Responsiveness of outcome measures in juvenile chronic arthritis. Italian Pediatric Rheumatology Study Group

To examine the responsiveness of the disease activity measures more commonly used in juvenile chronic arthritis (JCA) clinical trials. Data were obtained from an open-label, non-controlled, multicentre trial designed to investigate the efficacy of methotrexate (MTX) in children with JCA. Outcome measures, including physician and parent global assessments, functional ability measures, articular variables, and laboratory indicators of systemic inflammation, were assessed at baseline and after 6 months of MTX treatment in 132 patients. Responsiveness of endpoint variables was evaluated by assessing the effect size (ES) and the standardized response median (SRM). Physician and parent global assessments were the more responsive instruments, showing ES and SRM above 1.0. Erythrocyte sedimentation rate, C-reactive protein, functional status measures and articular variables showed intermediate responsiveness. Morning stiffness, haemoglobin and platelet count were the least responsive instruments. The results of our analysis indicate that subjective estimations of the disease activity, either by the physician or parents, are the most responsive instruments in the assessment of the therapeutic response in children with JCA. The responsiveness of outcome measures in JCA should be further investigated in prospective controlled studies.