Detailled Information)

Name of the Instrument/Tool Multidimensional Fatigue Inventory (MFI-20)
First Description

Smets E, Garssen B, Bonke Bd, De Haes J. The Multidimensional Fatigue Inventory (MFI) psychometric qualities of an instrument to assess fatigue. Journal of psychosomatic research. 1995;39(3):315-25.

Year 1995
Concept of constructs Fatigue, Functional status
Population/Disease Generic
Originally developed for ---
Other rheumatic diseases
where can be applied (only if validated)
Fibromyalgia (FM), Systemic Lupus Erythematosus (SLE), Rheumatoid Arthritis (RA), Ankylosing spondylitis (AS), ANCA-associated vasculitis (AAV)
Additional population with no rheumatic diseases Yes
cancer, liver disease
Language: Originally published in English
Available in Language Danish, Croatian, Chinese, Norwegian, Finnish, French, Romanian, Korean, Spanish, Swedish, Czech, Italian, German, Polish, Lithuanian, Dutch
Author/s Smets EM, Garssen B, Bonke B, De Haes JC
Title The Multidimensional Fatigue Inventory (MFI) psychometric qualities of an instrument to assess fatigue
Journal Journal of Psychosomatic Research
Year 1995
Vol 39
Num 3
Pages 315-25
Country Netherlands
Language English
Other references of interest
Brief Description

Application of the multidimensional fatigue inventory (MFI-20) in cancer patients receiving radiotherapy.

Brief Description

Measuring fatigue among women with Sjogren’s syndrome or rheumatoid arthritis: a comparison of the Profile of Fatigue (ProF) and the Multidimensional Fatigue Inventory (MFI).

Brief Description

Physical Fatigue, Fitness, and Muscle Function in Patients With Antineutrophil Cytoplasmic Antibody-Associated Vasculitis.

Instrument/Tool Translations References
Brief Description

Validation of the French 'multidimensional fatigue inventory' (MFI 20). 

Brief Description
Assessment of fatigue in patients with fibromyalgia and chronic widespread pain. Reliability and validity of the Swedish version of the MFI-20. 
Brief Description
Linguistic validation of six patient-reported outcomes instruments into 12 languages for patients with fibromyalgia. 
Correspondence to Smets EM
Address Medical Psychology J3-220, Academic Medical Center, University of Amsterdam, PO Box 22660, 1100 DD Amsterdam, The Netherlands
Available the developer can be contacted.

The MFI-20 is copyrighted on the names of the authors. The MFI is free for academic use, charges apply for commercial use. For further information, the developers can be contacted.

Type Of Measure Questionnaire, Scale
Brief Description

The MFI was originally developed to measure cancer fatigue and it was evaluated initially in cancer and chronic fatigue syndrome (CFS) patients and in healthy volunteers who might be physically tired (army recruits) or cognitively tired (junior doctors).

The MFI covers domains of general fatigue, physical fatigue, activity, motivation, and mental fatigue (5 subscales with 4 items each). Each item had 7 response options in the original MFI-20, but this was revised to the current version with 5 response options.

Number of Items 20 items; 5 subscales
Range 4-20 for each subscale
Responses options/scale Yes
scored 1–5
Developed for Not specified
Method of administration Self-administered
Recommendations to score

Items are scored 1–5, with 10 positively phrased items reverse scored (this concerns following items: 2, 5, 9, 10, 13, 14, 16, 17, 18, 19). For each of the 5 scales (general fatigue, physical fatigue, reduced activity, reduced motivation, and mental fatigue) a total score is calculated by summation of the scores of the individual items. Scores can range from the minimum of 4 to the maximum of 20. The use of a total score over all 20 items is not recommended.

Score Interpretation Higher scores reflect greater severity/ higher fatigue.
Cut-off points ---
Cut-off points applied to ---
Smallest detectable change if described ---
Smallest detectable change applied to ---
Completion time by the patient - minutes
Scoring time by the assessor - minutes
Training to score Not necessary
Strengths Useful in clinical practice & research
Limitations Floor effect
Limitations >=5 European languages (English)

Authorized versions of the questionnaire are available in several languages. These can be obtained under the same conditions (by contacting the developers).

