A new analysis from the JUNIPERA trial has validated the Juvenile Spondyloarthritis Disease Activity Index (JSpADA) as a clinically appropriate tool for assessing disease activity in pediatric patients with enthesitis-related arthritis (ERA) and juvenile psoriatic arthritis (jPsA).
The analysis, conducted post hoc from the phase III, placebo-controlled JUNIPERA trial, evaluated the validity of JSpADA using three predefined metrics: correlation with existing disease activity measures (convergent validity), ability to differentiate between active and inactive disease (discriminatory validity), and sensitivity to clinical change over time (responsiveness). The study included 86 patients aged 2 to under 18 years with ERA or jPsA who received at least one dose of the IL-17A inhibitor secukinumab.
At week 12, JSpADA scores demonstrated statistically significant correlations with the Juvenile Arthritis Disease Activity Score in 10 joints (JADAS10), the clinical JADAS10 (cJADAS10), and the physician global assessment (PGA). Spearman correlation coefficients were 0.72 for JADAS10, 0.68 for cJADAS10, and 0.62 for PGA, indicating moderate to good alignment with these established tools.
JSpADA scores also distinguished between disease states. At week 12, patients classified with active disease had a mean JSpADA score of 1.8 compared to 0.5 in those with inactive disease (P < 0.001). Additionally, patients who achieved higher levels of clinical improvement—such as JIA ACR100—had larger reductions in JSpADA scores from baseline than those with lower levels of improvement.
The analysis also evaluated change in JSpADA scores from week 12 to week 52, during which patients either continued secukinumab or received placebo. Those with improved disease activity showed a mean decrease in JSpADA of –0.8, while those with worsening disease activity had a mean increase of 0.4 (P < 0.001). Patients with stable disease activity had minimal changes in score.
JSpADA consists of eight equally weighted components: active joint and enthesitis counts, patient-reported pain, C-reactive protein (CRP), morning stiffness, clinical sacroiliitis, uveitis, and spinal mobility. These components are designed to capture key features of ERA and jPsA that may not be fully represented in other JIA assessment tools.
According to the study authors, existing tools such as JADAS and PGA may emphasize peripheral joint activity and may not fully reflect disease burden in patients with enthesitis or axial symptoms. In this analysis, active enthesitis count and morning stiffness were among the most responsive components within JSpADA, suggesting their relevance in treatment monitoring.
Limitations of the study include its focus on children with at least three active joints, which may not represent patients with milder or predominantly axial disease. Additionally, because all participants received open-label secukinumab during the initial 12-week period, early treatment effects could have influenced the discriminatory performance of the index. Despite these constraints, the measure was able to detect clinically relevant differences in disease activity.
The authors concluded that JSpADA met key criteria for a valid outcome measure in pediatric populations with ERA and jPsA. The tool may offer clinicians an additional option for assessing disease activity in clinical trials and potentially in routine care. Further studies in broader populations are warranted to confirm generalizability across the full spectrum of juvenile spondyloarthritis.