Ankylosing Spondylitis Research Today is a free monthly online journal that collates and summarizes the latest research about Ankylosing Spondylitis, including details on diagnosis, treatment, symptoms, causes. | ||||||||
|
How do the EQ-5D, SF-6D and the well-being rating scale compare in patients with ankylosing spondylitis?Boonen A, van der Heijde D, Landewé R, van Tubergen A, Mielants H, Dougados M, van der Linden S Department of Internal Medicine, Division of Rheumatology, University Hospital Maastricht, PO Box 5800, 6202 AZ Maastricht, The Netherlands. aboo@sint.azm.nl 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. Published 21 May 2007 in Ann Rheum Dis, 66(6): 771-7.
© 2004-2008 Ankylosing Spondylitis Research Today. All Rights Reserved. |
| ||||||
