Naturally-Occurring Change in Multiple Sclerosis Walking Scale-12 Scores over Time in Relapsing-Remitting Multiple Sclerosis

Background: The impairment of walking is one of the most common and burdensome features of multiple sclerosis (MS), yet there is little information about the trajectory and pattern of naturally-occurring changes over time.

Objectives: This study involved an analysis of the trajectory and pattern of change in perceived walking impairment over a 30-month period in persons with relapsing-remitting MS (RRMS).

Methods: 269 persons with RRMS completed the 12-item Multiple Sclerosis Walking Scale (MSWS-12) every 6 months over a 30-month period. Data were analyzed using latent growth curve modeling (LGM) and latent class growth curve modeling (LCGM) in Mplus 7.0.

Results: LGM demonstrated that a linear trajectory adequately described the pattern of change in MSWS-12 scores over time (χ²=33.28, p<.05, CFI=.99, SRMR=.03). Overall, there was a linear increase in MSWS-12 scores over time (M_s=0.5, p<.05), and significant variance around the trajectory of group mean change (V_s=8.7, p<.05). LCGM identified a three-class model for changes in MSWS-12 scores over time. Class I involved moderate initial status (i.e., moderate levels of walking impairment) and a large linear increase over time (i.e., worsening walking impairment). Class II involved high initial status (i.e., severe levels of walking impairment), but no change over time (i.e., stable levels of severe walking impairment). Class III involved low initial status (i.e., low levels of walking impairment) and a small linear decrease over time (i.e., improving walking impairment).

Conclusions: Walking impairment changes over time in RRMS, and this can be described by three patterns of change trajectories that differed based on initial status of self-reported walking impairment.