Quality-of-life assessment is receiving increased attention as an outcome measure in rheumatoid arthritis (RA). The most widely used instruments use variations on a vertical visual analog scale (VAS). Since the Health Assessment Questionnaire (HAQ), Arthritis Impact Measurement Scales (AIMS), and other instruments have long included a "global" arthritis horizontal VAS (GLOB), we studied whether these 2 approaches assess the same concept.
We studied 663 patients with RA from 4 ARAMIS (Arthritis, Rheumatism, and Aging Medical Information System) centers and had them complete, in different parts of the same HAQ, the GLOB and the Torrance "feeling thermometer" (FT).
The 2 scales were highly correlated (r = -0.676; p < 0.001). Reliability (estimated by 6 month test-retest) was 0.62 for the FT and 0.83 for the GLOB. The GLOB correlated more strongly than the FT with disability (r = 0.561 vs -0.507) and pain (0.630 vs -0.553). In stepwise regressions, pain and then disability were the dominant predictors of both GLOB and FT, followed weakly by joint count and then other variables. Patients with greater disability placed more emphasis on pain and patients with greater pain appeared to value more the contribution of disability. Change scores over 6 months between GLOB and FT correlated very well (-0.59).
"Health" and "health related quality-of-life" are nearly equivalent terms. Since large longitudinal rheumatology databases contain thousands of global health VAS values, data for longitudinal quality-of-life studies in arthritis are already available, and this dimension may readily be added to longterm outcome assessment. In patients with RA, "generic" and "disease specific" assessments yield very similar results.