Background: People with multiple sclerosis (MS) experience symptoms in multiple domains. High-quality patient-reported outcomes (PROs) that assess multiple domains can aid healthcare providers in assessing these symptoms and may support remote disease monitoring. The "SymptoMScreen" PRO correlates with other PROs in MS; however, whether the SymptoMScreen or its component domains are associated with performance-based or clinician-assessed outcomes is unknown.
Objectives: To validate SymptoMScreen and its domains against performance-based, clinician-assessed measures or other well-validated diagnostic tools.
Methods: We recruited participants with MS from a large tertiary care center. At routine clinic visits participants completed the MS performance test (MSPT), which is an iPad-based application that objectively assesses walking speed, manual dexterity, processing speed, and low contrast letter acuity. Expanded Disability Status Scale (EDSS) scores were assessed in a subset. Participants also completed an online SymptoMScreen following clinic visits. We assessed criterion and construct validity by calculating Spearman rank correlations between the 12 SymptoMScreen domains and respective clinical outcomes. We evaluated test-retest reliability using intra-class correlation coefficients [ICC], and internal consistency reliability using Cronbach's alpha.
Results: The 102 participants were predominantly female (78%), of average age [standard deviation]: 47.6 [12.3] years, with an average disease duration: 13.1 [10.0] years); 60 participants completed the SymptoMScreen and EDSS. Composite SymptoMScreen scores were associated with EDSS (r = 0.71; 95% CI 0.54, 0.83). For individual domains, strong correlations were observed between mobility scores and walking speed (r = 0.63; 95% CI: 0.48, 0.75) and hand function scores with manual dexterity (r = 0.52; 95% CI: 0.36, 0.65). More moderate correlations were detected for the cognition domain with processing speed (r=-0.37; 95% CI: -0.53, -0.18) and for the visual function domain with low contrast letter acuity at 2.5% contrast (r=-0.33; 95% CI -0.54, -0.08). Both test-retest and internal consistency reliability measures for overall SymptoMScreen scores were high (ICC: 0.88; 95% CI: 0.80, 0.93; Cronbach's alpha: 0.93; 95% CI: 0.90, 96).
Conclusions: The SymptoMScreen is practical outcome measure whose subscales may provide a valid assessment of corresponding performance-based and clinician-assessed measures among people with MS with mild-to-moderate disability.
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