Day-to-day variability of maximum walking distance in MS patients can mislead to relevant changes in the Expanded Disability Status Scale (EDSS): average walking speed is a more constant parameter

In this preliminary study we measured maximum walking distance and walking time on four consecutive days in 29 patients with clinically stable multiple sclerosis (MS). Patients were included in the study if they could achieve a maximum unaided walking distance of 100 up to 500 m. Our results showed a certain day-to-day variability of maximum walking distance, in some cases meaning changes up to 1.5 points in the expanded disability status scale (EDSS), which could be misinterpreted as a progression of the disease. Simultaneous measurements of maximum walking time showed a similar variability, unlike the mean walking speed which turned out to be more stable. Our results therefore suggest that scoring of MS patients should not be based on one single measurement of the maximum walking distance. The more reliable parameter appears to be the mean walking speed.