A critical appraisal of radiographic scoring systems for assessment of juvenile idiopathic arthritis.

Assessing structural damage to joints over time is essential for evaluating the effectiveness of therapeutic interventions for patients with inflammatory arthritis. Although radiography is able to quantify joint damage, the changes found with conventional radiography early in the disease course are nonspecific, and late radiographic changes are often irreversible. Although many clinical trials on drug development for children still use radiographic scales as endpoints for the study, more specific therapies have been developed for juvenile idiopathic arthritis (JIA) that would enable imaging to "fine-tune" patients to placement into specific treatment algorithms. As a result, new imaging scales to identify early abnormalities are clearly needed. Many pediatric rheumatology centers around the world persistently apply adult-designed radiographic scoring systems to evaluate the progression of JIA. Few pediatric-targeted radiographic scales are available for assessment of progression of JIA in growing joints, and the clinimetric and psychometric properties of such scales have been poorly investigated. We present a critique to the evaluative, discriminative, and predictive roles of the van der Heijde modification of Sharp's radiographic method, a scale originally designed to assess damage to joints of adults with rheumatoid arthritis, when it is applied to a pediatric population. We discuss the advantages and drawbacks of this radiographic scoring system for assessing growing joints and the ability of MRI to overcome inadequacies of conventional radiography.