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

This study is to evaluate swallowing problems (dysphasia) in multiple sclerosis (MS) patients; the importance of using tools that are durable and appropriate is well understood. One of the most trusted tools is the dysphagia in multiple sclerosis (DYMUS) test. The aim of this study was to prepare a Persian version and to evaluate the validity and reliability of the test. This methodological study was conducted on 236 MS patients in Southeast of Iran from August 2015 to February 2016. After translation and cultural adaptation of the test in Persian, the validity of this test was determined using expert opinions accordance with the International Quality of Life Assessment Project. In addition, exploratory factor analysis (EFA) was performed with varimax rotation. The confirmatory factor analysis (CFA) was conducted and the goodness of fit indices was calculated. Moreover, to test the reliability, Cronbach’s alpha coefficient and intraclass correlation coefficient (ICC) were used. In total, 236 MS patients were included in the study (81 males and 155 females). All the questions in the test’s Persian version obtained an acceptable face and content validity (content validity ratio = 1, Scale content validity index/Ave = 1). EFA revealed that the scale has two factors (solid–liquid) with 67.5% cumulative variance. CFA indicated a good fit to the intended two‑factor structure, and the ratio of Chi‑square to the degree of freedom was 1.79, and the root mean square error of approximation was 0.058. The internal consistency of total test indicated the appropriate level (Cronbach’s alpha coefficient = 0.775), and test–retest reliability total questionnaire was found to be ICC = 0.985, indicating its high reliability. The results of this study indicated that the Persian version of the DYMUS questionnaire had good reliability and validity for patients with MS.