Estimating the association between physical activity and health-related quality of life in individuals with multiple sclerosis.

Background: Higher levels of total physical activity (PA) are associated with better health-related quality of life (HRQOL) in individuals with multiple sclerosis (MS). The benefits of PA across the activity continuum have not been well-studied. The goal of this study was to compare the associations between total PA, strenuous PA, moderate PA, and mild PA and HRQOL in a large cohort of individuals with MS using both generic and neurologic disease-specific questionnaires. Longitudinal changes in PA and HRQOL over two years were also examined METHODS: Subjects enrolled in SysteMS completed the Godin Leisure Time Exercise Questionnaire (GLTEQ) to measure PA. Subjects also completed generic (SF-36) and neurologic disease-specific (NeuroQoL) HRQOL measures. GLTEQ and HRQOL measures were administered at baseline and 24 months. The associations between the GLTEQ total leisure activity (TLA), strenuous PA, moderate PA and mild PA and scores on NeuroQoL and SF-36 were estimated using Spearman's correlation coefficient and partial Spearman's correlation coefficient adjusting for age, sex and Expanded Disability Status Scale (EDSS) measured by a provider. To further investigate the associations between mild PA and HRQOL measures, the associations between mild PA and HRQOL were estimated in participants who reported no moderate or strenuous PA in the last week. The changes in GLTEQ TLA scores and each component score were compared to the changes in NeuroQoL and SF-36 over 24 months using Spearman's correlation coefficient and partial Spearman's correlation coefficient adjusting for age, sex and EDSS.

Results: Statistically significant weak correlations were observed between GLTEQ TLA and NeuroQoL and SF-36 domains, with higher levels of TLA being associated with better HRQOL outcomes. After adjusting for age, sex and EDSS, all correlations were attenuated. Strenuous and moderate levels of PA were similarly associated with many HRQOL outcomes, but mild PA was only weakly correlated with NeuroQoL Lower Extremity Function. There was limited change in PA over 24 months. In a subgroup of participants who reported mild PA, but no moderate or strenuous PA, there were no significant associations with NeuroQoL or SF-36 domains at baseline, but increases in mild PA over two years were moderately associated with improvement on NeuroQoL Upper Extremity Function and SF-36 Mental Health and Mental Component Summary.

Conclusion: There were weak associations between TLA and HRQOL across a wide range of HRQOL variables. In addition, both strenuous PA and moderate PA were weakly associated with many HRQOL outcomes, but mild PA was only associated with lower extremity function. Increases in mild PA in a subgroup of individuals who reported no strenuous or moderate PA at baseline were associated with improvements in HRQOL at 24 months. These findings suggest that programs aimed at increasing PA across the activity continuum may lead to improvements in multiple areas of HRQOL in individuals with MS.