Modified Fatigue Impact Scale (MFIS)
The MFIS is a modified form of the Fatigue Impact Scale (Fisk et al, 1994b) based on items derived from interviews with MS patients concerning how fatigue impacts their lives. This instrument provides an assessment of the effects of fatigue in terms of physical, cognitive, and psychosocial functioning. The full-length MFIS consists of 21 items while the abbreviated version has 5 items. The abbreviated version can be used if time is limited but the full-length version has the advantage of generating subscales. The MFIS is one of the components of the MSQLI.
Administration time is approximately 5-10 minutes for the full-length version and 2-3 minutes for the abbreviated version.
The MFIS is a structured, self-report questionnaire that the patient can generally complete with little or no intervention from an interviewer. However, patients with visual or upper extremity impairments may need to have the MFIS administered as an interview. Interviewers should be trained in basic interviewing skills and in the use of this instrument.
The total score for the MFIS is the sum of the scores for the 21 items. Individual subscale scores for physical, cognitive, and psychosocial functioning can also be generated by calculating the sum of specific sets of items.
The MFIS is easy to administer and focuses on the ways in which MS-related fatigue affects everyday life. As such it has high face validity for patients. The availability of the three subscales, physical, cognitive, and psychosocial functioning, may be useful to investigators interested in testing hypotheses concerning these different areas of function. However, the three subscales tend to correlate highly with one another, which limits their usefulness to some extent.
The full-length version of the MFIS has a Cronbach's alpha of .81 while the short form has an alpha of .80. The original version, the Fatigue Impact Scale, was sensitive in discriminating the effects of fatigue among MS from those of patients with chronic fatigue syndrome and essential hypertension. (Fisk et al, 1994a)