The course of juvenile rheumatoid arthritis (JRA) is unpredictable, especially during the first few years after a child is diagnosed. JRA, also called juvenile idiopathic arthritis (JIA) or juvenile chronic arthritis (JCA), can be mild, causing few problems. Symptoms can worsen or disappear without clear reason. Eventually the pattern of symptoms becomes more predictable. In general, children with JRA have one or a combination of symptoms including joint pain, joint swelling, and joint stiffness early in the course of the disease. Many children experience sleep disturbances, including difficulty falling asleep and frequent night awakenings.⁴ Most children have good and bad days.

Of all children with JRA, 3 to 4 out of 10 children will have serious long-term disability.⁵ While the overall long-term outlook for children with JRA is often good, symptoms of the disease can continue into adulthood. Long-term disability may range from occasional stiffness, the need for pain medication, limits on physical activity to ongoing arthritis, and the need for major surgery such as joint replacement. However, for most adults who had JRA as children, any long-term problems tend to be mild and do not affect their overall quality of life. For instance, they may not be able to play certain sports, but their activities are not otherwise limited.

A child's long-term outlook is influenced by the type of juvenile rheumatoid arthritis he or she has. While a child with pauciarticular JRA (4 or fewer joints affected) has a good long-term outlook other than eye disease risk, a child with polyarticular JRA (5 or more joints) or systemic JRA (whole-body symptoms) is likely to have more long-term problems.⁶

Pauciarticular JRA (oligoarthritis)

About 40% to 60% of all children affected by JRA have the pauciarticular form.⁵ In this form of JRA, some children have joint damage that shows on X-rays within 5 years. Children with pauciarticular JRA (oligoarthritis, meaning "few joints") have a 40% to 50% chance of continuing to have disease as an adult.⁵

• Most children with pauciarticular JRA have 4 or fewer joints affected (persistent oligoarthritis).⁶
• About 20% go on to have 5 or more joints affected over time (referred to as extended oligoarthritis, resembling polyarthritis).⁶
• Children with pauciarticular JRA are at increased risk of having vision loss caused by inflammatory eye disease.⁶ Eye disease develops in about 20% of children with pauciarticular JRA.⁷
• Some children with pauciarticular JRA have uneven leg bone growth, resulting in legs of different length and muscle wasting.⁵

Polyarticular JRA (polyarthritis)

Polyarticular JRA (polyarthritis) affects many joints-often the knee, hip, wrist, elbow, and ankle joints-and may affect the small joints in the hands and feet. This type of JRA is more severe than pauciarticular JRA because it affects more joints and tends to get worse over time. Joint damage can be seen on X-ray within 2 years in some children. About 25% to 35% of children affected by JRA have the polyarticular form. Of these children, about 50% to 70% will have active disease that continues into adulthood.⁵