A new analysis has reported that significant worsening on the Timed 25-Foot Walk (T25FW) is predictive of EDSS progression in a majority of MS cases (Kalinowski et al. Mult Scler 2021; epublished June 8, 2021). Confirmed disability progression (CDP) was defined as >20% change from baseline in T25FW sustained for >90 days.
The analysis was based on data for placebo patients from nine clinical trials included in the MS Outcomes Assessment Consortium (MSOAC) trial database (N=2382). Mean age was 41.8 years; mean disease duration was 6.1 years; 64.1% were RRMS, 22.4% were SPMS and 13.5% were PPMS; and mean baseline EDSS score was 3.36.
At baseline, the mean T25FW times (and walking speeds) varied considerably by age: 6.0 seconds (5.0 ft/sec) in the age 18-30 years age group; 7.4 seconds (4.5 ft/sec) in the age 30-40 group; 9.4 seconds (3.9 ft/sec) in the age 40-50 group; 12.5 seconds (3.2 ft/sec) in the age 50-60 group; and 15.2 seconds (2.6 ft/sec) in the age >60 group. The average T25FW time was 9.2 seconds for the full cohort.
There was no significant difference in walking times between women and men. However, there was a significant difference between MS phenotypes with respect to the annualized increases (0.6 for RRMS, 4.9 for SPMS), suggesting that significant changes in T25FW times may herald the onset of SPMS.
The study made several interesting observations. The T25FW time at baseline appeared to be predictive of disability: patients with a baseline time >6 seconds had a faster rate of T25FW worsening. Secondly, there was not a strong association between T25FW and the number of relapses, in contrast to what has been reported in previous studies (Kaufman et al. Mult Scler 2000;6:286-290).
Thirdly, T25FW progression preceded EDSS progression in 65% of cases overall. In the subgroup of patients with EDSS >4.0 and both T25FW and EDSS progression, worsening T25FW preceded EDSS worsening in 72% of cases. These findings suggest that T25FW may provide an earlier indication of disability progression than EDSS and may be a useful substitute if EDSS is not being routinely evaluated in practice.