To assess the psychometric characteristics of the original 33-item Cedars-Sinai Health-Related Quality of Life in Rheumatoid Arthritis Questionnaire (O-CSHQ-RA) and 11-item CSHQ-RA Short Form (SF) using a representative population of patients with rheumatoid arthritis (RA) from 55 sites across the United States.
Data were from a 24-week multicenter, open-label, single-arm study of 312 RA patients receiving anakinra. Cronbach's alpha coefficient was used to indicate the internal consistency. Test-retest reliability was assessed by establishing the intraclass correlation coefficient (ICC) for screening and baseline visit responses. Convergent validity was tested with the Pearson correlation coefficient. Analysis of variance was performed to determine discriminant validity. A Wilcoxon signed-rank test and analysis of covariance were used to assess the responsiveness. A discriminant function was generated to determine the clinically meaningful change.
Test-retest reliability was demonstrated for both versions of the CSHQ-RA, with ICC ranging from 0.82 to 0.94. Cronbach's alpha coefficients were > or = 0.9, indicating good internal consistency. Pearson correlations between health-related quality of life instruments and CSHQ-RA measures ranged from -0.33 to -0.73 and 0.39 to 0.76, demonstrating good convergent validity. Scores on both versions of the CSHQ-RA differed significantly (p < 0.0001) for patients with different levels of physical disability as measured by the Stanford Health Assessment Questionnaire. Both instruments were responsive to differences in patient health as measured by the general health question (p < 0.0001). Clinically meaningful changes were calculated for all 5 domains of the O-CSHQ-RA (6.9-14.0) and the overall O-CSHQ-RA SF (12.7).
These results support the validity and reliability of both the original CSHQ-RA and the 11-item CSHQ-RA SF when tested in a representative patient population.