Using the Modified Fatigue Impact Scale for MS

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Fatigue is extremely common in multiple sclerosis (MS), affecting over 80 percent of MS patients. Even more, fatigue is reported by many to be their most debilitating MS symptom.

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The big problem with fatigue—other than the undeniable suffering it causes people—is its consequences. As fatigue persists without reprieve, it can negatively impact a person's quality of life and daily functioning.

To address fatigue, and its implications, experts have designed a test to appropriately measure the severity of one's fatigue. This test, called the Modified Fatigue Impact Scale (MFIS), can be used in clinical settings (your healthcare provider's office), as well as by investigators performing research studies.


The Modified Fatigue Impact Scale (MFIS) is one of ten scales that make up the Multiple Sclerosis Quality of Life (MSQLI) test—an instrument that provides information about the quality of life of a person living with MS.

The MFIS specifically evaluates the perceived impact of fatigue on a person's daily activities during the last four weeks.


Most people can take the MFIS by themselves; however, if a person has vision problems or upper limb impairments (e.g., muscle weakness or sensory deficits), a neurologist or other trained provider can administer the test.

There are two versions of the MFIS—a full-length version, which consists of 21 statements, and a shortened version, which consists of 5 statements.

The full-length version takes about 5 to 10 minutes to complete, while the abbreviated MFIS version takes 2 to 3 minutes to complete.


Participants taking the MFIS rate each statement on a 5-point scale, ranging from zero (never) to four (almost always). Since there are 21 questions on the full-length version, a total score can range from 0 to 84. Likewise, for the shortened version (5 statements), the total score can range from 0 to 20. Overall, the higher the score, the greater the fatigue.

The benefit of the full-length version is that three subscales are represented—physical, cognitive, and psychosocial.

This means that the test results may help a person delineate what part of their life their fatigue has the most impact—for example, their perceived strength to perform household chores (physical) versus their ability to concentrate or organize thoughts (cognitive) versus motivation to engage in social activities (psychosocial).

Example MFIS Statements

When scoring each statement, participants are asked to indicate, "How often fatigue has affected them in this way during the past 4 weeks." They can either enter 0 (never), 1 (rarely), 2 (sometimes), 3 (often), or 4 (almost always).

Here are the five statements from the shortened MFIS version:

  • I have been less alert.
  • I have limited in my ability to do things at home.
  • I have had trouble maintaining physical effort for long periods.
  • I have been less able to complete tasks that require physical effort.
  • I have had trouble concentrating.

The full-length version contains additional statements—a few examples include:

  • I have been clumsy and uncoordinated.
  • I have been forgetful.
  • My muscles have felt week.
  • My thinking has slowed down.


While the MFIS is a simple, straightforward, and well-regarded test, it's always a good idea to take a step back and consider how useful a test may be for you—two major points to consider are the reliability and validity of the test.


Reliability refers to how well the results can be trusted—in other words, does a person's MFIS score accurately reflect their degree of fatigue?

While the data on the reliability of the MFIS is limited, the studies available do suggest that the MFIS has an acceptable test-retest reliability.

This means that a person taking the MFIS on two separate occasions on the same day or days apart has been reported to have very similar, if not the same, scores.

Of course, despite these encouraging findings, some experts worry that factors like sleep or caffeine intake may actually affect the score, and should be addressed in future studies.

Moreover, some experts worry that fatigue is simply unstable in MS—so, devising a truly "reliable" fatigue scale may not be realistic.


Validity refers to how well a test measures what it is supposed to measure. To support MFIS's validity, investigators have found a correlation between a person's score on the MFIS and their scores on other fatigue scales, like the Fatigue Severity Scale (FSS). Moreover, a few studies have shown an improvement in the MFIS score with fatigue-treating interventions, like exercise or taking medication, like Provigil (modafinil).

That said, we don't know exactly what a change in score means—for instance, if a person's "cognitive" score improves by five points, does that mean a person can process information at a faster rate or have a better short-term memory?

In addition, MFIS scores have also been found to correlate with tests that evaluate depression (Beck Depression Inventory, or BDI). This suggests that the MFIS may not be able to tease out MS-related fatigue versus fatigue that occurs as a consequence of depression.

A Word From Verywell

If you are suffering from fatigue, it's important to talk with your practitioner. While your fatigue may be stemming from your MS, other factors may be contributing, as well, such as medication side effects or depression.

After accessing your fatigue, perhaps with the MFIS, you and your healthcare provider can devise a "combating your fatigue" plan that may encompass a variety of therapies—occupational therapy, exercise, stress management, or medication, to start.

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

By Colleen Doherty, MD
 Colleen Doherty, MD, is a board-certified internist living with multiple sclerosis.