The diagnosis of JIA is established by the presence of arthritis, the duration of the disease for at least 6 weeks, and exclusion of other possible diagnoses. Although a presumptive diagnosis of systemic-onset JIA can be established for a child during the systemic phase, a definitive diagnosis is not possible until arthritis develops. Children must be younger than 16 years of age at time of onset of disease; the diagnosis of JIA does not change when the child becomes an adult. Because there are so many other causes of arthritis, these disorders need to be excluded before providing a definitive diagnosis of JIA (Table 89-3). The acute arthritides can affect the same joints as JIA but have a shorter time course.
The treatment of JIA focuses on suppressing inflammation, preserving and maximizing function, preventing deformity, and preventing blindness. Nonsteroidal anti-inflammatory drugs (NSAIDs) are the first choice in the treatment of JIA. Naproxen, sulindac, ibuprofen, indomethacin, and others have been used successfully. Systemic corticosteroid medications, such as prednisone and prednisolone, should be avoided in all but the most extreme circumstances, such as for severe systemic-onset JIA with internal organ involvement or for significant active arthritis leading to the inability to ambulate. In this circumstance, the corticosteroids are used as bridging therapy until other medications take effect. For patients with a few isolated inflamed joints, intra-articular corticosteroids may be helpful.
Second-line medications, such as hydroxychloroquine and sulfasalazine, have been used in patients whose arthritis is not completely controlled with NSAIDs alone. Methotrexate, given either orally or subcutaneously, has become the drug of choice for polyarticular and systemic-onset JIA, which may not respond to baseline agents alone. Methotrexate can cause bone marrow suppression and hepatotoxicity; regular monitoring can minimize these risks. Leflunomide, with a similar adverse effect profile to methotrexate, has also been used. Biologic agents that inhibit TNF-α and block the inflammatory cascade, including etanercept, infliximab, and adalimumab, are effective in the treatment of JIA. The risks of these agents are greater, however, and include serious infection and, possibly, increased risk of malignancy. Anakinra, an interleukin-1 receptor antagonist, is very beneficial in the treatment of the systemic features of systemic-onset JIA.
Complications with JIA result primarily from the loss of function of an involved joint secondary to contractures, bony fusion, or loss of joint space. Physical and occupational therapies, professionally and through home programs, are crucial to preserve and maximize function. More serious complications stem from associated uveitis; if left untreated, it can lead to serious visual loss or blindness.
The prognosis of JIA is excellent, with an overall 85% complete remission rate. Children with oligoarticular JIA uniformly tend to do well, whereas children with polyarticular disease and systemic-onset disease constitute most children with functional disability. Systemic-onset disease, a positive
Juvenile idiopathic arthritis Systemic lupus erythematosus Juvenile dermatomyositis Scleroderma with arthritis
Leukemia Lymphoma Sickle cell disease Thalassemia Malignant and benign tumors of bone, cartilage, or synovium Metastatic bone disease Hemophilia
Rickets/metabolic bone disease Lysosomal storage diseases Heritable disorders of collagen rheumatoid factor, poor response to therapy, and the presence of erosions on x-ray all connote a poorer prognosis. The importance of physical and occupational therapy cannot be overstated because when the disease remits, the physical limitations remain with the patient into adulthood.