Update on juvenile rheumatoid arthritis

JRA is diagnosed when a child 16 years or less has arthritis in one or more joints for at least six consecutive weeks and other causes of arthritis are excluded. There is predominantly large joint involvement with frequent cervical spine involvement and children may present with contractures and atrophy of muscles. Subtypes of the disease are defined by clinical features in the first six months. Children with JRA may also have chronic uveitis, a positive ANA and only about 5-10% have a positive rheumatoid factor JRA is really at least five diseases lumped together under this heading. Systemic- onset JRA (15-20% of patients) presents with fever and rash, hepatosplenomegaly, lymphadenopathy, anemia, leukocytosis and thrombocytosis initially. Arthritis appears within a few months and systemic manifestations wane. Pauciarticular JRA (about 50% of patients, 4 joints or less initially) is the mildest form of JRA. It may be subtyped into early onset (young girls, often with chronic iritis), and late onset (boys, often with acute iritis and spondyloarthropathy). Polyarticular JRA (5 or more joints) can cause more permanent disability. It may be subtyped into rheumatoid factor negative and rheumatoid factor positive which has a much worse prognosis. First line therapy for JRA uses NSAIDs. With conscious sedation interarticular injection of corticosteroids may provide control without systemic medication. For second line therapy, methotrexate in low doses is very useful and has replaced other drugs, with good response in about 85% of patients. Third Line Therapy involves tumor necrosis factor receptor and has been shown to be effective in adults and is under study in children.