title: Patients with very early-onset systemic juvenile idiopathic arthritis exhibit more inflammatory features and a worse outcome.
abstract: OBJECTIVE
  Systemic juvenile idiopathic arthritis (SJIA) frequently leads to disability and damage. Predictive factors for a poor outcome include persistent systemic features and younger age at onset. We describe and analyze disease features in patients with early-onset (EO) SJIA (disease onset before age 18 mo) and compare them to patients with later-onset (LO) disease.
  
  
  METHODS
  Clinical features at onset, activity measures (occurrence of macrophage activation syndrome, remission), and outcome measures for disability [Childhood Health Assessment Questionnaire (CHAQ) ≥ 0.5] and damage [radiographic joint destruction, Juvenile Arthritis Damage Index (JADI) score, growth retardation] observed during followup were analyzed retrospectively in patients with SJIA followed for ≥ 3 years since disease onset.
  
  
  RESULTS
  In total 132 patients were included. SJIA started at age ≤ 18 months in 19 (14%) patients and at a later age in 113 (86%) children. At onset, serositis (p < 0.01) and hepatomegaly (p < 0.05) were more frequent in EO patients, who also exhibited lower hemoglobin levels (p < 0.03) and higher platelet counts (p < 0.03) than patients with LO. Macrophage activation syndrome occurred in 20 patients (11 EO and 9 LO; p < 0.0001). Remission was achieved by 49 patients (37%; 4 EO and 45 LO). At last visit, destructive hip disease (p < 0.04), growth retardation (p < 0.01), radiographic damage (p < 0.02), and disability (p < 0.04) were more frequent in patients with EO disease, who had higher JADI scores (p < 0.003).
  
  
  CONCLUSIONS
  Patients with EO exhibited a more aggressive and destructive disease course than patients with LO SJIA.
authors: Service of Immunology and Rheumatology, Hospital de Pediatría Prof. Dr. Juan P. Garrahan, Buenos Aires, Argentina. rrusso@garrahan.gov.ar
authors: Ricardo A G
authors: RA
authors: Russo
authors: María M
authors: MM
authors: Katsicas
mesh_terms: D000293:Adolescent; D000367:Age Factors; D017668:Age of Onset; D001171:Arthritis, Juvenile / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D002648:Child; D002675:Child, Preschool; D004185:Disability Evaluation; D018450:Disease Progression; D005260:Female; D006801:Humans; D007223:Infant; D007249:Inflammation; D008297:Male; D011379:Prognosis; D011859:Radiography; D012189:Retrospective Studies; D012720:Severity of Illness Index