Fatigue in multiple sclerosis: associations with health-related quality of life and physical performance

Background and purpose: Fatigue is a common, but still one of the least understood symptoms in multiple sclerosis (MS). We aimed to investigate whether fatigue was associated with demographic-, clinical-, health-related quality of life (HRQoL)- and physical performance variables, and whether change in fatigue after treatment was associated with changes in HRQoL and physical performance. Methods: Sixty patients were included for inpatient physiotherapy. Fifty-six patients completed the study and were available for analysis. Fatigue (Fatigue Severity Scale; FSS), HRQoL (Multiple Sclerosis Impact Scale; MSIS-29) and physical performance (walking ability and balance) were assessed at screening, baseline, after treatment and at follow-up after 3 and 6 months. We analysed possible associations between fatigue and other variables at baseline by regression models, and between change in fatigue versus changes in both HRQoL and physical performance variables after physiotherapy by correlation analysis. Results: Fatigue at baseline was associated with HRQoL (explained 21.9% of variance), but not with the physical performance tests. Change in fatigue was correlated with change in HRQoL, but not with changes in physical performance. All measures were improved after treatment (P < 0.001). While improvements in fatigue and HRQoL were lost at follow-up, improvements in physical performance tests were maintained for at least 6 months (P < 0.05). Conclusions: Fatigue was associated with HRQoL at baseline. Improvement in fatigue seemed to be related to other factors than improvement in physical performance. A broader strategy including both physical and psychological dimensions seems to be needed to improve fatigue over the long-term.