Background Disease activity has been assessed by different tools in Rheumatoid Arthritis (RA) by Disease Activity Score – DAS 28 and Juvenile Idiopathic Arthritis (JIA) by Juvenile Arthritis Disease Activity Score – JADAS, the last scoring 71, 27 and 10 joints respectively. Reduced joint count was proposed for both tools based on compromising comprehensiveness and feasibility and by selecting most frequently affected joints. DAS 28 omits lower extremity joints.
Objectives Explore equivalence of DAS28 and JADAS in children and adolescents with JIA.
Methods 178 observations at regular intervals in 8 subjects enrolled in a placebo-controlled clinical trial were examined retrospectively for scoring disease activity with standardized joint count (28, 71, 27, 10), physician global assessment by visual analog scale (VAS 0-10), global assessment by patients/parents (VAS 0-10) and erythrocyte sedimentation rate (ESR) normalized to 0-100 scale. DAS-28 was calculated by formula. JADAS was obtained by direct sum of each component. Paired observations of DAS 28 and JADAS 71, 27 and 10, respectively were analysed by linear regression after conversion to logarithmic scale.
Results Linear regression for adjustment of DAS and JADAS indicated partial overlap. Along a mean follow up of 18 months a consistent overlap of JADAS 71, 27 and 10 was observed. Although direct score comparison of DAS28 and JADAS cannot be performed, a formula to transform both was obtained: DAS 28 = 1.263 × Log n (JADAS 71) – 1.267 (r2=0.81); DAS 28 = 1.288 × Logn (JADAS 27) – 1.297 (r2=0.80) e DAS 28 = 1.285 × Logn (JADAS 10) – 1.281 (r2=0.76).
Conclusions Partial overlap and scoring conversion may provide alternative use for adolescents and young adults with either RA or JIA.
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Disclosure of Interest None Declared
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