pediatrics
Juvenile Idiopathic Arthritis (JIA)
Classification of JIA
Juvenile idiopathic arthritis is not a single disease; the term applies to a number of chronic, noninfectious arthritides that occur in children and share certain features. The current classification system, from the International League of Associations for Rheumatology, defines categories of disease based on clinical and laboratory findings ( Classification reference ). Some of the categories are subdivided into different forms. Categories include the following: Oligoarticular JIA (persistent or extended) Polyarticular JIA (rheumatoid factor [RF] negative or positive) Enthesitis-related arthritis Psoriatic JIA Undifferentiated JIA Systemic JIA Many of these categories likely include more than one disease but are useful to help group children with a similar prognosis and response to treatment. Also, children sometimes move to different categories during the course of their illness. Oligoarticular JIAis the most common form and typically affects young girls. It is characterized by involvement of≤4 joints during the first 6 months of disease. Oligoarticular JIA is further divided into 2 types: persistent (always≤4 joints involved) and extended (≥ 5 joints involved after the first 6 months of disease). Polyarticular JIAis the second most common form. It affects≥5 joints at onset and is divided into 2 types: RF negative and RF positive. Typically, young girls are RF negative and have a better prognosis. The RF-positive type typically occurs in adolescent girls and is analogous to adult rheumatoid arthritis. In both types, arthritis can be symmetric and frequently involves the small joints. Enthesitis-related arthritisinvolves arthritis and enthesitis (painful inflammation at the insertion of tendons and ligaments). It is more common among older boys, and these patients may subsequently develop arthritis of their axial skeleton (sacroiliac and lumbar spine). Enthesitis-related arthritis tends to be in the lower extremities and asymmetric. The human leukocyte antigen–B27 (HLA-B27) allele is more common in this form of JIA. has a bimodal age distribution. One peak occurs in young girls, and the other peak occurs in older males and females (who are equally affected). It is associated with Psoriasis , dactylitis (swollen digits), nail pits, or a family history of psoriasis in a 1st-degree relative. Arthritis is frequently oligoarticular. Undifferentiated JIAis diagnosed when patients do not meet criteria for any one category or meet criteria for more than one. Systemic JIA(Still disease) involves fever and systemic manifestations. 1.Petty RE, Southwood TR, Manners P, et al: International League of Associations for Rheumatology classification of juvenile idiopathic arthritis: Second revision, Edmonton, 2001.J Rheumatol31(2):390–392, 2004. PMID: 14760812 