Are Changes in Gait and Balance Across the Disease Step Rating Scale in Multiple Sclerosis Statistically Significant and Clinically Meaningful?

OBJECTIVES: To explore differences in gait endurance, speed, and standing balance in people with multiple sclerosis (MS) across the Disease Step Rating Scale, and to determine if differences are statistically significant and clinically meaningful. DESIGN: Observational study. SETTING: Community rehabilitation - primary health care center. PARTICIPANTS: Community-dwelling people with MS (N=222; mean age, 48±12y; 32% men). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Participants were categorized using the Disease Step Rating Scale. Demographics and clinical measures of gait endurance (6-minute walk test [6MWT]), gait speed (10-m walk test [10MWT] and 25-foot walk test [25FWT]), and balance (Berg Balance Scale [BBS]) were recorded in 1 session. Differences in these parameters across categories of the Disease Step Rating Scale were explored, and clinically meaningful differences were identified. RESULTS: The 6MWT showed a greater number of significant differences across adjacent disease steps in those with less disability (P<.001), whereas the 10MWT and 25FWT demonstrated more significant changes in those with greater disability (P<.001). The BBS demonstrated significant differences across the span of the Disease Step Rating Scale categories (P<.001). Differences in gait and balance between adjacent Disease Step Rating Scale categories met most previously established levels of minimally detectable change and all minimally important change scores. CONCLUSIONS: Our findings support the Disease Step Rating Scale is an observational tool that can be used by health professionals to categorize people with MS, with the categories reflective of statistically significant and clinically meaningful differences in gait and balance performance.