Types of juvenile idiopathic arthritis

International League of Associations for Rheumatology (ILAR) has proposed the following criteria which classifies JIA into 7 heterogeneous subgroups

• oligoarticular
  • no more than four affected joints in the first six months of disease
  • 27–56% of JIA cases
  • F>M
  • often antinuclear antibody (ANA) positive. Strong association with anterior uveitis
• polyarticular – RF negative
  • more than four affected joints in the first six months of disease; RF negative
  • 11–28% of JIA cases
  • F>M
  • often symmetric involvement of small, medium and large joints
• polyarticular – RF positive
  • more than four affected joints in the first six months of disease; RF positive on two separate occasions
  • 2–7% of JIA cases
  • F>M
  • closely related to rheumatoid arthritis with similar phenotypic and prognostic features; classically affects adolescent girls
• enthesitis-related arthritis
  • arthritis, enthesitis – tends to involve axial and weight-bearing joints including SIJ
  • 3–11% of JIA cases
  • M>F
  • the juvenile spondyloparthropathy, often HLA-B27 positive males
• psoriatic arthritis
  • arthritis, psoriasis
  • 2–11% of JIA cases
  • F>M
  • also associated with dactylitis and nail changes such as pitting, ridging, onycholysis
• systemic onset
  • fever, rash, arthritis (‘Still’s disease’); may have hepatosplenomegaly, lymphadenopathy
  • 4–17% of JIA cases
  • F>M
  • can develop life-threatening immune dysregulation known as macrophage activation syndrome
• undifferentiated
  • arthritis that does not meet criteria for other JIA subtypes
  • 11–21% of JIA cases

Reference:

• (1) James RA, Wedderburn LR. Modern management of juvenile idiopathic arthritis. Prescriber. 2016; 27: 37–43