Assessment of Fatigue in Rheumatoid Arthritis: A Psychometric Comparison of Single-item, Multiitem, and Multidimensional Measures

Martijn A.H. Oude Voshaar*, Peter M. ten Klooster, Christina Bode, Harald E. Vonkeman, Cees A.W. Glas, Tim Jansen, Iet van Albeda-Kuijpers, Piet L.C.M. van Riel, Mart A F J van de Laar

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Objective. To compare the psychometric functioning of multidimensional disease-specific, multiitem generic, and single-item measures of fatigue in patients with rheumatoid arthritis (RA).

Methods. Confirmatory factor analysis (CFA) and longitudinal item response theory (IRT) modeling were used to evaluate the measurement structure and local reliability of the Bristol RA Fatigue Multi-Dimensional Questionnaire (BRAF-MDQ), the Medical Outcomes Study Short Form-36 (SF-36) vitality scale, and the BRAF Numerical Rating Scales (BRAF-NRS) in a sample of 588 patients with RA.

Results. A 1-factor CFA model yielded a similar fit to a 5-factor model with subscale-specific dimensions, and the items from the different instruments adequately fit the IRT model, suggesting essential unidimensionality in measurement. The SF-36 vitality scale outperformed the BRAF-MDQ at lower levels of fatigue, but was less precise at moderate to higher levels of fatigue. At these levels of fatigue, the living, cognition, and emotion subscales of the BRAF-MDQ provide additional precision. The BRAF-NRS showed a limited measurement range with its highest precision centered on average levels of fatigue.

Conclusion. The different instruments appear to access a common underlying domain of fatigue severity, but differ considerably in their measurement precision along the continuum. The SF-36 vitality scale can be used to measure fatigue severity in samples with relatively mild fatigue. For samples expected to have higher levels of fatigue, the multidimensional BRAF-MDQ appears to be a better choice. The BRAF-NRS are not recommended if precise assessment is required, for instance in longitudinal settings.
Original languageEnglish
Pages (from-to)413-420
Number of pages8
JournalJournal of rheumatology
Issue number3
Publication statusPublished - 1 Mar 2015


  • Fatigue
  • Confirmatory factor analysis
  • Item response theory
  • rheumatoid arthritis
  • 2023 OA procedure


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