Fatigue and fluctuations in physical and psychological wellbeing in people with multiple sclerosis: A longitudinal study

Background: Fatigue is a highly prevalent and disabling symptom of multiple sclerosis (MS). The aetiology remains unclear, potentially resulting from neuroinflammatory or neurodegenerative processes, mood disturbance, MS symptoms including pain, poor sleep, physical decompensation or medication side effects. Cross-sectional associations have been reported between fatigue and markers of physical and psychological health in people with MS. The current study examined if fluctuations in markers of physical and psychological wellbeing were associated with between-person differences in fatigue in MS. Methods: Longitudinal data of up to 7 years was available of 3369 people with MS who were enrolled in the UK MS Register. Participants completed MS impact scale ratings and MS walking scales up to 4 times per year for up to 7 years. Fatigue was assessed at one time point using the Fatigue Severity Scale. Multilevel analyses were conducted to examine the degree of variance in the outcome measures accounted for by fatigue. Results: Fatigue was associated with fluctuations in depression, MS impact, and walking ability, and to a lesser extent with fluctuations in anxiety and perceived health status. Interference of fatigue in participation in social activities and work-related responsibilities and the physical effects of fatigue were most strongly related to MS-related outcomes. Conclusion: Given the strong associations between fatigue and many MS outcomes, fatigue management interventions are likely to impact on different aspects of physical and psychological wellbeing in MS.