Juvenile Idiopathic Arthritis
The term juvenile idiopathic arthritis (JIA) has replaced the older name, juvenile rheumatoid arthritis, because the disease has no direct relationship with adult-onset RA. Girls are affected more often than boys by a 3:1 ratio. Age of onset tends to be younger for girls (1–4 years) than for boys (8–10 years), and JIA is somewhat less common in African American and Asian populations than in white populations. As with many other autoimmune disorders, the pathogenesis of JIA is unclear.
Although classification of JIA has always been challenging, the International League of Associations for Rheumatology divides JIA into w1the 5 categories shown in Table 9-1. Ocular involvement is most common in the oligoarticular group, less common in the polyarticular group, and least common in the systemic group. Patients with oligoarticular or polyarticular (especially RF-negative subtype) disease should be periodically screened for ocular involvement because it is often asymptomatic. Furthermore, a positive ANA in either of these 2 groups is associated with an increased risk of developing uveitis.
Systemic JIA may present with variable onset of intermittent fever, arthritis, macular skin rash, lymphadenopathy, hepatosplenomegaly, pericarditis, and pulmonary effusions. Although laboratory findings of elevated ESR, CRP, and thrombocytosis are usual, ANA and RF are rarely present. The arthritis can involve any number of joints. Ocular involvement is not typical for this form of JIA.
Table 9-1 International League of Associations for Rheumatology Classification of Juvenile Idiopathic Arthritis (JIA)
The last 2 subtypes, psoriatic arthritis and enthesitis-related arthritis, were added to help in categorizing patients who did not fit into more common entities. Uveitis can occur in both of these subtypes.
Excerpted from BCSC 2020-2021 series: Section 1 - Update on General Medicine. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.