Assessment of Fatigue in Multiple Sclerosis

Fatigue represents one of the most prevalent and debilitating symptoms in multiple sclerosis, exerting profound effects on daily functioning, employment, social participation and quality of life. It is a complex and multifaceted phenomenon encompassing physical exhaustion, cognitive slowing and diminished psychosocial resilience. Assessment strategies combine patient-reported outcome measures with clinician-rated scales and, increasingly, objective indices such as actigraphy or cognitive performance tasks. Key challenges include the heterogeneity of fatigue presentations, the overlap with depression and sleep disorders, and the need for instruments that capture both unidimensional severity and multidimensional impact. Advances in psychometric analysis—such as Rasch modelling and exploratory factor analysis—have refined the measurement properties of existing scales and guided the development of new indices aligned to the lived experience of people with MS. Harmonisation of assessment tools is critical for clinical trials, epidemiological studies and personalised management, ensuring that interventions targeting fatigue can be accurately evaluated and optimised.

Research from Nature Portfolio

Recent studies have employed clustering algorithms and in-depth factor analytic techniques to probe the underlying structure of fatigue in people with multiple sclerosis. One seminal investigation used combined scores from four well-established self-report scales to identify patient subgroups, revealing that profiles differ primarily by overall severity rather than by discrete physical, cognitive or psychosocial dimensions. Subsequent exploratory factor analysis of 54 items across these measures confirmed a complex, multidimensional construct, yielding multiple latent factors rather than a single global factor. These findings have important implications for both clinical assessment and trial design, emphasising the need to tailor interventions according to severity strata and to maintain a multidimensional perspective when interpreting changes in fatigue over time.

Assessment of Fatigue in Multiple Sclerosis publication trend

The graph below shows the total number of articles in assessment of fatigue in multiple sclerosis across all publications each year (not limited to Nature Index journals).

Technical terms

Fatigue Severity Scale (FSS): A self-report questionnaire measuring the impact of fatigue on daily functioning using a unidimensional score.

Modified Fatigue Impact Scale (MFIS): A 21-item instrument assessing physical, cognitive and psychosocial aspects of fatigue.

Expanded Disability Status Scale (EDSS): A clinician-rated scale quantifying neurological impairment and disability in multiple sclerosis.

Rasch analysis: A probabilistic modelling technique used to evaluate and refine the measurement properties of rating scales, ensuring unidimensionality and interval-level scoring.

Exploratory factor analysis: A statistical method for identifying latent constructs by examining the pattern of correlations among observed variables.

References

1. Validity and reliability of the Fatigue Severity Scale in Finnish multiple sclerosis patients. Brain and Behavior (2017).
2. Development of a patient reported outcome scale for fatigue in multiple sclerosis: The Neurological Fatigue Index (NFI-MS). Health and Quality of Life Outcomes (2010).
3. Fatigue Profiles in Patients with Multiple Sclerosis are Based on Severity of Fatigue and not on Dimensions of Fatigue. Scientific Reports (2020).
4. Relationship between Fatigue and Physical Activity in a Polish Cohort of Multiple Sclerosis Patients. Medicina (2020).