How do the EQ-5D, SF-6D and the well-being rating scale compare in patients with ankylosing spondylitis?. Issue 6 (9th January 2007)

• Record Type: Journal Article
• Authors: Boonen, Annelies; van der Heijde, Désirée; Landewé, Robert; van Tubergen, Astrid; Mielants, Herman; Dougados, Maxime; van der Linden, Sjef
• Is Part Of: Annals of the rheumatic diseases. Volume 66:Issue 6(2007)
• Page Start: 771
• Page End: 777
• Publication Date: 2007-01-09
• Subjects: ASQoL, Ankylosing Spondylitis Quality of Life -- BASDAI, Bath Ankylosing Spondylitis Disease Activity Index -- BASFI, Bath Ankylosing Spondylitis Functional Index -- EQ-5D, EuroQol—5 Dimensions -- ICC, intraclass correlation coefficient -- QALY, quality-adjusted life years -- QoL, quality of life -- RS, rating scale -- RTE, relative treatment effect -- SDD, smallest detectable difference -- SES, standardised effect size -- SF-36, Short-Form-36 -- SF-6D, Short-Form—6 Dimensions -- SG, standard gamble -- TTO, time-trade-off; Rheumatism -- Periodicals; 616.723005
• DOI: 10.1136/ard.2006.060384
• Languages: English
• ISSNs: 0003-4967

Abstract

Abstract : Purpose: To compare aspects of validity of EuroQol—5 Dimensions (EQ-5D) and Short-Form—6 Dimensions (SF-6D), two indirect utility instruments, and the well-being rating scale (RS) in ankylosing spondylitis (AS). Methods: EQ-5D, SF-6D and RS were available for 254 patients fulfilling modified New York criteria. 134 patients were part of an observational cohort and 120 were part of a randomised controlled trial (RCT). Aspects of validity assessed were truth (agreement and correlation with external health measures) and discrimination (differentiation between health states, repeatability and detection of treatment effect). Results: Median (range) values were 0.69 (−0.08–1.00) for the EQ-5D, 0.65 (0.35–0.95) for the SF-6D and 0.65 (0.14–1.00) for the RS. Agreement (intraclass correlation coefficient) was moderate (0.46–0.55). Instruments correlated equally with disease activity, functioning and quality of life. The SF-6D showed smaller average differences in utility between patients with better and worse disease compared with the EQ-5D and the RS. The smallest detectable difference (SDD) (in the control group of RCT) was 0.36, 0.17 and 0.33 for EQ-5D, SF-6D and RS, respectively. The ability to detect treatment effect (in the intervention trial) showed standardised effect sizes that were moderate for EQ-5D and SF-6D (0.63 and 0.64) and low for the RS (0.23). Conclusion: In patients with AS, EQ-5D, SF-6D and the RS correlate equally well with external measures of health, but have different psychometric properties. The SDD is most favourable for the SF-6D, but it discriminates less well between patients with different disease severities. The RS has a poorer ability to detect treatment effects. It is difficult to recommend one of the instruments.