Juvenile Spondyloarthritis Disease Activity Index Validation in Enthesitis-Related Arthritis and Juvenile Psoriatic Arthritis in a Prospective Clinical Trial Setting.

Abstract

To investigate the validity of the Juvenile Spondyloarthritis Disease Activity Index (JSpADA) in children with enthesitis-related arthritis (ERA) or juvenile psoriatic arthritis (jPsA) in a prospective clinical trial setting. JUNIPERA (ClinicalTrials.gov: NCT03031782) is a phase III, placebo-controlled withdrawal study investigating the safety and efficacy of secukinumab in children with ERA and jPsA. After 12 weeks of open-label treatment with secukinumab, patients were randomized 1:1 to secukinumab or placebo until disease flare or week 52. JSpADA validity was assessed using 3 criteria: convergent validity (Spearman correlation) at week 12 with the Juvenile Arthritis Disease Activity Score in 10 joints (JADAS10), clinical JADAS10 (cJADAS10), and physician global assessment of disease activity (PGA); discriminatory validity at week 12 among patients with active or inactive disease and juvenile idiopathic arthritis American College of Rheumatology response criteria; and responsiveness to change in clinical disease activity from weeks 12 to 52. At week 12, mean (SD) JSpADA scores showed moderate to good correlation with JADAS10, cJADAS10, and PGA scores (all Spearman ρ > 0.4) and were higher among patients with active vs inactive disease (1.8 [1.3] vs 0.5 [0.8], <i>P</i> < 0.001). Patients with improved disease activity from weeks 12 to 52 had greater improvements in JSpADA than patients with worsening disease (-0.8 [1.1] vs 0.4 [1.0], <i>P</i> < 0.001); patients with stable disease had minimal change in JSpADA (-0.1 [0.5]). Validity results were similar for ERA and jPsA. These results validate JSpADA as a disease activity measure for children with ERA and jPsA in a prospective clinical trial setting.