Juvenile rheumatoid arthritis (JRA) may present as a systemic disease or as one affect- ing only the joints. Approximately 5% to 10% of children with JRA present with systemic signs, including fever, rash, pericarditis, or hepatosplenomegaly. These patients may have significant laboratory abnormalities, including leukocytosis and anemia. Although this form of disease can occur at any age, most cases are seen in patients younger than 10 years. The degree of joint involvement in this form of JRA can range from mild arthalgias to florid swelling of all joints. Children with this form of the disease appear acutely and gravely ill and may require hospitalization.
JRA is classified as pauciarticular when it affects four or fewer joints over the first 6 months of the disease and as polyarticular when more than four joints are affected. Both types present with joint swelling over a period of weeks to months. Girls with pauciarticular disease are at high risk for eye involvement (chronic uveitis); boys with this subtype may develop a spondyloarthropathy (spinal arthritis). In children with polyarticular disease, the presence of rheumatoid factor in the blood (found in about 20% of patients) is a risk factor for a more persistent and destructive arthritis.
Factors similar to those implicated in RA are thought to affect JRA as well. Specifically, genetic predisposition (HLA-DR4 in seropositive JRA, HLA-DR4 in pauciarticular type I, and HLA-B27 in pauciarticular type II), unknown environmental triggers, and immune reactivity are all thought to be possible causes. The inflammatory synovitis that is the hall- mark of JRA does not differ among subtypes and is generally more vascular than that seen in adults.
Diagnosis is made by the demonstration of persistent arthritis in one or more joints for a minimum of 6 weeks, the exclusion of other diagnoses and, in the case of systemic disease, the presence of either fever or rash.
Once the diagnosis of JRA is established, a therapeutic plan is devised based on the subtype and severity of disease. NSAIDs are standard initial therapy. In systemic disease, second-line agents such as hydroxychloroquine or methotrexate may be added early in the disease course; corticosteroids may be required for pericarditis or disease that is unresponsive to other therapies. Most children with pauciarticular disease will respond to an appropriate NSAID. Intra-articular corticosteroids may be needed, and occasion- ally second-line agents such as sulfasalazine are added. Patients with persistent, severe systemic or polyarticular disease who do not adequately respond to methotrexate therapy are candidates for treatment with anti-TNF drugs. Low-dose, short-term corticosteroid therapy may be needed. Long-term cortico- steroid use in children is avoided because steroids may cause growth retardation, iatrogenic Cushing’s disease, osteoporosis, fractures, and hypertension.
In addition to drug therapy, children with JRA must be carefully monitored for growth abnormalities, nutritional problems, and school and social dysfunction. Psychological and emotional health may be difficult to maintain in the presence of chronic disease. Therapeutic exercise programs can maximize joint motion and minimize muscle atrophy.