Juvenile idiopathic arthritis: new insights into classification, measures of outcome, and pharmacotherapy

Significant advances have taken place in recent years in our understanding of the aetiopathogenesis, management, and clinical outcome of juvenile idiopathic arthritis (JIA). Fundamental to this advancement has been international collaborative efforts of the clinical scientific community and all those involved in the multidisciplinary care of children and young people with JIA. A key factor has been facing the challenge of developing a robust classification system for JIA, a clinically very heterogeneous group of conditions. JIA illustrates the necessity of disease classification to enable scientific progress but also the iterative and evolving process this entails. What is emerging is the imperative to improve our understanding of the biologic and genetic basis of JIA to underpin classification systems. Growing emphasis is centered on improved holistic care and outcome of children and young people with JIA. The expectation of patients, their families, and clinicians is the goal of inactive disease, remission off treatment, and the health and psychosocial well-being of young people emerging into adulthood. Validated tools that reflect these challenges are being developed, including those measuring disease improvement, flare, remission and minimal disease activity, health-related quality of life, and composite scores of activity and damage. Clinical research networks have driven success in developing an evidence-base for the treatment of JIA. Randomized comparative trials have demonstrated the benefit of early use of intra-articular corticosteroid injections, and the importance of methotrexate as the first-line, disease-modifying antirheumatic drug in JIA. The introduction of biologic therapies has opened a major new epoch in the medical management of JIA, with recent trials published on etanercept, infliximab, adalimumab, abatacept, tocilizumab, and anakinra. This review focuses on recent advances in JIA, especially developments in its classification, validation of appropriate measures of holistic outcome, and the specific contribution of established and newer pharmacologic agents available for treating children and young people.