What is Juvenile Idiopathic Arthritis (JIA)?

JIA is a form of arthritis diagnosed in people under the age of 16 (hence Juvenile). The cause of JIA is not known (hence idiopathic). JIA causes inflammation is one or more joints leading to pain, swelling and stiffness. Types of JIA include:

  • Oligoarthritis – This is the most common type of JIA and affects one to four joints. In children under five, it is most common in girls, however the opposite is true in children over eight. Oligoarthritis is usually mild and clears up with no lasting effects.
  • Extended oligoarthritis – This begins as oligoarthritis, affecting more than four joints after six months. The condition spreads to multiple joints across the body. Extended oligoarthritis can damage the joints, so doctors usually opt to treat the condition with drugs at an early stage.
  • Polyarthritis – Polyarthritis affects five or more joints in the first six months. It can come on at any age and resembles rheumatoid arthritis, especially among females developing the condition in their teens. Polyarthritis is the second most common form of JIA after oligoarthritis.
  • Enthesitis-related JIA – Entheses are the points where tendons are attached to bones. Inflammation of these regions is known as enthesitis-related JIA. People with this form of arthritis usually have it in their legs and spine.
  • Systemic onset JIA – Systemic onset JIA is the rarest of all types of JIA. It’s part of a wider condition where symptoms also include fever tiredness and rashes.
  • Undifferentiated arthritis – this is a term used by healthcare professionals to describe forms of JIA that don’t fit in with any category or type.
PP-ENB-GBR-0665. October 2017