Revealing the clinical significance of PASAT rejection in multiple sclerosis: Insights from patient-reported and clinician-assessed outcomes

Background: The Paced Auditory Serial Addition Test (PASAT) is widely used to assess cognitive functioning and fatigability in people with Multiple Sclerosis (PwMS). However, its poor acceptability and high refusal rates may limit its clinical interpretability, while potentially conveying meaningful information beyond test performance. Objectives: To determine whether PASAT rejection at the first assessment represents a clinically meaningful marker of overall vulnerability in PwMS, reflected by a tendency toward worsening across demographic, disease-related and clinical domains, using both patient-reported and clinician-assessed outcomes. Methods: One-way ANOVAs or non-parametric equivalents were run to compare different groups defined by baseline PASAT performance (missing, low, high) in terms of demographic, disease-related and clinical variables. Results: Retrospective data from 1154 PwMS were analyzed. Participants with missing PASAT (N=224) were significantly older (60.1±13.5 years), had longer disease duration (18.9±12.2 years), higher EDSS (6.1±2.0), lower educational level (9.9±3.9 years), poorer cognitive performances on the Montreal Cognitive Assessment (MoCA) and Symbol Digit Modalities Test (SDMT) (respectively, 17.4±6.5, 22.5±13.6), and higher level of required assistance in daily functioning as measured by the Functional Independence Measure (FIM) (91.1±29.3), compared with both low and high PASAT groups (all ps < 0.05). Conclusions: PASAT rejection at first assessment identifies a subgroup of older PwMS with higher disability, lower education, and more pronounced cognitive and functional impairments, suggesting that test refusal may serve as a clinically relevant marker of overall vulnerability in MS.