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