A team of researchers published results of a study of the Symbol Digit Modalities Test (SDMT), a measure widely used for cognitive assessment in research and clinical settings. Their article,” A much needed metric: Defining reliable and statistically meaningful change of the oral version Symbol Digit Modalities Test,” (10.1016/j.msard.2021.103405) was published online in Multiple Sclerosis and Related Disorders on November 16. 2021. The authors represent four study sites: Kessler Foundation, Pennsylvania State University, University of Missouri-Kansas City, and University of Washington.

Despite agreement on what constitutes group-level change for the SDMT (4 points), studies of what constitutes meaningful change on the individual level are lacking. To help address this gap, 219 healthy adults were enrolled in the multi-site trial and followed up at 6 months and one year. Results showed reliable change scores of 7 to 9 points at 6 months, and 8 to 12 points at one year. These findings indicate the need for higher cut points for the SDMT on the individual level, suggesting that a change score of 8 would be the recommended cut off at 6 months and one year,

Defining statistically significant change in the SDMT is critical, according to lead author Lauren Strober, PhD, senior research scientist in the Center for Neuropsychology and Neuroscience at Kessler Foundation. “In the population with multiple sclerosis, the SDMT is used to measure deficits in processing speed,” noted Dr. Strober, “which we know adversely affect functional independence, activities of daily living, and overall quality of life. Standardizing normative data for this tool will help us more accurately assess changes over time for each person” she added, “This will enable is to better predict disease progression and improve outcomes for individuals in terms of employment, driving, and activities of daily living.”