The Modified Fatigue Impact Scale (commonly abbreviated MFSIS) is a 21 items rating questionnaire selected from the "Fatigue Impact Scale" (FIS), a multidimensional scale developed to assess the perceived impact of fatigue on a variety of daily activities (Fisk, Ritvo, Ross, Haase, Murray, & Schlech, 1994). The items of the MFIS can be aggregated into three subscales (Physical, Cognitive, and Psychosocial), as well as into a total MFIS (Multiple Sclerosis Quality of Life Inventory) score. A total of 84 points are possible. All items are scaled so that higher scores indicate a greater impact of fatigue on a patient’s activities. The MFIS is also available in an abbreviated 5 items version.