Risk factors for an unfavorable outcome in juvenile idiopathic arthritis: retrospective study in Croatia

Summary: Introduction: Juvenile idopathic arthritis (JIA) is a chronic inflammatory disease with incidence from 2 to 20 per 100, 000 population. It is one of the more frequent chronic illnesses of children and important cause of longterm disability, but may also remit with no or minor sequelae. The aim of our study was to identify risk factors for an unfavorable outcome in children with JIA. Patients and methods: One hundred ninety-eight children with JIA, first admitted to the Department of Paediatric Rheumatology, University Hospital Zagreb, Croatia, between January 1990 and November 1995 were examined after 7 to 12 years (median 8.4) of disease duration. Clinical examination, laboratory variables (ESR, platelets, hemoglobin, ANA, HLA-B27 and radiographs of affeceted joints were obtained. Results: At disease onset, from 198 children with JIA, 104 were female (52, 6%) and 94 male (47, 4%). One hundred twenty six patients (63, 6%) had oligoarticular type (96 (48, 4%) persistent and 30 (15, 2%) extended subtype), 52 patients (26, 3%) had polyarticular type (15 (7, 6%) RF-negative and 37 (18, 7%) RF-positive), and 20 patients (10, 1%) had systemic type (Table 1 and 2).Within a median of 8.4 years of disease duration 31 patients (39, 3%) had oligoarticular type (12 (15, 2%) persistent and 19 (24, 1%) extended subtype), 44 patients (55, 7%) had polyarticular type (15 (18, 9%) RF-negative and 29 (36, 8%) RF-positive), and 4 patients (5.0%) had systemic type (Tables 1, 2, 3 and 4). At follow up, 119 patients (60, 1%) were in remission, 47 (23, 7%) had developed joint erosions, and 32 (16, 2%) had different functional disabilities, which required orthopedic prostheses or in some cases operation. The remission rate was higher in the patients with persistent oligoarticular than in those with extended oligoarticular and RF positive polyarticular JIA (Table 2.). Conclusion: In our study early risk factors for an unfavorable outcome were young age at onset, female sex, symmetric arthritis (polyarthrtitis), early hip joint involvement, early joint erosions, elevated ESR, positive RF and HLA-B27. The presence of uveitis in oligoarticular onset JIA didn’ t show like unfavorable prognostic factor, like was suggested in some studies