Mobility trajectories in multiple sclerosis: A comparative study of timed 25-foot walk and a patient-reported outcome measure

Abstract

Background: Loss of mobility is common in persons with multiple sclerosis (PwMS), but little is known about this impairment from the patient’s perspective. Objective: The aim is to model longitudinal variation in a mobility patient-reported outcome (PRO) and compare trajectories to those observed for Timed 25-Foot Walk (T25FW) in a retrospective cohort. Methods: Latent-class growth analysis was applied to 47,508 measures of Performance Scales© Mobility PRO (PS-Mobility) over ~4 years for 8524 PwMS. For 7347 PwMS, there were 41,988 T25FW measures during this period. Repeated measures correlation and concordance of trajectory assignment were evaluated. Results: At the group level, PS-Mobility and T25FW linearly worsened and repeated-measures correlation was moderate. Eight latent classes with varying shapes that worsened described PS-Mobility variation, compared to six latent classes for T25FW that differed by intercept. The agreement between PS-Mobility and T25FW cluster assignment was modest. A higher proportion of individuals who were Black/African American, older, Medicaid beneficiaries, living in deprived neighborhoods, had longer disease duration, had progressive disease, and ever smokers were assigned to more impaired clusters. Discussion: Cross-sectionally, PS-Mobility and T25FW were highly correlated, but longitudinally correlation was modest to moderate, underscoring the importance of considering both objective and subjective perspectives in evaluating mobility changes in PwMS.