Topic Overview

Previously there were 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 broke down into different categories, European and American research findings and treatment recommendations were hard to use interchangeably.

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 now used by most researchers and health professionals.

The table below summarizes the three classification systems.

Classification systems for juvenile arthritis

Organization	Classification	Length of illness before diagnosis
International League Against Rheumatism	Juvenile idiopathic arthritis (JIA) Systemic JIA Polyarticular JIA, RF-positive Polyarticular JIA, RF-negative Oligoarticular JIA Persistent (1 to 4 joints) Extended (eventually affecting 5 or more joints) Psoriatic arthritis Enthesis-related arthritis Other arthritis (also called undifferentiated or unclassified arthritis)	6 weeks
American College of Rheumatology	Juvenile rheumatoid arthritis (JRA) Systemic JRA Polyarticular JRA (5 or more joints) Oligoarticular JRA (1 to 4 joints) JRA does not include similar types of childhood arthritis (juvenile ankylosing spondylitis, juvenile psoriatic arthritis).	6 weeks
European League Against Rheumatism	Juvenile chronic arthritis (JCA) Systemic JCA Polyarticular JCA (5 or more joints, RF-negative) Juvenile rheumatoid arthritis (5 or more joints, RF-positive) Oligoarticular JCA (1 to 4 joints) Juvenile psoriatic arthritis Juvenile ankylosing spondylitis	3 months

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