Juvenile Rheumatoid Arthritis (Juvenile Idiopathic Arthritis, Juvenile Chronic Arthritis)

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What is Juvenile Rheumatoid Arthritis?

Juvenile rheumatoid arthritis (JRA) refers to a group of diseases causing chronic (lasting longer than 6 weeks) joint pain and swelling in children.

Who gets Juvenile Rheumatoid Arthritis?

JRA is thought to affect between 10-20 children out of every 100 000. This seems to vary according to geography, with a higher number of cases reported in countries such as Sweden and Norway.

Predisposing Factors

The cause of JRA is unknown. There is a higher risk of JRA when a family history of the disease exists.

Progression

JRA is a long term disease characterised by joint disease that at times may be minimal and at other time severe. There are major types of JRA, which have different features.

1. Oligoarthritis:

The most common form of chronic arthritis in childhood, accounting for over half of all cases. 4 or less joints are involved during the first 6 months following onset of the arthritis. Children affected are usually aged between 1 and 4 years, with girls affected nearly twice as often as boys. Joint involvement may appear to be random. Most commonly affected are the knees, ankles, wrists and elbows.

2. Polyarthritis:

This type of JRA accounts for approximately one-third of cases of chronic childhood arthritis. 5 or more joints are involved in the first 6 months following onset of the arthritis. Once again, girls are affected twice as often as boys. Onset is most common in children between the ages of 2 and 4 years. Any joints in the body may be affected. Joint deformity and disability may occur in severe cases.

3. Systemic arthritis:

Affects both boys and girls equally, and may occur at any age during childhood. It accounts for about 10% of chronic childhood arthritis. Initial presentation is with a daily spiking fever, which returns to normal between spikes. The fever may be associated with a characteristic 'salmon' pink rash seen on the upper trunk, neck and armpits. Enlargement of the liver, spleen and lymph nodes may occur. At the beginning, joint disease may be minimal, making diagnosis difficult. Eventually joint disease may occur in both large and small joints in the body. The arthritis may be long lasting; however most children recover fully. Only a small number go on to develop severe disability.

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