Patient-Reported Outcome Measures for Understanding Fatigue in MS Remain Limited

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Researchers find that a refinement of patient-reported outcome measures is needed to understand the drivers of underlying fatigue in patients with multiple sclerosis.

STOCKHOLM — While the patient-reported outcome (PRO) Modified Fatigue Impact Scale (MFIS) offers greater information about fatigue subtypes than commonly used unidimensional PRO fatigue measures in patients with multiple sclerosis (PwMS), refinement of PRO measures is needed to understand the drivers of underlying fatigue in most patients, a study presented at the 35th Congress of the European Committee for Treatment and Research in Multiple Sclerosis, in Stockholm, suggests.

“Fatigue in people with multiple sclerosis is not only common, it might be a primary driver of disability,” corresponding study author, Mark Gudesblatt, MD, of South Shore Neurologic Associates, told Neurology Advisor. “For improved ability to address patient symptoms optimally, understanding what drives their complaints requires information then is typically able to fully obtain in the course of routine care visits. Incorporation of PROs can provide an enhancement to the history to help focus or target what underlies symptomatic complaints.”

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The study was a retrospective review of a prospective patient registry consisting of PwMS. Only participants who completed the MFIS and the unidimensional Fatigue Severity Scale (FSS) in addition to the variability of these fatigue along a continuum of disability (PDDS) scores were included in the analysis (n=224).

Researchers found that average scores on the FSS and the MFIS – the latter of which comprised global, physical, and psychosocial dimensions – increase with early disability. The elevation of these scores is sustained beyond low levels of disability (PDDS 2). Conversely, MFIS cognitive fatigue increases and then peaks at low disability levels, subsequently declining with increasing physical disability. The variability of PRO measures is at a maximum at the low PDDS disability levels, yet the variability declines with increased PDDS disability.

Limitations of the study include its retrospective nature as well as the reliance on self-reported PROs for evaluating fatigue symptoms.

“Fatigue is a very complex substrate related to psychosocial, cognitive, physical, sleep, hormonal, vitamin deficiency, and so many other potential contributing factors,” explained Dr. Gudesblatt. “Improved understanding of the underlying factors causing the symptom can provide a path to improved treatment and outcomes as well as patient satisfaction and reduced disability.”

Dr. Gudesblatt concluded that this study “demonstrates that fatigue in people with MS even when including a PRO evaluation can be problematic in that 22% of people with MS when queried the same day will have discordant results (high-low) with use of 2 validated fatigue PRO (modified fatigue impact and fatigue severity scales) and also that cognitive fatigue might drive early complaints of fatigue prior to the appearance of significant physical disability.”


Ciszewska K, Srinivasan J, Fafard L, et al. Patient reported fatigue and disability in multiple sclerosis: it matters how you ask and when you ask. Abstract presentation at: 35th Congress of the European Committee for Treatment and Research in Multiple Sclerosis; September 11-13, 2019; Stockholm, Sweden. Abstract EP1485.