The Fatigue Severity Impact Questionnaire-Relapsing Multiple Sclerosis (FSIQ-RMS) may be the most suitable patient-reported outcome (PRO) instrument for measuring progressive multiple sclerosis, according to a new study published in Neurology and Therapy.

The researchers found that 80% (n=24) of the patients with progressive MS interviewed experienced both physical and mental fatigue and that the patients characterized them separately. The interviews revealed 23 unique concepts of fatigue symptoms and 42 impacts of fatigue on daily life.

“This qualitative study of a progressive MS population combined a patient-centric approach with robust methods of qualitative data analysis to gain a greater understanding of the key concepts, humanistic burden, and impact of MS-related fatigue in this population,” the authors said.

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Some of the most common concepts reported for physical fatigue included feeling physical fatigue, physically tired, having low energy, weakness, exhaustion, and feeling drained. The most commonly reported concepts of mental fatigue were feeling mentally fatigued, mentally tired, having difficulty thinking clearly, having a loss of focus, and a loss of concentration.

Fatigue affected a number of aspects of daily life as well as including patients’ emotional wellbeing, work/school, mobility, activities of daily life, and social life. The most commonly reported coping strategies included periodic resting, pacing themselves, avoiding heat, and napping.

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The study compared the list of patient-identified fatigue concepts with existing MS-specific fatigue PRO instruments including the Modified Fatigue Impact Scale (MFIS), Fatigue Severity Scale (FSS), FSIQ-RMS, Quality of Life in Neurological Disorders Fatigue Scale (Neuro-QoL FS), and Functional Assessment of MS (FAMS).

The PRO instruments were evaluated based on the amount of overlap they had with the concepts reported in the interviews. The FSS, Neuro-QoL FS, and FAMS were found to have low suitability for progressive MS due to the omission of key concepts reported by the patients and/or a lack of distinction between mental and physical aspects of fatigue.

The MFIS had high levels of overlap with most patient-endorsed concepts but did not include some aspects such as tiredness. The MFIS also included several concepts that were not commonly mentioned by patients including difficulty with decision making, forgetfulness, and physical discomfort. All of the 20 concepts on the FSIQ-RMS were reported by patients with progressive MS, with forgetfulness being the only concept that was not mentioned commonly.

“The FSIQ-RMS was deemed the most appropriate for assessing fatigue in patients with progressive MS, based on concordance with the qualitative data collected from this research study; this supports similar fatigue concepts and presentation among patients with relapsing MS and patients with progressive MS,” the authors concluded.


Watson C, Scippa K, Barlev A, Kresa-Reahl K, Cole JC. Results from patient interviews on fatigue in progressive multiple sclerosis and evaluation of fatigue patient-reported outcome (PRO) instruments. Neurol Ther. Published online March 9, 2022. doi:10.1007/s40120-022-00337-9