Longitudinal analysis of physical activity and symptoms as predictors of change in functional limitations and...

This longitudinal, observational study examined changes in physical activity and symptoms as correlates of changes in functional limitations and disability across a 6-month period among individuals with multiple sclerosis (MS).

Individuals with MS wore an accelerometer for a 7-day period and completed a battery of measures including the Godin Leisure-Time Exercise Questionnaire (Godin & Shephard, 1985), Symptom Inventory (Schwartz, Vollmer, & Lee, 1999), MS-Related Symptom Checklist (Gulick, 1989), and abbreviated Late-Life Function and Disability Inventory (McAuley, Konopack, Motl, Rosengren, & Morris, 2005) at baseline (n = 292) and 6-month follow-up (n = 276). The data were analyzed using panel analysis with latent variables in AMOS 16.0.

The standardized coefficients indicated that (a) change in physical activity was associated with residual change in function (beta = .22), (b) change in symptoms was associated with residual changes in both function (beta = -.29) and disability (gamma = -.15), and (c) change in function was associated with residual change in disability (beta = .20).

Our findings indicate that change in physical activity is associated with change in disability through a pathway that is consistent with Nagi's (1976) Disablement Model and its extension in individuals with MS.