Japanese translation and validation of the 12-item Multiple Sclerosis Walking Scale version 2.

ABSTRACT

BACKGROUND: Disability in ambulation has a critical impact on activities of daily living in patients with multiple sclerosis (MS). The 12-item Multiple Sclerosis Walking Scale (MSWS-12) is a self-reported instrument developed to assess the impact of MS on walking. The scale's 12 items assess various aspects of walking-related tasks during the past 2 weeks. MSWS-12 has been used in multiple clinical studies and translated into several languages. In the present study, we translated the MSWS-12 into Japanese and evaluated its psychometric properties in a cross-sectional study. METHODS: The original English MSWS-12 version 2 (v2) was translated into Japanese through a standard procedure. Sixty consecutive Japanese MS patients completed the newly prepared Japanese MSWS-12v2 questionnaire and repeated the test 14 days later. Physical disability was assessed by the Expanded Disability Status Scale (EDSS), Timed 25-foot Walk (T25FW), and 9-hole Peg Test (9HPT). Cognitive performance was evaluated using the Processing Speed Test (PST). Fatigue and health-related quality of life were assessed using the Japanese versions of the Fatigue Severity Scale (FSS) and the Functional Assessment of MS (FAMS). RESULTS: The mean age of the patients was 42.5 years, with median disease duration of 10 years, and median EDSS of 2.0 (range 0, 6.5). Forty-seven patients (78.3 %) had relapsing-remitting, 9 (15.0 %) had secondary-progressive, and 4 (6.7 %) had primary-progressive phenotypes. The median score of the MSWS-12v2 was 5.95 (interquartile range 0, 50.6). Twenty-seven patients (45 %) scored the lowest possible score (0 points), while one (1.7 %) scored the highest possible score (100 points). Cronbach's alpha was 0.98 (95 % confidence interval [CI] 0.97, 0.98), and the test-retest intraclass correlation was 0.95 (95%CI 0.94, 0.96). MSWS-12v2 score was strongly correlated with EDSS (Spearman's ρ = 0.73 [95%CI 0.58, 0.83]), T25FW (ρ = 0.70 [95%CI 0.55, 0.81]), and total FAMS score (ρ = -0.80 [95%CI -0.88, -0.69]), and moderately correlated with 9HPT (ρ = 0.65 [95%CI 0.47, 0.77] for the dominant hand; ρ = 0.62 [95%CI 0.43, 0.75] for the non-dominant hand), PST (ρ = -0.65 [95%CI -0.78, -0.47]), and FSS (ρ = 0.68 [95%CI 0.52, 0.80]). Among the subcomponents of FAMS, the mobility subcomponent showed the most robust correlation with MSWS-12v2 score (ρ = -0.91 [95%CI -0.94, -0.81]). In patients with minimal or no objective disability (EDSS < 3.0, n = 40), only the mobility subcomponent of FAMS was strongly correlated with MSWS-12v2 score (ρ = -0.76 [95% CI -0.87, -0.58]). In contrast, correlations of MSWS-12v2 score with EDSS and T25FW were weak in this subgroup (ρ = 0.28 [95%CI -0.03, 0.55] for EDSS; ρ = 0.25 [95%CI -0.06, 0.52] for T25FW). Response patterns for the single items showed that 32.5 % of the patients with EDSS below 3.0 reported having problems with balance, followed by climbing stairs and standing while doing things (both 25 %). CONCLUSION: The Japanese version of the MSWS-12v2 developed in this study is reliable, valid, and helpful for screening walking disability in Japanese MS patients, including those with minimal objective disability.