What is juvenile idiopathic arthritis (JIA)?

Arthritis in children is now called 'juvenile idiopathic arthritis', or JIA. It is really a group of illnesses which doctors have put under one name because they share similar symptoms.

What does juvenile idiopathic arthritis mean?
Although it seems a clumsy name, juvenile idiopathic arthritis simply means arthritis with no known cause in children or young people under 16. The word 'juvenile' means under 16 years, 'idiopathic' means doctors do not yet know what causes the illness, and 'arthritis' means one or more joints – such as the knee, elbow or wrist – are inflamed (swollen, painful and/or stiff). Doctors use the term 'juvenile idiopathic arthritis' to mean arthritis which begins before a child is 16 and lasts more than 6 weeks.

What does juvenile idiopathic arthritis mean for my child?
You may not have heard of arthritis in children before. In fact, 1 in 1,000 children in the UK has JIA. Every year about 1 in 10,000 children is diagnosed with the condition. It is almost as common in children as childhood diabetes. It can begin at any age, although it most commonly shows up in younger children. It can develop in boys or girls, although most types are more common in girls. For the vast majority of these children, arthritis is not the same as in adults. Having arthritis as a child does not normally mean your child will have arthritis as an adult.

There are still many gaps in our knowledge about JIA. Doctors do not know what causes it or why it happens in some children rather than others. There is no clear evidence that it is passed down through families, although we do know that a child's genetic (inherited) make-up has some part to play. There is no clear evidence it is caused by an infection, although scientists suspect certain illnesses may act as a trigger. The latest thinking is that JIA could be caused by an interaction between some aspect of a child's genetic make-up and other factors which act as a trigger.