A. Internal Consistency Tested
Cronbach's (Describe)

Cronbach’s alpha for most subscales ranged from 0.85–0.89 (in patients with RA or primary Sjogren syndrom, PSS)

B. Reliability intraobserver or test-retest Tested
Continuous scores: intraclass
correlation coefficient (ICC)
Dichotomus: Cohen kappa (Describe)

In AS and PSS: ICC= 0.57–0.85 across the subscales.

In patients with chronic widespread pain or FMS: ICC=0.75–0.92.

C. Reliability interobserver or Measurement error Not Tested
Standard error of measurement (SEM),
smallest detectable change (SDC) or
Limits of agreement (LoA) (Describe)
A. Content validity: face validity Tested
Expert opinion (relevance and
comprehensiveness) (Describe)

The 5 fatigue domains were  generated from 24 draft items developed from existing literature and in-depth interviews with patients with cancer. For each of these 5 domains, experts tried to create brief, positively and negatively phrased items that exclude somatic issues.

B. Construct Validity:
Structural validity
Brief Description

Factor analysis on the 24 items supported the 5 subscales with adjusted goodness of fit index ranging from 0.95 to 0.98.

Hypotheses-testing Tested
Brief Description

In RA, subscales correlated strongly with depression (r=0.58–0.74). Disease Activity Score was moderately associated with general fatigue, physical fatigue, and reduced activity (r=0.42–0.47).

In AS and RA, 4 subscales correlated with SF-36 vitality subscale (r= -0.53 to -0.74), while mental fatigue correlated less strongly (r= -0.42 and -0.4, respectively).

Correlations with a fatigue VAS in RA and PSS were strong for general fatigue (0.7 and 0.77, respectively), physical fatigue (0.67 and 0.72, respectively), and reduced activity (0.54 and 0.58, respectively), but moderate for reduced motivation (0.31 and 0.53, respectively) and mental fatigue (0.34 and 0.39, respectively). In FMS, correlations with a fatigue VAS were 0.62 for general fatigue, but 0.32–0.36 for the remaining subscales.

Comparison in AAV patients vs healthy controls (median, IQR): 13 (8-16) vs 5.5 (4-8), p< 0.001 * AAV vs other vasculitides (median, range): Behcet's: 17.0 (7-20) PCNSV: 16.0 (4-20) EGPA: 16.1 (4-20) GCA: 16.0 (4-20) GPA: 15.0 (4-20) HSP: 14.5 (4-20) MPA: 15.5 (4-20) PAN 16.0 (4-20) TAK: 16.0 (4-20)

Cross-cultural validity Tested
Brief Description

Validation of the PROs were performed for the Polish version in cancer patients, Spanish version in fibromyalgia patients, Chinese version in cancer patients, Swedish version in fibromyalgia and chronic widespead patients and French version in cancer patients.

C. Criterion validity Not Tested
Comparison with a 'gold standard' Continuous scores:
correlations, ROC curves Dichotomus:
Sensitivity & Specificity (Describe)
Responsiveness Tested
Ability to detect change over
time Multiple methods (Describe)

Sensitivity to change was demonstrated for MIF-20 in patients with SA, FM, SLE and RA for all subscales and also for the total score (although the use of the total score is not recommended by authors).

Interpretability Tested
of responders with the highest/lowest
score Minimal important difference (MID) (Describe)

In patients with cancer, 10.4–33.6% scored the best possiblescore for the different subscales (mental fatigue 33.6%), suggesting a potentially substantial ceiling effect; 4.5– 15.7% scored the worst possible score (reduced activity 15.7%), suggesting a lesser, but still potentially important floor effect. No data could be found for rheumatology populations.

In AS patients randomized to spa therapy, effect sizes were: general fatigue 0.82, physical fatigue 0.81, reduced activity 0.28, reduced motivation 0.52, and mental fatigue 0.38.

In FM, a significant improvement was seen in a 20-item–totaled MFI score after milnacipran.

Also using the 20-item totaled MFI score (not recommended by the developers), and based on linear regression analysis on comparative fatigue ratings from patients after paired interviews, the effect size required for an average patient to move to a different fatigue category (i.e., much, somewhat or a little, less or more fatigued) is calculated as 0.76 in RA. In SLE, again using the totaled 20 items with a range of 20–100, the effect size was 0.59 (95% confidence interval [95% CI] 0.42–0.72), which the authors also present as MFI minimum clinically important difference score of 11.5 (95% CI 8.0 –15.0).

Other Comments ---
Outcome Measure

For further information, please contact the developers.

Document 1 MFI_Original manuscript