Abstract
Objective
To estimate the minimal clinically important difference (MCID) of seven measures of
fatigue in rheumatoid arthritis.
Study Design and Setting
A cross-sectional study design based on interindividual comparisons was used. Six
to eight subjects participated in a single meeting and completed seven fatigue questionnaires
(nine sessions were organized and 61 subjects participated). After completion of the
questionnaires, the subjects had five one-on-one 10-minute conversations with different
people in the group to discuss their fatigue. After each conversation, each patient
compared their fatigue to their conversational partners on a global rating. Ratings
were compared to the scores of the fatigue measures to estimate the MCID. Both nonparametric
and linear regression analyses were used.
Results
Nonparametric estimates for the MCID relative to “little more fatigue” tended to be
smaller than those for “little less fatigue.” The global MCIDs estimated by linear
regression were: Fatigue Severity Scale, 20.2; Vitality scale of the MOS-SF36, 14.8;
Multidimensional Assessment of Fatigue, 18.7; Multidimensional Fatigue Inventory,
16.6; Functional Assessment of Chronic Illness Therapy–Fatigue, 15.9; Chalder Fatigue
Scale, 9.9; 10-point numerical Rating Scale, 19.7, for normalized scores (0–100).
The standardized MCIDs for the seven measures were roughly similar (0.67–0.76).
Conclusion
These estimates of MCID will help to interpret changes observed in a fatigue score
and will be critical in estimating sample size requirements.
Keywords
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Article info
Publication history
Published online: March 25, 2008
Accepted:
August 21,
2007
Identification
Copyright
© 2008 Elsevier Inc. Published by Elsevier Inc. All rights reserved.
