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Sunday, 23 October 2005 - 2:15 PM

THE LONGITUDINAL ASSOCIATION BETWEEN OBJECTIVE CLINICAL MEASURES AND PATIENT SELF-REPORTING INFORMATION IN RHEUMATOID ARTHRITIS

Wietske Kievit, MSc1, Paco M.J. Welsing, MSc1, Eddy M.M. Adang, PhD1, Agnes M. Eijsbouts, PhD2, Paul F.M. Krabbe, PhD1, and Piet L.C.M. Van Riel, MD, PhD1. (1) Radboud University Nijmegen Medical Centre, Nijmegen, Netherlands, (2) Sint Maartenskliniek, Nijmegen, Netherlands

Background: Recently it was proposed to use patient self-reporting, subjective, information instead of clinical, objective, measurements to monitor patients with rheumatoid arthritis (RA). The use of subjective, self-reporting information assumes an association between objectively measured disease activity and the preferences about general health scored by patients. Purpose: to explore the association (in time) between disease activity and patient based preferences in rheumatoid arthritis (RA). Methods: Observational data of 624 newly diagnosed RA patients who completed 3 years of follow-up were used for analyses. The disease activity score (DAS28), a statistically derived index combining joint counts for swelling and tenderness and the Erythrocyte Sedimentation Rate (an acute phase reactant), was used as a objective measure of RA disease activity. A visual analogues scale (VAS) was used as a subjective measure for general health as perceived by the patient. Linear regression models were performed with the VAS as outcome variable and the DAS28 as independent variable at 3-monthly time points. The regression model at time=0 (diagnosis) was used to predict the VAS at the other time points and plotted against the observed VAS. Longitudinal regression analysis (general linear mixed model) was used to develop an overall model for the relation between VAS and DAS28 over first 3 year of the disease. Results: The DAS28 and the VAS were significantly associated in RA patients at all time points. However, the explained variance was low (r2=0.07). The intercept of the regression models decreased over time in combination with a similar coefficient for the relation between DAS28 and VAS. The observed general health diverged (became better) compared to the predicted general health over the course of the disease. The longitudinal regression model showed that time was an independent significant factor, indicating that the general health improved over the disease course independent of changes in DAS28. Conclusions: There is an association between subjective patient self-reporting information and objective clinical measures. However, it was shown that later in the disease course the patients' preference of her health state on average was better given the same disease activity as compared to shortly after diagnosis. Preferences seem to be unstable in time. Therefore patient based information may lead to different treatment decisions then information based on clinical measurements.

See more of Oral Concurrent Session J - Measurement of Health Status and Preferences
See more of The 27th Annual Meeting of the Society for Medical Decision Making (October 21-24, 2005)