Development of a person-centered conceptual model of perceived fatigability
Perceived fatigability, reflective of changes in fatigue intensity in the context of activity, has emerged as a potentially important clinical outcome and quality of life indicator. Unfortunately, the nature of perceived fatigability is not well characterized. The aim of this study is to define the characteristics of fatigability through the development of a conceptual model informed by input from key stakeholders who experience fatigability, including the general population, individuals with multiple sclerosis (MS), and individuals with fibromyalgia (FM).
Thirteen focus groups were conducted with 101 participants; five groups with n = 44 individuals representing the general population, four groups with n = 26 individuals with MS, and four groups with n = 31 individuals with FM. Focus group data were qualitatively analyzed to identify major themes in the participants’ characterizations of perceived fatigability.
Seven major themes were identified: general fatigability, physical fatigability, mental fatigability, emotional fatigability, moderators of fatigability, proactive and reactive behaviors, and temporal aspects of fatigability. Relative to those in the general sample, FM or MS groups more often described experiencing fatigue as a result of cognitive activity, use of proactive behaviors to manage fatigability, and sensory stimulation as exacerbating fatigability.
Fatigability is the complex and dynamic process of the development of physical, mental, and/or emotional fatigue. Trait- and state-like biological, psychological, social, and environmental moderators contribute to tremendous variability in fatigability (both between and within-person variability). Future research to further characterize fatigability across populations, test treatments for fatigability, and develop new measures of this construct are greatly needed.
KeywordsFatigue Fatigability Multiple sclerosis Fibromyalgia Aging
Research reported in this publication was supported by the National Institute on Aging of the National Institutes of Health under Award Number R21AG053186; PI: Kratz. Dr. Kratz was supported during manuscript preparation by a grant from the National Institute of Arthritis and Musculoskeletal and Skin Diseases of the National Institutes of Health (Award Number K01AR064275). The U-M Pepper Center, which is funded by the National Institute of Aging (Award Number AG024824), provided assistance with subject recruitment. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
Compliance with ethical standards
Conflict of interest
The authors have no conflicts of interest to declare.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
Informed consent was obtained from all individual participants included in the study.
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