Growth Velocity and Interleukin 6 Concentrations in Juvenile Idiopathic Arthritis

Objective. To evaluate associations of growth velocity with inflammatory markers and cumulative dose of glucocorticoid in a cohort of patients with juvenile idiopathic arthritis (JIA) followed during I year. Methods. Seventy-nine patients were evaluated. Disease activity was evaluated by a pediatric rheumatologist. Anthropometric data were classified according to the World Health Organization standards. Tanner growth Velocity Curves were used; values below the Z-score <= -2 were considered low growth velocity. Serum concentrations of interleukin 6 (IL-6) were measured by ELISA, and values > 1 pg/ml were considered elevated. Results. The prevalence of low growth velocity was 25.3%, and it was associated with active disease on followup visit, elevated IL-6, erythrocyte sedimentation rate and C-reactive protein, and higher cumulative glucocorticoid doses. In the multiple linear regression with growth velocity as the dependent variable, only elevated IL-6 level was independently and negatively associated with growth velocity. Conclusion. Low growth velocity is highly prevalent in children with JIA. Elevated IL-6 levels seem to have an important negative influence on growth in these children, while total glucocorticoid exposure appears to be a secondary factor. (First Release Oct 1 2008; J Rheumatol 2008;35:2265-71; doi: 10.3899/jrheum.080199)