Remote Test Reliably Assesses Cognitive Function in MS

An electronic version of the Symbol-Digit Modalities Test (eSDMT) was feasible and reliable for remote assessment of cognitive function in people with multiple sclerosis (pwMS), a study published in European Journal of Neurology found.¹

Cognitive impairment is common among pwMS, with cognitive changes impacting more than half of pwMS.² Although these changes are mild in most patients, they can impact quality of life and gradually worsen as the disease progresses. Standardized neuropsychological tests are used to assess overall cognitive function or specific areas of cognitive function, with the current most recommended test and the assessment most used in clinical trials being the SDMT.¹

Typically, the SDMT is conducted in clinic and is repeated at relatively infrequent intervals of 6 to 12 months. At these intervals, fluctuations between evaluations can be missed, and the in-person nature of the test can be a limitation for patients, especially in remote areas.

The eSDMT was developed to facilitate more frequent cognitive assessments for people with multiple sclerosis. | Image credit: fizkes - stock.adobe.com

“We designed the eSDMT to enable pwMS to perform frequent remote cognitive assessments independently, promoting a shift from the conventional cross-sectional ‘healthy/impaired’ framework to an intra-individual longitudinal ‘stable/worsening’ framework,” the authors explained. “The latter greatly reduces the impact of inter-individual sensory motor differences, which may bias between-groups comparisons. The same also applies to potential confounders like sex, age, and education.” Age and education did not substantially affect eSDMT scores in this study, they noted.

The eSDMT was developed to be on demand immediately from any internet browser without downloading any software or setting up any programs. It has minimal hardware and software requirements, and has cross-platform compatibility. Instructions are displayed in writing on the screen, and there is a practice run prior to each task on the test.

A total of 62 patients underwent neuropsychological evaluation and completed the eSDMT at the clinic. Then, 42 patients completed the eSDMT at home. Main outcomes of interest were concurrent validity of the eSDMT compared with the oral SDMT, test-retest reliability in the clinic compared with at home, and discriminant validity in identifying those with and without cognitive impairment. The effect of other psychometric traits of the eSDMT, like age, sex, and education on test scores, were also explored.

The concurrent validity was good to excellent in the study, with strong correlations between the oral SDMT scores and mean reaction times on the eSDMT, as well as the correct responses in 90 seconds ([r = 0.873; P < .0001] and [r = 0.837; P < .0001], respectively).

The test-retest reliability in the study was also good to excellent for mean reaction times and correct responses in 90 seconds (intraclass correlation coefficients [ICCs] > 0.87; all P < .0001). The discriminant validity was excellent, with areas under the curve above 0.84 (P = .0001). Demographic characteristics only slightly influenced eSDMT scores (all R2 < 0.200).

The study was limited by a lack of a healthy control group, which would have allowed for assessment of discriminant validity between pwMS and healthy controls, the authors noted. Further studies are also needed to determine how effective the eSDMT is for monitoring pwMS who have atypical cognitive impairment profiles.

“In conclusion, evidence supports this eSDMT as a feasible, valid, and reliable remote tool for assessing cognitive function in pwMS. Its availability may prove invaluable for research, as it allows the collection of more data, for longer periods of time, in a cost-effective way,” the authors wrote. “These features allow large-scale decentralized data collection for longitudinal validation. From a clinical standpoint, such validation may enable clinicians to stop relying solely on infrequent clinical visits, thus providing a clearer clinical picture and allowing tailored interventions based on intra-individual longitudinal trends.”

References

1. Dini M, Gamberini G, Tacchini M, et al. Development and validation of an electronic Symbol-Digit Modalities Test for remote monitoring of people with multiple sclerosis. Eur J Neurol. Published online September 4, 2024. doi:10.1111/ene.16454

2. Cognitive changes and multiple sclerosis. National Multiple Sclerosis Society. Accessed September 12, 2024. https://www.nationalmssociety.org/understanding-ms/what-is-ms/ms-symptoms/cognitive-changes