Validity of Scores From the 12-Item Multiple Sclerosis Walking Scale Among Young, Middle-Aged, and Older Adults With Multiple Sclerosis

OBJECTIVE: To examine the construct validity of inferences from scores on the 12-item multiple sclerosis walking scale (MSWS-12) as a patient-reported outcome measure of walking dysfunction among young, middle-aged, and older adults with multiple sclerosis (MS). DESIGN: Cross-sectional, comparative research design. SETTING: University research laboratory. PARTICIPANTS: The sample included 187 participants (N=187) with MS who were categorized into young (20-39y, n=50), middle-aged (40-59y, n=83), and older (60-79y, n=54) adult age groups. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The participants completed the MSWS-12; the timed 25-foot walk, 6-minute walk, and timed Up and Go; and the Brief International Cognitive Assessment for MS. The data analyses were performed using IBM SPSS Version 29.0.2.0 for the iOS platform. RESULTS: There were similar patterns of linear worsening of scores for the MSWS-12 (F1,187=12.7, P<.001, η²=0.07), timed 25-foot walk (F1,187=11.5, P<.001, η²=0.06), 6-minute walk (F1,187=13.1, P<.001, η²=0.08), and timed Up and Go (F1,184=10.8, P<.001, η²=0.06) across the 3 age groups. MSWS-12 scores had strong partial correlations with timed 25-foot walk, 6-minute walk, and timed Up and Go in the overall sample (partial r's of 0.59, 0.66, 0.55, respectively) and across the 3 age groups, when controlling for Brief International Cognitive Assessment for MS outcomes. CONCLUSIONS: We provide new evidence for the construct validity of MSWS-12 scores as a patient-reported outcome measure of walking dysfunction across the adult lifespan in MS. Our results, in particular, support the application of the MSWS-12 in clinical research and practice involving older adults with MS who experience the combined effects of advanced age and MS disease progression.