FRI0024 Contribution of the Individual Components of the Disease Activity Score (DAS28) to the Total DAS28 Score among Responders and Non-Responders to Biological Therapy for Rheumatoid Arthritis

Background The commonly used Disease Activity Score based on 28 joints (DAS28) is a composite index composed of two somewhat subjective components (tender joint count and visual analogue scale general well-being) and two more objective components (swollen joint count and erythrocyte sedimentation rate). However, not all individual components of DAS28 might respond similarly to treatment. Furthermore dominance of subjective over objective components in DAS28 at start of therapy might predict less effect of therapy. This subjective contribution relative to the total DAS28 was quantified through the “contribution score” (the subjective part of the DAS28 formula divided by the total DAS28 formula). Objectives First, to investigate if the contribution score of the study population changes over time between starting a first biological (baseline) and after three months of biological use, and to establish if this change is seen and similar in the non-, moderate- and good response to treatment groups. Second, to investigate if the subjective contribution at baseline is predictive of response to treatment at three months. Methods Patients included in this study were selected from two databases of the Utrecht Arthritis Cohort study group. In the CAMERA-II trial early RA patients had been included, comparing the addition of 10mg/day of prednisone or prednisone-placebo to a two-year MTX-based tight –controlled strategy, including a final step of adding a biological. In the more recent Utrecht observational Biological cohort study, any patient with RA who started a biological could be entered. A total of 51 of the CAMERA-II trial database patients and 121 of the Biological cohort study database, all starting a biological treatment, were included. To address the first objective, ANOVAs and paired t tests were performed. To address the second objective, an ordinal logistic regression analysis was performed (correcting for age, DAS28 at the start of the biological therapy, number of prior DMARDs used, cohort, gender, RF-status and smoking), with as criterion variable EULAR response (3 levels: non-, moderate- and good response) and as predictor variable the contribution score. Results Overall, a significant decrease in contribution score was observed (p