AB1127

EQUIVALENCE OF DISEASE ACTIVITY TOOLS FOR JUVENILE IDIOPATHIC ARTHRITIS

R. C. Capela ¹C. Saad-Magalhaes ^1,*

¹Paediatrics, Botucatu Medical School, Botucatu, Brazil

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 x Log _n (JADAS 71) - 1.267 (r²=0.81); DAS 28= 1.288 x Log _n (JADAS 27) – 1.297 (r²=0.80) e DAS 28= 1.285 x Log _n (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.

References: Consolaro A. et al. Development and validation of a composite disease activity score for juvenile idiopathic arthritis. Arthritis Rheum 2009, 61:658.

Jansen J , van Riel PLCM The disease activity score and the EULAR response criteria. Rheum Dis Clin N Am 2009, 35: 745.

Landewé R et al. Twenty-eight joints count invalidate DAS the 28 remission definition owing to the omission of the lower extremity joints: a comparison with the original DAS remission. Ann Rheum Dis 2006, 65: 637.

Disclosure of Interest: None Declared