What is Juvenile Rheumatoid Arthritis?
According the Mayo Clinic, chronic arthritis is classified as Juvenile Rheumatoid Arthritis (JRA) when the rheumatoid patient is under the age of 16. JRA is actually a group of autoimmune diseases grouped under one umbrella. The pattern in which symptoms appear during the first six months following onset is used to determine the subtype of JRA. JRA is also referred to by the term Juvenile Idiopathic Arthritis (JIA), noted below.
Five classifications of Juvenile Rheumatoid Arthritis
- Systemic JRA: Was formerly referred to as Still’s disease. Systemic disease can affect organs, may include fever and rash with early symptoms.
- Polyarthritis: Polyarticular JRA affects five or more joints during the first six months. It is more likely to affect neck, jaw, and small joints and more likely to affect girls.
- Oligoarthritis: This is the most common, estimated to be at least half of JRA. It is also the group with the least severe symptoms of all JRA patients. It is also called pauciarticular JRA, referring to fewer than five joints being affected during the onset period. Pauciarticular JRA is more likely to affect eyes and most likely to be outgrown as the patient reaches adulthood.
- Psoriatic JRA: Similar to adult Psoriatic Arthritis (PA), this occurs with a psoriasis rash and possible nail pitting as unique symptoms.
- Enthesitis-related arthritis (ERA): ERA is more likely to affect the spine and hips. Like the adult spondarthropathy / spondylarthropathies such as Ankylosing Spondylitis, this subtype of JRA affects the entheses (insertion points of tendons, muscles, or ligaments) and is much more likely to be present in boys. Some say permanent joint damage is much less common, but there are also difficulties in measuring damage, according to Pediatric Rheumatology.
Comparing Juvenile Rheumatoid Arthritis to Rheumatoid Arthritis
In many ways, these various classifications of Juvenile Rheumatoid Arthritis seem to mirror adult versions of autoimmune arthritis diseases. The polyarticular JRA type is most similar to adult Rheumatoid Arthritis. The patient is more likely to have a positive Rheumatoid factor (Rf) and to be eventually reclassified as having adult Rheumatoid Arthritis.
How JRA is like RA:
- Extremely heterogeneous disease
- Treated with NSAIDs, DMARDs, and Biologics
- Genetic-related causes
- Possible environmental trigger
- Possibility of joint damage
How JRA is different from RA:
- Many with JRA do outgrow the disease
- JRA is much rarer than RA
- JRA may interfere with bone growth
- JRA is less likely to have positive Rheumatoid factor
Note: Differences in terminology exist with regard to JRA. “Juvenile chronic arthritis” has been the historical term in Europe. The newest term, “Juvenile idiopathic arthritis” (JIA), is now used as an umbrella term to refer to all types of Juvenile Rheumatoid Arthritis, while distinguishing between the several subtypes. Patients whose JRA is reclassified as RA upon reaching adulthood may or may not be given an additional diagnosis. It is sometimes said that such patients may have had child-onset Rheumatoid Arthritis.
Recommended reading related to today’s topic:
- Ankylosing Spondylitis post on RA Warrior
- How Does Reactive Arthritis Compare with Rheumatoid Arthritis?
- Psoriatic Arthritis and Rheumatoid Arthritis
- To learn more about JRA, see the Pediatric Rheumatology website.
- For research, I also consulted Cleveland Clinic articles on JRA.