Final validation of a new composite disease activity score for juvenile idiopathic arthritis: the Juvenile Arthritis Disease Activity Score (JADAS)

Materials and methods The JADAS is composed of the following measures: 1) physician's global assessment (0–10); 2) parent's global assessment (0–10); 3) active joint count (assessed in 71, 27 or 10 joints); 4) ESR (normalized to 0–10). It yields a score ranging from 0 to 40, 57 or 101, depending on whether the whole 71-joint count (JADAS-71) or the 27joint (JADAS-27) or 10-joint (JADAS-10) reduced counts are used. The 3 versions of the JADAS were tested on juvenile idiopathic arthritis patients included in 2 trials on methotrexate (n = 595) and meloxicam (n = 225). Construct validity was assessed by calculating Spearman's correlation between baseline-endpoint changes in JADAS, CHAQ and 2 adult scores (DAS28, CDAI). Discriminative validity was assessed by examining the ability of JADAS to discriminate between different levels of ACR Pediatric response in the 2 trials.