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Table 1 Juvenile idiopathic arthritis subtypes show specific age ranges for disease onset

From: Network analysis and juvenile idiopathic arthritis (JIA): a new horizon for the understanding of disease pathogenesis and therapeutic target identification

Categories Characteristics % of total Onset age Sex ratio (F:M)
Systemic onset Arthritis and daily fever ≥ 3 days, accompanied by at least one of the following: evanescent (non-fixed) erythematosus rash, generalised lymph node enlargement, hepatomegaly or splenomegaly (or both), serositis 4–17 Throughout childhood 1:1
Oligoarticular Arthritis affecting 1–4 joints during the first 6 months of disease 27–60 Early childhood (peak 2–4 years) 5:1
 Persistent Arthritis affecting < 4 joints throughout the disease course 40   
 Extended Arthritis affecting > 4 joints after the first 6 months of disease 20   
Polyarticular Arthritis affecting > 5 joints during the first 6 months of disease    
 Rheumatoid factor positive Two or more positive tests for rheumatoid factor at least 3 months apart 2–7 Late childhood or adolescence (peak 12–14 years) 3:1
 Rheumatoid factor negative Tests for rheumatoid factor negative 11–30 Early peak 2–4 years and late peak 6–12 years 3:1
Juvenile psoriatic arthritis Arthritis and psoriasis, or arthritis and at least 2 of the following: dactylitis, nail pitting or onycholysis, psoriasis in first degree relative 2–11 Late childhood or adolescence 1:0.95
Enthesitis related arthritis Arthritis and enthesitis, or arthritis or enthesitis with at least 2 of the following: sacroiliac joint tenderness or inflammatory lumosacral pain (or both), HLA-B27 antigen positive, onset in boy over 6 years old, acute anterior uveitis, HLA-B27 associated disease in first degree relative 1–11 Early peak 2–4 years and late peak 6–12 years 1:7
Undifferentiated arthritis Arthritis that fulfils criteria in no specific category or meets criteria for more than one category 11–21   
  1. Adapted from Prince et al. [43]