There are two traditional classifications of juvenile arthritis: the European classification of juvenile chronic arthritis (JCA) and the American classification of juvenile rheumatoid arthritis (JRA). Because these classifications break down into different categories, European and American research findings and treatment recommendations are difficult to use interchangeably.¹

In an effort to improve research and treatment, the International League Against Rheumatism has devised a unifying set of international criteria, using the term "juvenile idiopathic arthritis" (JIA). The word "idiopathic" means "of unknown cause." First proposed in 1995 and later revised in 1997, this classification is gaining favor among researchers and health professionals but is not yet universally used.

The table below summarizes the three classification systems.^{2, 1}

Regardless of the classification, children who develop symptoms before reaching 16 years of age are considered to have juvenile arthritis.