Background Axial and peripheral involvement, enthesitis and positive HLAB27 in 60-90% children are main features of juvenile spondyloarthritis (JSpA). Radiological sacroiliitis represents an important prognostic factor that may occur within 10 years from onset.

Objectives To determine initial and long term clinical profiles of Brazilian patients with JSpA from a single tertiary university center; the prevalence of HLAB27 and correlation with disease progression to ankylosing spondylitis (AS), according to ASAS criteria.

Methods Descriptive cross-sectional study of a cohort of JSpA patients. All clinical demographic and radiological data were collected from chart review and HLA-B27 was analysed by flow cytometry (Becton Dickinson). Fisher and McNemar's tests were used for statistical analyses and p<0.05 considered significant.

Results Fifty patients with JSpA were assessed, with mean age=31.5±11.1yrs (15-60), mean age at.2±2.73yrs (7-16), mean age at diagnosis=19.8±9.0yrs (7-44) and mean disease duration=18.9±11.4yrs (3-44). The majority were males (44M:6F,88%) and whites (n=42,84%). Eleven (22%) subjects had a 1st-degree relative with SpA and 87% (34/39) were HLAB27+. At diagnosis (Table), peripheral manifestations was predominant, particularly asymmetric oligoarthritis while axial involvement was mainly inflammatory back and buttocks pain; 21 (42%) had enthesitis, all at the Achilles insertion; anterior uveitis was the major extra-articular manifestation. After a mean follow up period of 12.8±9.13yrs (1-45), 5 patients were lost, axial involvement prevailed, enthesitis remained in 13/21 and none had uveitis (Table). Radiological sacroiliitis developed in 96% (n=48) patients: 42% (n=20) ≤5yrs, 17% (n=8) within 6-10yrs and 42% (n=20) >10yrs of initial symptoms. Of note, HLA-B27+ children had earlier sacroiliitis ≤5yrs from diagnosis (p=0.02), high ESR at diagnosis (p=0.04) and developed AS (p=0.02). Regardless of daily NSAIDs therapy intake by all patients, sacroiliitis progression was not prevented (p>0.05). Sulfasalazine was used by 86% and MTX by 72%, and currently 49% patients are on anti-TNF drugs.

Conclusions Brazilian JSpA patients are characteristically white males with initial peripheral joint and enthesitic manifestations that develop axial disease. The high prevalence of HLAB27+ in JSpA associated to early sacroiliitis, elevated ESR at diagnosis and progression to AS strengthen its role as a genetic marker of disease severity in children.

Disclosure of Interest None declared