Symptomatic correlates of six-minute walk performance in persons with multiple sclerosis

Background. The six-minute walk (6MW) test has been identified as a valid, reliable, and reproducible measure of endurance walking performance that differentiates persons with multiple sclerosis (MS) and controls and correlates with disability and walking impairment. Aim. This study examined symptoms of fatigue, pain, and depression as correlates of 6MW performance and the possibility that such symptoms would account for the difference in 6MW distance between persons with MS and controls. Design. Observational. Setting. Research laboratory Population. Sixty-six persons, 33 with MS and 33 controls matched on age, sex, height, and weight. Methods. Participants completed the Fatigue Severity Scale (FSS), Short-Form of the McGill Pain Questionnaire (SF-MPQ), and depression items of the Hospital Anxiety and Depression Scale (HADS-D) and then performed the six-minute walk (6MW) in a rectangular corridor. Results. There were statistically significant differences between groups in 6MW distance (p = 0.0001) and FSS (P=0.0001) and SF-MPQ (P=0.025), but not HADS-D (P>0.05), scores. 6MW distance was significantly correlated with FSS (P=-0.66), SF-MPQ (P=-0.38), and HADS-D (P=-0.33) scores in the overall sample, but 6MW distance was significantly correlated with only FSS scores in the separate samples of those with MS (P=-0.46) and controls (P=-0.46). Only group (beta=0.32) and FSS scores (beta=-0.53) explained variance in overall 6MW distance in a hierarchical, linear regression analysis. Conclusion. This study provides new insight into the symptomatic correlates of 6MW performance and identifies fatigue as a possible target of interventions designed to improve walking endurance in MS. Clinical Rehabilitation Impact. Clinicians and practitioners might consider targeting fatigue as a method of managing compromised endurance walking in persons with MS.