Arthritis, Juvenile Idiopathic

Basics

Previously called juvenile rheumatoid arthritis (JRA) with the addition of other idiopathic arthritis of childhood
Juvenile idiopathic arthritis (JIA) comprises persistent, unexplained arthritis lasting >6 wk, occurring <17 yr of age, and affecting a heterogeneous group of children
Prevalence 44 in 100,000 children in North America
Caucasians > African American and Asian populations
Girls > boys for most forms
Peak incidence 11–15 yr of age
Classified into 7 subgroups: Systemic onset, polyarticular RF+, polyarticular RF–, oligoarticular (pauciarticular), psoriatic, enthesitis, other or unclassified
Subtypes are based on number, type, and symmetry of joints involved; presence of systemic symptoms; skin involvement; family history; and lab values
Up to 20% of JIA patients remain unclassified or are classified in multiple categories
Natural course of the disease depends on the subtype – oligoarticular most likely to achieve remission; polyarticular RF+ least likely
Full resolution occurs in ∼50% of JIA patients
Many will have a fluctuating course and ongoing disease through adulthood

Believed to be an autoimmune and autoinflammatory disease triggered by an unknown environmental trigger in a genetically susceptible host

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