Cognitive impairment (CI) is a remarkable feature in pediatric-onset multiple sclerosis (POMS). The Symbol Digit Modalities Test (SDMT) is increasingly used to explore CI in MS. Recently, a four-point worsening on the SDMT score has been demonstrated to correlate with a clinically meaningful cognitive worsening in adult MS. We conducted a post hoc analysis of a randomized computer-assisted rehabilitation trial for attention impairment in POMS to test the clinical meaningfulness of the changes in SDMT scores at the end of the trial (delta SDMT). A four-point SDMT cut-off was applied. POMS patients exposed to specific computer training (ST) and non-specific training (nST) were compared. Data of 16 POMS (9 females, age 15.75 ± 1.74 years) patients were analyzed. At the end of the trial, 25% of patients reported no clinically significant changes (-3 to 3), 12.5% a clinically significant worsening (≤-4) and 62.5% a clinically significant improvement (≥4) in the delta SDMT. The proportion of patients reporting a clinically meaningful improvement was significantly (p = 0.008) higher (100%) in patients exposed to ST in comparison to those (25%) exposed to nST. The use of the four-point SDMT cut-off may be useful to assess the clinical meaningfulness of results from cognitive rehabilitation trials.
Keywords: Symbol Digit Modalities Test; attention; cognitive impairment; pediatric multiple sclerosis; rehabilitation.