Performed and perceived walking ability in relation to the Expanded Disability Status Scale in persons with multiple sclerosis

Background: The severity of walking impairment in persons with multiple sclerosis (pwMS) at different levels on the expanded disability status scale (EDSS) is unclear. Furthermore, it is unclear if the EDSS is differently related to performed- and perceived walking capacity tests. Aims: To quantify walking impairment and perceived impact of MS on walking according to EDSS scores and to examine the relations between these parameters in pwMS. Methods: EDSS was collected by neurologists and walking was assessed by the timed 25 ft walk test (T25FWT), two minute walk test (2MWT), six minute walk test (6MWT) and the 12-item MS walking scale (MSWS-12) in 474 PwMS with mild (EDSS 1-4: n = 200) to moderate (EDSS 4.5-6.5: n = 274) MS. Magnitude of walking impairment was calculated and related to EDSS. Results: Compared to predicted values in healthy controls, walking speed was reduced by 41.5 +/- 25.8% in the 6MWT for the total MS group and by 21.8 +/- 20.2% and 55.8 +/- 19.1% in the mild and moderate MS subgroups, respectively. The EDSS score showed the strongest relationship to the 2MWT and the 6MWT in the total MS group (r = -0.76, p < 0.0001), to the MSWS-12 score in the mild MS group (r = 0.56, p < 0.0001), and to the 2MWT in the moderate MS group (r = -0.50, p < 0.0001). Conclusion: In pwMS (EDSS scores 1-6.5), walking speed is on average reduced by similar to 40% when compared to predicted values in healthy controls, and impairments are already present at early disease stages, suggesting early initiation of rehabilitation. The 2MWT and 6MWT show the strongest relationship to EDSS, but the MSWS-12 identify impairments more gradually at low EDSS scores.