OBJECTIVES: The systematic assessment of patient´s perspective may provide valuable information to facilitate shared-decision making in multiple sclerosis (MS) care. The SymptoMScreen is a brief self-report tool for measuring symptom severity in twelve neurologic domains commonly affected by MS: walking, hand function/dexterity, pain, spasticity, fatigue, bladder function, sensory, vision, dizziness, cognition, depression, and anxiety. Limited information is available on its dimensionality and item characteristics. The aim of the study was to assess the psychometric characteristics of the SymptoMScreen in the management of MS.

METHODS: A multicenter, cross-sectional study in patients with relapsing-remitting MS (McDonald 2010 criteria) was conducted in sixteen MS units in Spain. A non-parametric item response theory procedure, Mokken analysis, was performed to assess the underlying dimensional structure and scalability of items and overall questionnaire. Parametric Samejima’s Grade Response Model (GRM) was applied to assess the items’ discrimination and information. All analyses were performed with R (v 3.6.0) using the libraries mokken and ltm.

RESULTS: A total of 218 patients were studied (mean age: 39.1 ± 9.5 years, 70.6% female, median EDSS score: 2 [IQR 1, 4]). Symptom severity was low (median SymptoMScreen score: 13.5, IQR 4.2, 27). Fatigue was the domain with the highest score. The questionnaire showed a good reliability (Cronbach’s alpha: 0.94, 95% bootstrap CI: 0.93 to 0.95) and all their twelve measurement domains fitted a unidimensional-underlying construct according to Mokken analysis. All item-scalability coefficients were greater than 0.50, whereas the scalability of the overall questionnaire was 0.60 agreeing with a strong scale. The item characteristic curves from GRM showed adequate probability patterns for response categories with an item-ranking order for discrimination that also agreed with the observed order for item information.

CONCLUSIONS: The SymptoMScreen shows appropriate psychometric characteristics and therefore is a useful instrument for the rapid assessment of MS symptoms in clinical practice.