A self-administered rheumatoid arthritis disease activity index (RADAI) for epidemiologic research. Psychometric properties and correlation with parameters of disease activity

Arthritis Rheum. 1995 Jun;38(6):795-8. doi: 10.1002/art.1780380612.


Objective: To examine the psychometric properties and construct validity of a self-administered Rheumatoid Arthritis Disease Activity Index (RADAI).

Methods: Five items of the Rapid Assessment of Disease Activity in Rheumatology (RADAR) questionnaire were aggregated into the RADAI and assessed for their factor loading, internal consistency, and construct validity.

Results: In 55 patients with RA, the RADAI had a high internal consistency (Cronbach's alpha = 0.91) and correlated with physician's assessment of disease activity (r = 0.54, P < 0.01), the swollen joint count (r = 0.54, P < 0.01), and the C-reactive protein value (r = 0.43, P < 0.01).

Conclusion: The RADAI is a highly reliable and valid self-administered measure of disease activity for clinical, health services, and epidemiologic research. Its sensitivity to change in longitudinal studies needs further study.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Arthritis, Rheumatoid / epidemiology*
  • Arthritis, Rheumatoid / physiopathology*
  • Arthritis, Rheumatoid / psychology
  • C-Reactive Protein / analysis
  • Female
  • Humans
  • Joints / physiopathology
  • Male
  • Middle Aged
  • Psychometrics
  • Reproducibility of Results
  • Severity of Illness Index*
  • Surveys and Questionnaires


  • C-Reactive Protein