Factors associated with improvement in disease activity following initiation of etanercept in children and young people with Juvenile Idiopathic Arthritis: results from the British Society for Paediatric and Adolescent Rheumatology Etanercept Cohort Study

Objectives. The objectives of this study were to investigate change in disease activity, and explore factors associated with response, in children with JIA over the initial year of etanercept treatment. Methods. This analysis included children with JIA starting etanercept in the British Society for Paediatric and Adolescent Rheumatology Etanercept Cohort Study. Response was assessed using change in juvenile arthritis disease activity score-71 (JADAS-71), an excellent response (ACR Pedi 90), and achieving minimal disease activity (MDA) at 1 year. Change in JADAS-71 was evaluated over time. Multivariable backward stepwise logistic regression was performed to identify factors associated with ACR Pedi 90 and MDA. Results. A total of 496 children were included. Over the first year, 17 stopped due to inefficacy, 9 due to adverse events and 7 for other reasons. One child stopped for remission. At 1 year, 74, 69 and 38% reached ACR Pedi 30, 50 and 90, respectively, and 48% had achieved MDA. Independent predictors of achieving ACR Pedi 90 at 1 year included shorter disease duration [odds ratio (OR) 0.91; 95% CI: 0.85, 0.97)], no concurrent oral corticosteroid use (OR 0.48; 95% CI: 0.29, 0.80) and history of uveitis (OR 2.26; 95% CI: 1.08, 4.71). Independent predictors of achieving MDA at 1 year included younger patients (OR 0.60; 95% CI: 0.38, 0.95), and disease not treated with concurrent oral corticosteroids (OR 0.57; 95% CI: 0.35, 0.93). Conclusion. Among this real-world cohort of children with severe JIA, a significant proportion of children achieved an excellent ACR Pedi response and MDA within 1 year of starting etanercept, although few clinical factors could predict this outcome.