Visual Test Improves Prediction of Dementia in Primary Care
Patients having the same decline in MMSE score plus an imperfect VAT score have an odds ratio of 9.55 for developing dementia
Administering a visual association test (VAT) in patients with a small decline on the Mini-Mental State Examination (MMSE) during a 2-year period has substantial incremental value for identifying those at elevated risk for developing dementia, according to a study published in the Annals of Family Medicine.
Susan Jongstra, MD, PhD, from Department of Neurology, Academic Medical Center, from the University of Amsterdam, and colleagues investigated the predictive value of changes in MMSE score for 2 years regarding the development of dementia during the 4 to 6 years thereafter and whether adding the VAT improves the overall predictive value. They conducted a cluster-randomized, controlled trial that assessed the efficacy of nurse-led intensive vascular care on the prevention of dementia in a primary care population of 3,526 older adults, aged 70 to 78 years old with a mean follow-up of 6.7 years. Patients were excluded if they received a dementia diagnosis before the 2-year assessment or within 3 months thereafter.
All patients had assessments of cognitive status during follow-up at 2-year intervals, supplemented by available clinical information from general practitioners' electronic health records. An independent committee evaluated dementia diagnoses. To minimize the risk of false-positive diagnoses, all dementia diagnoses were reevaluated based on additional information after 1 more year of follow-up. For this analysis, patients were classified as having incident dementia if they developed dementia at more than 2 years, 3 months from baseline.
A total of 2,690 (76.3%) of the 3,526 trial patients without dementia completed baseline and
2-year follow-up assessments and were included. Overall, 2,648 (98.4%) were evaluated for dementia after a median follow-up of 6.7 years from baseline. Dementia was diagnosed in 157 patients (5.9%) in this group. Patients having a decline of 2 points or more in total MMSE score for 2 years had an odds ratio of 3.55 for developing dementia. Patients having the same decline in MMSE score plus an imperfect VAT score had an odds ratio of 9.55 for developing dementia. A 1-point decline in MMSE score increased the odds of dementia only when the VAT score was imperfect. Dementia risk for patients with a 2- or 3-point decrease in MMSE score and a perfect VAT score did not differ significantly from the average risk of the cohort as a whole.
“Our findings show that the VAT score has incremental value in discriminating between older adults with and without increased risk of dementia, especially among those with a (minor) decline in MMSE score,” the authors concluded. “The risk of developing dementia for older adults with a decrease of 2 points or more on the MMSE and a perfect VAT score was not significantly different from the average risk of the entire cohort.”
Jongstra S, van Gool WA, Moll van Charante EP, et al. Improving prediction of dementia in primary care. Ann Fam Med. May/June 2018 vol. 16 no. 3 206-210. doi: 10.1370/afm.2224