JSpADA passes disease measure validation for enthesitis-related, juvenile psoriatic arthritis

A post hoc analysis of the JUNIPERA study has validated the Juvenile Spondyloarthritis Disease Activity Index (JSpADA) as a disease measure for children with enthesitis-related arthritis (ERA) and juvenile psoriatic arthritis (jPsA) in a prospective clinical trial setting, discriminating between active and inactive disease.

Furthermore, JSpADA correlated with other validated disease activity measures and responds to changes in clinical disease activity in children with ERA and jPsA.

JUNIPERA, a phase III, placebo-controlled withdrawal study, examined the safety and efficacy of secukinumab in children with ERA and jPsA. After 12 weeks of open-label treatment, the investigators randomized patients 1:1 to receive either secukinumab or placebo until disease flare or week 52.

Three criteria were used to assess the validity of JSpADA: convergent validity 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.

The mean JSpADA scores at week 12 demonstrated moderate to good associations with JADAS10, cJADAS10, and PGA scores (Spearman ρ>0.4 for all) and were higher among children with active disease than those with inactive disease (1.8 vs 0.5; p>0.001). [J Rheum 2026;53:85-94]

Notably, paediatric patients who had improved disease activity from weeks 12 to 52 showed a reduction in JSpADA scores, while those who with a worsening disease had an increase in scores (–0.8 vs 0.4; p<0.001). The change in JSpADA was minimal (–0.1) among children with stable disease. Validity results were comparable for ERA and jPsA.

“Overall, these results demonstrate that JSpADA is a valid measure of disease activity for paediatric patients with juvenile idiopathic arthritis (JIA),” the investigators said.

“Disease measures currently used to accurately assess JIA in children, including children with jPsA and ERA, may not reliably capture overall disease activity because current JIA metrics are heavily weighted toward peripheral joint activity, whereas the majority of children with ERA have oligoarticular disease (< 4 peripheral joints) or no peripheral disease at all,” they added. [Rheumatology 2013;52:1941-1951]

Enthesitis

Moreover, disease activity measures used for adult patients with spondyloarthropathies tend to underestimate key features of juvenile spondyloarthropathies, such as enthesitis, or are not validated for paediatric patients with spondyloarthropathies. [Front Med 2021;8:681621]

The JSpADA, on the other hand, assesses disease features that are central to ERA and jPsA, such as enthesitis and axial disease, and that are responsive to treatment. This allows the therapeutic response in patients to be properly evaluated.

"In this analysis, active enthesitis count and morning stiffness were two of the JSpADA components most responsive to treatment, emphasizing the importance of incorporating these measures when evaluating disease activity,” the investigators said. 

“Finally, there can be wide variation in how paediatric rheumatologists score certain disease measures such as PGA,” they added. [Rheumatology 2023;62:3421-3426]