The Relationship between Self-reported Fatigue, Fatigability, and Sleep Quality in Individuals with Multiple Sclerosis

The average lifetime cost of care for people with Multiple Sclerosis (PwMS) in the United States is approximately $2.2 million per person affected, and up to 80% of PwMS are unemployed within 10 years of disease onset. MS-related fatigue is a debilitating symptom experienced by around 90% of PwMS, it can significantly affect an individual’s functional quality of life by interfering with activities of daily living (ADLs), causing reduced work performance, and contributing to loss of employment. MS-related fatigue is an umbrella term that encompasses the individual’s perceptions of fatigue (perceived fatigue) and measurable deterioration in performance (fatigability). Perceived fatigue and fatigability interfere with the individual’s efficient performance of physical and cognitive tasks and both should be considered during the assessment and management of MS-related fatigue. What further makes MS-related fatigue complex is that not only the disease process itself can cause fatigue, but also other prevalent comorbidities likely contribute to fatigue in MS such as depression and sleep disturbances. Therefore, the approach undertaken in the current body of research was under the notion that a multidisciplinary approach would seem best to optimally assess fatigue in PwMS. Perceived fatigue in PwMS is measured using self-reported scales which are used extensively in the MS-related fatigue field of research. However, there have been recent concerns regarding the psychometric properties of commonly used perceived fatigue scales in PwMS. This is an issue as interpreting the findings of those previous studies is now somewhat difficult. The current study utilized a more psychometrically sound perceived fatigue scale that has been validated for use in PwMS, called the Neurological Fatigue Index (NFI-MS). What makes the NFI-MS a unique measure of perceived fatigue in PwMS is that to our knowledge, it