Multiple Sclerosis Walking Scale-12 and oxygen cost of walking

Background: The 12-item multiple sclerosis walking scale (MSWS-12) has been validated against self-report and clinical markers, but has not been validated with a physiological marker of locomotor impairment. Objective: This study further validates the MSWS-12 based on its correlation with the oxygen cost (O₂ cost) of walking as a physiological marker of locomotor impairment in persons with multiple sclerosis (MS). Methods: Participants (N=24) with MS completed the MSWS-12 and then wore a portable metabolic unit for measuring the O₂ cost of walking during three 6-min walk (6MW) tests. The first 6MW test involved the participant's comfortable walking speed (CWS), whereas the second and third 6MW tests were undertaken above (faster walking speed, FWS) and below (slower walking speed, SWS) the participant's CWS (i.e., ±5mph CWS). Results: MSWS-12 scores correlated strongly with O₂ cost of walking during the 6MW tests undertaken at CWS (r=641, p=001), FWS (r=616, p=001), and SWS (r=639, p=001). Interpretation: We provide evidence that further confirms the validity of the MSWS-12 as a measure of the impact of MS on walking.