Clinical impact of 20% worsening on Timed 25-foot Walk and 9-hole Peg Test in multiple sclerosis

Introduction: Quantitative tests of motor function, like the Timed 25-foot Walk (T25FW) and 9-hole Peg Test (9HPT), are increasingly being applied as outcome measures in multiple sclerosis (MS) clinical trials. The quantitative nature of the data has a favorable impact on responsiveness, but the clinical impact of the changes is uncertain. The goal of this study was to assess whether a change on T25FW and 9HPT does indeed have a clinical meaning. This was accomplished by comparing 20% changes on these quantitative measurements to concomitant changes on the Guy's Neurological Disability Scale (GNDS), a scale which measures patient-perceived daily life disability. Methods: From a longitudinal database, we selected patients with at least two measurements of T25FW, 9HPT and GNDS with a minimal time interval of 350 days. In those patients who experienced at least a 20% change on T25FW or 9HPT, GNDS score changes were examined more closely. Results: Of 527 patients, 143 experienced a > 20% worsening on their T25FW and 71 on their 9HPT, respectively. Patients with a 20% increase in T25FW or 9HPT had more GNDS worsening than patients without such an increase. GNDS worsening associated with an increase in T25FW was mainly due to an increase in perceived disability related to lower extremity function and fatigue; GNDS worsening associated with an increase in 9HPT was more diffuse with respect to domains involved. Conclusion: Worsening on T25FW or 9HPT has a clinical impact on disability, as perceived by MS patients during daily life functioning.