Juvenile rheumatoid arthritis (JRA) - Classification and epidemiology

JRA (Now also called Juvenile idiopathic arthritis or JIA) is one of the most common chronic joint disorders in kids. It is classified as follows.

1) Pauciarticular disease: (About 50% of all JRA cases) Less than 5 joints are involved. Usually large joints, such as the shoulder, elbow, hip, and knee are affected. Pauciarticular JRA is most common in kids younger than 8 years. There is 20-30% chance of developing iridocyclitis.

2) Polyarticular disease: (30% of all JRA cases) As the name suggests this type affects more than 5 joints. Unlike the pauciarticular type small joints such as those in the hands and feet are often involved.

3) Systemic onset JRA (a.k.a Stills disease, 20% of all JRA). Children present with high fevers, skin rashes, and joint pain. Acute leukemia must be excluded as it can present identically.