Classification of juvenile arthritis
- Thomas JA Lehman, MD
Thomas JA Lehman, MD
- Section Editor — Pediatric Rheumatology
- Professor of Clinical Pediatrics
- Cornell University Medical College
In order to more accurately assess the incidence of childhood arthritis and to better understand its etiology, it is necessary to rigorously yet inclusively define the diseases which cause arthritis in children. In general, criteria for the classification of the idiopathic arthritides of childhood are intended to subdivide childhood-onset arthritides in a manner that allows better understanding of their pathogenesis and treatment [1,2]. Many nomenclature systems include further "descriptors" within each category which are expected to result in additional subclassifications over time [3,4]. The purpose of these strict and sometimes confusing subtypes is to stratify patients entered into studies into homogeneous groups. Unfortunately, the intended restriction of these criteria for use only in enrolling in standardized trials never materialized. Use as diagnostic categories has resulted in additional misunderstanding.
Several changes in the terminology of juvenile arthritis have been proposed. The older terms juvenile rheumatoid arthritis (JRA, used commonly in the United States) and juvenile chronic arthritis (JCA, preferred in Europe), were replaced by the term juvenile idiopathic arthritis (JIA) at meetings of the International League of Associations for Rheumatology (ILAR) in the late 1990s. JIA incorporates all of what was called JRA in the past, and also includes all other forms of "idiopathic" arthritis in childhood. This change, while well intentioned, has led to confusion, since many clinicians assume that JIA is the same as JRA and that the new name was put in place solely in order to distinguish arthritis in children from rheumatoid arthritis in adults. It is important for clinicians to remember that all of the children within the various systems may be diagnosed accurately as having juvenile arthritis. Beyond that, all nomenclature, including the JIA classification, has shortcomings. Systems will remain imperfect until enough is known to allow classification based upon pathophysiology and genetics rather than superficial phenotypes. Nonetheless, it is necessary for clinicians to communicate with a common frame of reference. Thus, clinicians who diagnose and treat children with arthritis should at least be familiar with the JIA nomenclature, which is broadly used in textbooks and journal articles. It has become increasingly clear that many of these forms of arthritis have a distinct etiology, pathogenesis, and natural history [5-7]. Until a better classification system is devised, it is important for clinicians to recognize that this nomenclature was not intended for broad clinical use and that consensus treatment recommendations applied to all children with JIA cannot be relied upon.
The previously used juvenile rheumatoid arthritis (JRA) classification divided childhood arthritis into three subsets based upon associated symptoms and the number of joints involved (table 1):
●Systemic JRA (formerly called Still's disease) referred to patients with rash and intermittent fever, in addition to arthritis of any number of joints. It is responsible for about 10 to 15 percent of JRA cases.
●Oligoarticular JRA includes those patients with involvement of fewer than five joints after six months of illness. It accounts for approximately 50 percent of cases of JRA. However, it is now recognized that this disease consists of several distinct subgroups with varying prognosis.
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- Petty RE, Southwood TR, Baum J, et al. Revision of the proposed classification criteria for juvenile idiopathic arthritis: Durban, 1997. J Rheumatol 1998; 25:1991.
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