Development and Retrospective Validation of the Juvenile Spondyloarthritis Disease Activity Index

Abstract

Objectives To develop and validate a Juvenile Spondyloarthritis (JSpA) Disease Activity (JSpADA) index for use in clinical practice and research. Methods Using modified Delphi consensus techniques, ten items were selected by participants in the international pediatric rheumatology list-serve, the Childhood Arthritis and Rheumatology Research Alliance, and the list-serve for the Pediatric Section of the American College of Rheumatology. Validation was performed in a retrospective multicenter cohort of 243 children. Results 106 physicians representing 14 countries completed the initial questionnaire. Completion rates for the subsequent questionnaires were 84%, 75%, and 77% of the original respondents. Ten items reached 80% consensus: arthritis, enthesitis, patient pain assessment, inflammatory markers, morning stiffness, clinical sacroiliitis, uveitis, back mobility, and patient and physician assessments of disease activity. Two items were eliminated after item analysis (patient and physician assessments of disease activity). Factor analysis identified 3 primary domains that explain 58% of variance: peripheral disease, axial disease, and uveitis. Cronbach α coefficient was 0.66. The JSpADA had high or moderate correlations with the Juvenile Arthritis disease activity score (r=0.80), patient and physician assessments of disease activity (r=0.70 and 0.66), and the Childhood Health Assessment Questionnaire (r=0.56). The JSpADA discriminated well between subjects with active versus inactive disease (p<0.001) and was responsive to improvement or worsening in disease activity over time (p<0.001). Conclusion Using international input and consensus formation techniques, we developed and validated the first disease activity assessment for JSpA. Future studies should validate the JSpADA index in a prospective multi-center cohort.

Assessment of Sacroiliitis at Diagnosis of Juvenile Spondyloarthritis by Radiography, Magnetic Resonance Imaging, and Clinical Examination

“…The JSpA Disease Activity (JSpADA) index score was determined for all cases. (17) For this study the definition of inflammatory back pain was adapted from the Assessment of SpondyloArthritis international Society (ASAS) criteria (18) for adults and was defined as present when 3 criteria were present: 1) insidious onset, 2) improvement with exercise, 3) no improvement with rest, 4) pain at night (with improvement upon arising). Questionnaires were completed by a parent/guardian for subjects 12 years of age or younger.…”

Enthesitis-related arthritis

“…It includes eight parameters (objectively scored between 0 and 1): active joint count, active enthesitis count, visual analog scale for pain, morning stiffness greater than 15 min, inflammatory markers (ESR, CRP), presence or absence of clinical sacroiliitis, uveitis (acute or chronic), and restricted lumbar spine mobility measured by modified Schober's test. This needs prospective validation across different ethnic groups [44].…”

Juvenile Spondyloarthritis

“…HLA-B*27:05 is the most common subtype seen in JSpA (9). While HLA-B27 positivity is reported in more than 95% of adults with AS, recent JSpA studies demonstrate a lower prevalence of approximately 50% (10,11). Several theories regarding the role of HLA-B27 in directly or indirectly stimulating an inflammatory response include: 1) HLA-B27 misfolding, 2) HLA-B27 binding of arthrogenic peptides, and 3) HLA-B27 dimerization (12).…”

“…Cut-off values for defining remission, minimal disease and acceptable symptom state with the JADAS have been validated (62). The JSpA Disease Activity Score (JSpADA) is a continuous disease activity measure for children with JSpA that was retrospectively validated in a multicenter cohort of children (11). This index includes 8 items that are equally weighted and based primarily upon physician assessment (Table 3).…”