Validation of the Persian version of dysphagia in multiple sclerosis questionnaire for the assessment of dysphagia in multiple sclerosis

Background: About one third of patients with multiple sclerosis (MS) experience dysphagia. Dysphagia can cause complications such as malnutrition, lung infections, aspiration pneumonia and dehydration, thus it is very helpful to diagnose dysphagia as soon as possible. The aim in this study was to translate dysphagia in multiple sclerosis (DYMUS) questionnaire into Farsi and and validate it. Methods: Forward-backward method was used to translate original English version of DYMUS into farsi, and then the questionnaire (one for each patient) was filled in through asking questions from 200 patients with MS by a speech and language pathologist. Confirmatory factor analysis (CFA) was used to examine the construct validity. Internal consistency and test-retest reliability of the DYMUS were evaluated using Cronbach's alpha and the intraclass correlation coefficient (ICC), respectively. Results: CFA showed that a two-factor model of DYMUS including "dysphagia for solid" and "dysphagia for liquid" fitted the data well [relative chi-square [chi(2)/degree of freedom (df) = 1.55, CFI = 0.967, Tucker-Lewis index (TLI) = 0.957, root mean square error of approximation (RMSEA) = 0.053, and weighted root mean square residual (WRMR) = 0.8741. The Cronbach's alpha for total score and liquid and solid subscales were 0.776, 0.557, and 0.725, respectively. The DYMUS showed adequate test-retest reliability for the total and subscales (ICC: 0.880-0.956). Moreover, this study has shown a significant relationship between DYMUS score and Expanded Disability Status Scale (EDSS) score, disease duration, type of MS, and self-reported dysphagia. Conclusion: The Persian version of DYMUS is a reliable and valid tool to screen dysphagia among patients with MS.