private company.
DriveABLE has two parts: an in-office assessment using a computer, and unless one fails that miserably, then an on-road evaluation.
How will these tools function in the real world? The validation work on DriveABLE has likely not been closely scrutinized or duplicated by academics other than the developers. It would be interesting to see what Cochrane-type reviewers would say about their methodology.
In the case of the SIMARD MD, I note that the study participants had a mean educational level of about 12.5 years, which I would estimate to be at least 3 years greater than my patient population. How would all comers perform on this test? The undereducated? ESL? No English at all? Aphasics?
Below a cut-point of 30 on the SIMARD MD, one is considered ineligible to drive; and yet I note in Dr Dobbs’s paper that 14% of those who failed the test went on to pass the road test. Is it acceptable to restrict the driving privileges of those 14% who were misclassified? I further note that five of Dr B. Dobbs’s sample of “healthy controls” failed their on-road evaluation. Were they cognitively impaired drivers or false positives?
My suggestion to the Superintendent of Motor Vehicles is this: Study the performance of these tests in the real world. Take a sample of cognitively well 75- to 85-year-old drivers, all Road Stars, all regular drivers, and put them through these tests to see what kind of false positive rate these assessment tools have.
Maybe seniors really are disadvantaged by the Playstation-like environment of the in-office DriveABLE. Do another study on the cognitively impaired to confirm the performance of the SIMARD MD and the in-office DriveABLE against the on-road test. Do the testing in BC facilities and have the study conducted by investigators at arm’s length.
And please do it before I get any older, because these tests scare me a little!
—Douglas C. Drummond, MD