E3 PreliminaryModerate confidencePEM not requiredMethods-PaperPeer-reviewedReviewed
Standard · 3 min
The Multidimensional Fatigue Inventory (MFI) psychometric qualities of an instrument to assess fatigue.
Smets, E M, Garssen, B, Bonke, B et al. · Journal of psychosomatic research · 1995 · DOI
Quick Summary
Researchers created and tested a questionnaire called the Multidimensional Fatigue Inventory (MFI) to measure different types of fatigue people experience. The 20-question survey asks about general tiredness, physical exhaustion, mental tiredness, motivation, and activity levels. When they tested it with various groups—including people with chronic fatigue syndrome—the questionnaire worked well and reliably measured fatigue in all groups.
Why It Matters
The MFI is one of the few validated instruments specifically tested in ME/CFS populations and addresses the multidimensional nature of fatigue beyond simple exhaustion. Having a reliable, psychometrically sound measurement tool is crucial for ME/CFS research, enabling consistent assessment of treatment effects and disease burden across studies. This standardized approach improves the ability to compare results between research groups and clinics.
Observed Findings
The five-factor model fit data from all six sample groups with AGFI values exceeding 0.93.
Average internal consistency (Cronbach's alpha) was 0.84 across all dimensions.
Correlations between MFI scales and visual analogue fatigue ratings ranged from 0.22 to 0.78.
The instrument distinguished between groups with different fatigue levels based on clinical circumstances and activity levels.
Chronic fatigue syndrome patients were among the groups in which the five-factor structure was confirmed.
Inferred Conclusions
The MFI is a valid and reliable multidimensional measure of fatigue applicable across diverse populations.
The five-factor structure of fatigue (general, physical, mental, motivation, activity) appears to be stable and generalizable.
The instrument demonstrates adequate construct and convergent validity for measuring fatigue in clinical and non-clinical settings.
The MFI can be used as a standardized assessment tool in fatigue research and clinical practice.
Remaining Questions
How sensitive is the MFI to changes in fatigue over time (test-retest reliability and responsiveness)?.
What This Study Does Not Prove
This study validates the MFI's structural reliability and internal consistency but does not establish whether the instrument is sensitive to changes over time (responsiveness) or whether it can distinguish ME/CFS from other fatiguing conditions. The study does not prove the MFI captures disease-specific features of ME/CFS such as post-exertional malaise, and correlation with visual analogue scales does not confirm the questionnaire measures the underlying biological mechanisms of fatigue.
Tags
Symptom:Fatigue
Method Flag:Mixed CohortWeak Case DefinitionExploratory Only
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
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