Background/Purpose: Herein we describe characteristics of children with juvenile spondyloarthritis (JSpA, i.e. enthesitis-related arthritis [ERA] or juvenile psoriatic arthritis [JPsA]) enrolled in the Childhood Arthritis and Rheumatology Research Alliance (CARRA) Registry, which was established in 2015.

Methods: All children with physician-diagnosed ERA or JPsA enrolled in the CARRA Registry between June 2015 and June 2018 were identified.  Demographics, clinical characteristics, and treatments of children with ERA and JPsA were described and contrasted.  Additionally, children with JSpA and sacroiliitis were compared to those without sacroiliitis.  Finally, in the group with sacroiliitis, the first visit with clinically active sacroiliitis was compared to the first visit without clinically active sacroiliitis.  ‘Clinical sacroiliitis’ was at the discretion of the treating physician and sacroiliitis by imaging was diagnosed by MRI, X-ray, and/or CT.

Results: Nine hundred two children with JSpA – 522 (58%) with ERA and 380 (42%) with JPsA – were identified.  Children with ERA were older at diagnosis (10.8 versus 8.2 years) and more likely to be male (56% versus 38%).  Polyarticular involvement (ever) was reported in 56% of children with ERA and 71% of those with JPsA.  Sacroiliitis (ever, by imaging and/or clinical exam) was reported in 40% of those with ERA versus 12% of those with JPsA.  Enthesitis was reported in 78% of children with ERA and 18% of those with JPsA.  HLA-B27 was positive in 24% of those with ERA and 7% of those with JPsA (see Table 1 for comment on missing data).  At least one biologic was taken by 72% of those with ERA and 64% of those with JPsA (Table 1), mostly TNF inhibitors.

Twenty-eight percent of the children with JSpA had sacroiliitis (by imaging and/or clinical diagnosis).  Of the children with JSpA who had sacroiliitis, 54% were female, while 50% of those without sacroiliitis were female.  Of those with sacroiliitis, 34% were positive for HLA-B27 versus 21% of the children without sacroiliitis (see Table 2 for comment on missing data).  Of those with sacroiliitis, 81% took at least one biologic during follow-up versus 65% of those without sacroiliitis (Table 2).

In those with sacroiliitis, the first visit with active sacroiliitis was compared to the first visit without sacroiliitis.  At the active visit, the physician global assessment, parent/patient global, active joint count, and cJADAS 10 were all significantly worse.  However, there was no significant difference between visits in the physical function, CHAQ, or pain measures (Table 3).

Conclusion: In the CARRA Registry, there are currently over 900 children with physician-diagnosed JSpA.  There are clear phenotypic differences between the children with ERA versus those with PsA.  There was high biologic use, especially TNF inhibitors, in this population.  It was particularly high in those with sacroiliitis.  Further, there was equal sex representation in those with sacroiliitis.

Table 1_JSpA ACR Abstract 2019

Table 2 – JSpA ACR Abstract 2019

Table 3 – JSpA ACR Abstract 2019

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/juvenile-spondyloarthritis-in-the-childhood-arthritis-and-rheumatology-research-alliance-carra-registry-high-biologic-use-low-prevalence-of-hla-b27-and-equal-sex-representation-in-those-with-sacr/