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Keywords:

  • Rheumatoid arthritis;
  • Quality of life;
  • Instrument validation

Abstract

Objective

To improve accuracy and content coverage of the original 33-item Cedars-Sinai Health-Related Quality of Life for Rheumatoid Arthritis Instrument (CSHQ-RA).

Methods

A total of 312 RA patients from 55 sites were screened in a 24-week trial. Patients completed an expanded 48-item version of the CSHQ-RA, Medical Outcomes Study Short Form 36 (MOS SF-36), and Stanford Health Assessment Questionnaire (HAQ) Disability Index at 5 visits. The revised CSHQ-RA was created based on response frequencies and distributions, item-to-item correlation, factor and Rasch analysis, and input from experts. Psychometric evaluation included internal consistency, test–retest reliability, convergent and discriminant validity, and responsiveness. Minimum clinically important difference (MCID) was also measured.

Results

Response rates were 93% at baseline and 71% at 12 weeks. Eighty-one percent of respondents at baseline were women, mean ± SD age was 52 ± 12 years, and mean ± SD duration of RA was 10.8 ± 10.4 years. The revised CSHQ-RA included 36 items measuring 7 domains (4 original and 3 new). All Cronbach's alpha coefficients were >0.8, indicating good internal consistency. Test–retest reliability measured intraclass correlation coefficients, which ranged from 0.86 to 0.95. All 7 domains correlated significantly with the MOS SF-36 and HAQ, indicating good convergent validity. Analysis of variance of disability group scores showed good discriminant validity (P < 0.0001). The MCIDs ranged from 6.2 for social well-being to 14.8 for pain/discomfort.

Conclusion

The revised CSHQ-RA was validated using a broader RA patient population. It captures 3 additional domains (social well-being, pain/discomfort, and fatigue), which allow for measuring all important aspects of health-related quality of life.