Measurement Characteristics and Clinical Utility of the Modified Fatigue Impact Scale in Individuals With Multiple Sclerosis

Multiple sclerosis (MS) is an autoimmune disease affecting approximately 2.3 million people worldwide.¹ Fatigue occurs in approximately 80% of individuals with MS.² The Modified Fatigue Impact Scale (MFIS) is a modified form of the Fatigue Impact Scale,³ based on items derived from interviews with patients with MS concerning how fatigue affects their lives. The full-length MFIS has 21 items, whereas the short version has 5 items. The full-length version generates 3 subscales (physical, cognitive, and psychosocial functioning), which assess the perceived effect of fatigue during the last 4 weeks.⁴ Participants rate the MFIS on a 5-point Likert scale from 0 (never) to 4 (almost always). Total scores range from 0 to 84; for the subscale scores, the physical subscale ranges from 0 to 36, the cognitive subscale ranges from 0 to 40, and the psychosocial functioning subscale ranges from 0 to 8. The scores range from 0 to 20 for the 5-item version. Higher numbers indicate greater fatigue. The scale has been shown to have adequate to excellent concurrent and content validity^{4.,  5.,  6.,  7.} and excellent test-retest reliability in patients with MS.^{4.,  5.} Rasch analysis revealed that the 21-item scale was found to contain a physical and cognitive dimension (the original 2 social items were found to be part of the physical dimension).^{4.,  5.} Additionally, the MFIS has been found to show change after a 4-week intervention.^{4.,  5.} The MFIS can be administered and scored in 5 to 10 minutes, making it a clinically useful and low-burden instrument. The MFIS is free to use, and has been recommended by the Neurology Section of the American Physical Therapy Association's Multiple Sclerosis Taskforce.

This abbreviated summary provides a review of the psychometric properties of the MFIS in people with MS. A full review of the MFIS and reviews of nearly 377 other instruments for patients with various health conditions can be found at www.rehabmeasures.org.

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This instrument summary is designed to facilitate the selection of outcome measures by clinicians. The information contained in this summary represents a sample of the peer-reviewed research available at the time of this summary's publication. The information contained in this summary does not constitute an endorsement of this instrument for clinical practice. The views expressed are those of the summary authors and do not represent those of authors' employers, instrument owner(s), the Archives of Physical Medicine and Rehabilitation, the Rehabilitation Measures Database, or the U.S. Department of Health and Human Services. The information contained in this summary has not been reviewed externally.

The Rehabilitation Measures Database and Instrument Summary Tear-sheets were initially funded by the National Institute on Disability, Independent Living, and Rehabilitation Research, U.S. Department of Health and Human Services, through the Rehabilitation Research and Training Center on Improving Measurement of Medical Rehabilitation Outcomes (grant no. H133B090024).