The main difference between juvenile idiopathic arthritis and adult rheumatoid arthritis is that many people with JIA outgrow the illness, while adults usually have lifelong symptoms. Studies estimate that by adulthood, JIA symptoms disappear in more than half of all affected children. Additionally, unlike rheumatoid arthritis in an adult, JIA may affect bone development as well as the child's growth.

Another difference between JIA and adult rheumatoid arthritis is the percentage of people who are positive for RF (the rheumatoid factor in our genetic make-up). About 70 to 80 percent of all adults with rheumatoid arthritis are positive for RF, but fewer than half of all children with juvenile idiopathic arthritis are RF positive. Presence of RF indicates an increased chance that JIA will continue into adulthood.

Material provided by the National Institute of Arthritis and Musculoskeletal and Skin Diseases. You may visit their website at www.nih.com.

Note: Juvenile idiopathic arthritis (JIA) was previously known as Juvenile rheumatoid arthritis (JRA).