Juvenile Spondyloarthritis Disease Activity Index Valid in Children With Enthesitis-Related Arthritis

The Juvenile Spondyloarthritis Disease Activity Index (JSpADA) is an appropriate measure of disease activity for enthesitis-related arthritis, according to study results published in Rheumatology.

Researchers sought to prospectively validate the JSpADA as a measure of arthritic activity. Children (<18 years) with enthesitis-related arthritis (n=127) completed a baseline visit that assessed disease activity using both JSpADA and existing validated measures, including the Bath Ankylosing Spondylitis Disease Activity Index, the Ankylosing Spondylitis Disease Activity Score using erythrocyte sedimentation rate, and the 10-joint Juvenile Arthritis Disease Activity Score. Physician and patient global assessment were recorded at baseline, and a Childhood Health Assessment Questionnaire was completed. The mean age among study participants was 14.3 ± 2.4 years, and 116 (91.3%) were boys. The average disease duration at baseline was 36.9 ± 3.0 months, and 107 patients (84.3%) had active disease.

The JSpADA strongly correlated with physician global assessment, patient global assessment, 10-joint Juvenile Arthritis Disease Activity Score, and Childhood Health Assessment Questionnaire score (P <.0001 for all). Mean JSpADA scores differed between patients with active and inactive disease (P <.0001), suggesting high discriminative capacity. Among those who completed a second visit and reported changes in disease activity, mean change in JSpADA was significantly different between those who improved and those who worsened (P <.0001). In addition, JSpADA also demonstrated high sensitivity to change. In 15% of patients, back mobility could not be assessed because of active arthritis in the lower limbs; the JSpADA excluding back mobility performed just as well as the original JSpADA.

These results validate the JSpADA in a prospective cohort and confirm its strength as a measure of disease activity for enthesitis-related arthritis. Additionally, the high performance of JSpADA when excluding back mobility measures suggests its high applicability to children with active lower limb arthritis, although this hypothesis necessitates further research.

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Reference

Zanwar A, Phatak S, Aggarwal A. Prospective validation of the Juvenile Spondyloarthritis Disease Activity Index in children with enthesitis-related arthritis [published online August 9, 2018]. Rheumatology (Oxford). doi: 10.1093/rheumatology/key246