Tired of not knowing what that fatigue score means? Normative data of the Modified Fatigue Impact Scale (MFIS)

Background: The Modified Fatigue Impact Scale (MFIS) is one of the most common self-report measures used to assess fatigue in multiple sclerosis (MS). Despite its widespread use, there are no existing normative data for the MFIS.

Objective: The present investigation aimed to develop normative data for the MFIS in a large community sample, stratified by age, gender, and education and to compare the derived new cutoffs to an existing cutoff.

Methods: A total of 675 healthy individuals, stratified by age, gender, and education completed the MFIS. After the removal of 19 outliers, the final sample consisted of 656 individuals. Archival data of 540 individuals with MS who completed the MFIS were also included to analyze the utility of the new cutoffs.

Results: There were no main effects on the MFIS for gender. However, there were main effects for age and education. Specifically, younger cohorts (25-34 and 35-44) reported less physical fatigue compared to the two oldest cohorts (55-64 and 65-74). Similar effects were found for total MFIS fatigue with individuals aged 55-64 reporting greater overall fatigue than 35-44 year olds. Finally, 18-24 year olds reported significantly higher levels of cognitive fatigue compared to 35-44 and 65-74 aged cohorts. No other effects were observed for age. Individuals with higher education consistently reported less fatigue. Subsequent analyses also revealed an interaction effect for age x gender. When examining the age x gender interaction, women age 18-24 reported significantly greater levels of physical, cognitive, psychosocial, and total fatigue than their male counterparts. In contrast, men aged 65-74 reported greater physical, cognitive, and total fatigue than women their age. Comparisons of the existing cutoff of the MFIS to the new age, gender, and education specific cutoffs found either comparable or slightly higher rates of fatigue with the latter.

Conclusion: Based on these findings, updated normative data and age, gender, and education specific cutoffs are provided. Utilization of these updated norms will result in a more accurate assessment of fatigue and will be valuable for those conducting research and/or clinical practice with individual with MS.