While most rheumatoid arthritis cases generally affect adults, it doesn’t mean young children and adolescents are immune from this disease. Juvenile idiopathic arthritis (JIA), more known as juvenile rheumatoid arthritis, is a category that focuses on other several forms of chronic arthritis in children.
JIA was first known as juvenile rheumatoid arthritis in the U.S. and juvenile chronic arthritis in Europe until the late 1990s, when the names were changed to differentiate it from rheumatoid arthritis in adults. As MedicineNet highlights, JIA is considered the “most frequent chronic rheumatologic disease” among children. There are seven categories of juvenile idiopathic arthritis, namely:1,2
- Systemic arthritis or Still’s disease
- Polyarticular juvenile idiopathic arthritis — rheumatoid factor positive
- Polyarticular juvenile idiopathic arthritis — rheumatoid factor negative
- Oligoarthritis or pauciarticular juvenile rheumatoid arthritis
- Psoriatic arthritis
- Enthesitis-related arthritis
- Undifferentiated arthritis
Most cases of JIA fall under oligoarthritis, affecting around half of young patients, while polyarthritis targets nearly 30% of children with juvenile arthritis.3
What are JIA’s common symptoms?
Just like other types of arthritis, juvenile idiopathic arthritis is an autoimmune disease that occurs when the immune system attacks healthy cells and tissues.4 As a result, a child’s joints in the hands, knees and feet are affected, and he or she usually feels constant pain, swelling, tenderness or stiffness in these areas. Other indicators of JIA may include:5,6,7
- Increased warmth and redness in the joint
- High fever and skin rashes
- Limping
- Constant clumsiness
- Swollen lymph nodes
- Rashes
- Irritability
- Blurry vision
- Eye inflammation, redness or pain
- Eye infections like uveitis8
- Fatigue
- Slowing down of overall growth
- Reduced appetite
- Poor weight gain or weight loss
- Growth problems that can result in misshapen bones or unequal bone length9
What is the difference between rheumatoid arthritis and juvenile idiopathic arthritis?
The major difference between rheumatoid arthritis and juvenile idiopathic arthritis lies in the age they affect patients. RA usually affects adults, especially the elderly,10 while JIA is diagnosed if the symptoms occur in a child less than 16 years of age for at least six weeks.11
A definitive cause for juvenile idiopathic arthritis has not been identified, as doctors haven’t discovered the main triggers of autoimmune diseases like JIA. However, ongoing research is examining the possibilities of genetic and environmental factors that may trigger the disease.12
Another reason why young people may be affected with juvenile idiopathic arthritis is because they might be having an autoinflammatory condition instead of an autoimmune condition. Out of the types of JIA known today, only systemic JIA is considered an autoinflammatory disease.13,14 Although both autoinflammatory and autoimmune diseases trigger immune cell-mediated attacks on the body,15,16 there is a difference between these two conditions.
Diseases that are considered autoimmune do not have a definite cause. While genetic and environmental factors are predominantly linked to these conditions, they are not the “root cause.” On the other hand, autoinflammatory diseases may occur because some genes underwent alterations that eventually paved the way for problems in proteins needed for certain bodily functions.17,18