A 25-foot timed walk (T25FW) and 9-hole peg test (9HPT) may be more reliable clinical outcome measures than the Extended Disability Status Scale (EDSS) in patients with secondary progressive multiple sclerosis (SPMS), according to published study results in neurology.
There is limited data on the reliability of clinical outcome measures beyond EDSS in patients with SPMS. The aim of this study was to evaluate the reliability of clinical results in SPMS studies using data from the placebo arms of two randomized, controlled studies.
Both IMPACT and ASCEND were randomized, double-blind, placebo-controlled studies evaluating treatment with interferon beta 1a or natalizumab in patients with SPMS. Disability progression and rates of improvement were assessed by comparing baseline and follow-up disability measures. They were defined as a deterioration or improvement of at least 20 percent from baseline for the T25FW and 9HPT. A deterioration or “improvement” in the EDSS was defined as an increase or decrease of 1 whole point on the EDSS if the base EDSS was 5.5 or less, and 0.5 points if the base EDSS was 6, Was 0 or 6.5. A progression event was classified as persistent if it was confirmed after 3 months and on the last visit.
According to data from 219 patients from the IMPACT data set and 449 patients from the ASCEND data set, the disability increased steadily over time for each measure. In both data sets, the EDSS showed the highest rates of improvement over time. In addition, it showed the smallest difference between rates of improvement and disability progression.
Disability progression rates for T25FW and 9HPT increased steadily throughout the study. The “improvement rates” for both were no more than 10%. For the EDSS, the rates of improvement increased in line with the rate of progression in disability throughout the study. This difference was more pronounced in the IMPACT data set than in the ASCEND data set.
“All of the outcome measures examined in SPMS showed some evidence of random variations and measurement errors, T25FW and 9HPT less than the more established EDSS outcome,” concluded the study researchers.
Koch MW, Mostert J., Repovic P., Bowen JD, Uitdehaag B., Cutter G. Reliability of outcome measurements in clinical trials in secondary progressive multiple sclerosis. Neurology. Published online October 26, 2020. doi: 10.1212 / WNL.0000000000011123