Psychometric characteristics of outcome measures in juvenile idiopathic arthritis: a systematic review

To review the performance characteristics of the instruments most commonly used to measure clinical outcomes in juvenile idiopathic arthritis (JIA), including global assessments, articular indices, functional/disability assessments, and quality of life measures.

As part of an Agency for Healthcare Research and Quality comparative effectiveness review of antirheumatic drugs, we explored the characteristics of commonly used outcome measures for JIA. English-language studies of children with JIA were identified from Medline and Embase. Two independent reviewers screened titles and abstracts, with subsequent full-text review of studies selected based on predetermined criteria.

We included 35 publications describing 34 unique studies and involving 14,831 patients. The Childhood Health Assessment Questionnaire (C-HAQ) was the most extensively studied instrument and had high reliability, but only moderate correlations with other indices of disease activity and poor responsiveness to change in disease status. The physician global assessment of disease activity (PGA) and articular indices had the strongest association with disease activity and were the most responsive to change. Measures of psychosocial function and quality of life were moderately associated with measures of disease activity, but were less responsive to changes in disease status.

In children with JIA, no single instrument was superior in reliability or validity or in describing the impact of JIA. Although the C-HAQ has been extensively evaluated, the PGA and articular indices appear to have the highest responsiveness to change and, therefore, the highest potential for detecting important differences in treatment response.