| Abstract: | Objective To test the validity and reliability of a newly developed disease‐specific multidimensional quality of life instrument: the Cedars‐Sinai Health‐Related Quality of Life Instrument (CSHQ‐RA). Methods A total of 350 rheumatoid arthritis (RA) patients were asked to complete the CSHQ‐RA at 2 time points (4 weeks apart). Patients also completed the Medical Outcomes Study Short Form 36 (SF‐36) and the Stanford Health Assessment Questionnaire (HAQ) Disability Index (DI) at the second time point. Construct validity was tested, using Pearson's correlations, by comparing subscale scores on the CSHQ‐RA to those obtained from the mental component summary (MCS) and physical component summary (PCS) of the SF‐36. HAQ DI scores were used to assess the discriminant validity of the CSHQ‐RA. Intraclass correlation coefficients (ICCs) were used to assess test–retest reliability. Results Response rates for the first and second survey were 83% (291) and 93% (276), respectively; 84% of respondents were women, and mean age was 57 years. Mean scores ± SDs on instruments were: HAQ 0.73 ± 0.69; MCS 49 ± 12; and PCS 33 ± 11. Pearson's correlations between the CSHQ‐RA subscale scores and the SF‐36 scores ranged from 0.55 to 0.76 (P < 0.001). Analysis of variance indicate that scores on the CSHQ‐RA discriminated between levels of physical disability as measured by the HAQ (P < 0.001). Test–retest reliability was demonstrated in the instrument's subscale scores (ICC 0.70–0.90). Conclusion These results support the construct validity, discriminant validity, and reliability of the CSHQ‐RA as a measure that captures the impact of RA on patients' health‐related quality of life. |
