I keep running into people who think that the terms JRA and JIA are interchangeable. They’re not. Idiopathic is not a synonym for rheumatoid.
About thirty years ago, a classification system was designed to divide Juvenile Rheumatoid Arthritis into three main types. As researchers have learned more about arthritis in children, it has become apparent that the JRA categories are too broad. Kids with very different diseases are lumped together under one diagnosis, and other kids who obviously have arthritis don’t fit into one of those three little boxes.
With the autoimmune arthritic diseases, sometimes rheumatologists take a pragmatic approach and say, “It doesn’t matter exactly which type you have, because they’re all treated the same way.” That might be true, but it also might be part of the problem. Some people don’t respond to treatment. It’s a crap-shoot figuring out which med will be the magic bullet for any particular patient. Maybe if specific diseases were better identified, we’d find a pattern and know in advance which treatment is most likely to be effective.
I’m not the only one who thinks this way. In 1994, the International League of Associations for Rheumatology (ILAR) proposed new classification criteria (known as the Santiago criteria). At a meeting in 1997, those criteria were refined, resulting in the Durban criteria. In Edmonton, in 2001, precise definitions were developed, and consequently pediatric rheumatologists now classify many types of arthritis in children as Juvenile Idiopathic Arthritis (JIA).
Although kids are now diagnosed with JIA instead of JRA, it’s inaccurate to say that JIA is the same thing. To (hopefully) show the relationship between the old JRA criteria and the current JIA criteria, consider that Juvenile Idiopathic Arthritis can be:
- Psoriatic JIA
- Enthesitis-Related Arthritis
- Undifferentiated JIA
- Anything that formerly would have been called JRA:
As you can see, anyone who was diagnosed with JRA in the past should qualify for a JIA diagnosis.* There are others, though, who now receive a JIA diagnosis who would not have been given a JRA diagnosis.
JRA and JIA have a significant amount of overlap, but they are not two different terms for the same thing.
For further reading:
- Classification of Juvenile Arthritis
- Early Identification of Juvenile Idiopathic Arthritis
- