An algorithm using two well-known tests has shown strong accuracy (91%) in predicting whether an older driver can pass an on-road driving evaluation according to a new study published in the Journal of the American Medical Directors Association .
The Fit2Drive algorithm combines the Mini-Mental State Exam (MMSE), a 30-point dementia screening tool that has been found in several studies to have an association with driving ability, and the Trails B test, which gauges cognitive flexibility and set-shifting (task switching), considered to be measures of executive functioning.
Algorithm Available for Providers
The algorithm is clinically available and providers can fill in patients’ information and results of the two tests at the Fit2Drive website. Results may help physicians with often-difficult conversations with older patients about driving when they present with cognitive concerns.
Families report it is one of the most difficult conversations they have with a loved one and doctors are often asked to be part of the conversation. This is particularly difficult when, often, little objective information is available. In the past, a clinical rule of thumb has been that people diagnosed with Alzheimer’s disease or related dementias (ADRD) will usually be able to drive for 3 years after diagnosis.
“[T]he anger, tears, and frustration on the part of the individual patient and the lack of objective data to guide provider recommendations are the driving forces behind our effort to develop a highly accurate, evidence-based predictor of the ability to pass an on-road driving test,” the authors write. They added that the goal of the study was to identify the smallest number of cognitive test results that could predict likelihood of passing an on-road driver evaluation.
A number of tests were evaluated for the algorithm, but the combination of Trails B in seconds and MMSE using the highest scores of the serial 7s (counting back from 100 by 7s) or WORLD spelled backward accounted for the highest correlation with passing the on-road driving test, according to the authors, led by Ruth Tappen, EdD, FN, with the Christine E. Lynn College of Nursing at Florida Atlantic University, in Boca Raton.
A receiver operator characteristic (ROC) analysis was conducted on the linear combination of the two assessments.
“Because an ROC of 0.70 is considered to be the minimal requirement [for predictive value], 0.80 is considered good, and higher than 0.90 is excellent, these findings [with 91% area under the curve] suggest excellent accuracy using these two cognitive tests in this population,” the authors write.
For this analysis, researchers included 412 older drivers (179 men and 233 women) with an average age of 80. T he study was conducted at the Florida Atlantic University’s Memory Center and Clinical Research Unit. Participants included those who received a driving evaluation at the Memory Center and agreed to have their results included in the Driving Repository, and community-based older drivers who volunteered to participate.
Limitations of the Study
There were marginal differences between sexes on the measures, but they were not significant. The sample was composed of relatively well-educated people, primarily of European American ethnic origin, which is a consideration in generalizing the results.
Among other limitations are that physical and sensory factors, in addition to cognitive issues, may affect an individual’s ability to drive safely and are not included in the algorithm. Sensory disabilities, including reduced visual acuity caused by binocular field vision loss, contrast sensitivity, glare sensitivity, and other conditions, may affect driving ability as well as the ability to fully rotate the head and neck. Medical conditions affecting the cardiovascular, neurological, and orthopedic systems can also influence driving ability.
“Future studies should involve more diverse samples and a greater variety of driving challenges, including school zones and multilane highways, which are not included in the study,” the authors write.
The study received grant support from the State of Florida Department of Health and the Ed and Ethel Moore Alzheimer’s Disease Research Program.