Is the Symbol Digit Modalities Test a useful outcome in secondary progressive multiple sclerosis?
European journal of neurology : the official journal of the European Federation of Neurological Societies
washington; seattle; swedish neuro
BACKGROUND: It is unclear which cognitive outcome measure is the most useful for clinical trials in multiple sclerosis. To investigate the usefulness of the Symbol Digit Modalities Test (SDMT) as a clinical outcome measure in secondary progressive multiple sclerosis (SPMS), we describe the frequency of worsening and improvement events in a large randomized controlled trial (RCT) dataset.
METHODS: Using original trial data from the ASCEND trial (n = 889), a recent large RCT in SPMS, we describe worsening and similarly defined improvement with and without 3-month confirmation on the SDMT in the whole trial cohort and unconfirmed worsening and improvement on the Paced Auditory Serial Addition Test (PASAT) in a smaller subset (n = 107).
RESULTS: Somewhat unexpectedly, SDMT scores steadily increased throughout the 2 years of follow-up in this trial. There were overall few SDMT worsening events throughout the trial (generally fewer than 10% of participants), but improvement events steadily increased from around 50% of participants with improvement at 12 weeks to more than 70% at 84 weeks and beyond. PASAT scores followed a similar pattern.
CONCLUSIONS: In this well-characterized clinical trial cohort, the SDMT does not reflect the steady cognitive decline that patients with SPMS experience. Both SDMT and PASAT scores improve throughout follow-up, possibly due to a practice effect. The SDMT may not be a useful outcome measure of disease progression in 2-year clinical trials in SPMS.
Neurosciences (Brain & Spine)
Koch, Marcus W; Mostert, Jop; Repovic, P; Bowen, J D; Uitdehaag, Bernard; and Cutter, Gary, "Is the Symbol Digit Modalities Test a useful outcome in secondary progressive multiple sclerosis?" (2021). Articles, Abstracts, and Reports. 4284.