Long-term trajectories of ambulatory impairment in multiple sclerosis.

backgroundAmbulatory impairment is a common and complex manifestation of multiple sclerosis (MS), and longitudinal patterns are not well understood.

objectiveTo characterize longitudinal walking speed trajectories in a general MS patient population and in those with early disease (⩽ 5 years from onset), identify subgroups with similar patterns, and examine associations with individual attributes.

methodsUsing a retrospective cohort study design, latent class growth analysis was applied to longitudinal timed 25-foot walk (T25-FW) data from 7683 MS patients, to determine T25-FW trajectories. Associations were evaluated between trajectory assignment and individual attributes. Analyses were repeated for 2591 patients with early disease.

resultsIn the general patient population, six trajectories were discerned, ranging from very minimal to very high impairment at baseline, with variability in impairment accrual. The clusters with moderate to very high walking impairment were associated with being female, older and Black American, longer symptom duration, progressive course, and depressive symptoms. In the early disease subset, eight trajectories were discerned that included two subgroups that rapidly accrued impairment.

conclusionWe identified novel subgroups of MS patients will distinct long-term T25-FW trajectories. These results underscore that socially disadvantaged and economically marginalized MS patients are the most vulnerable for severe ambulatory impairment.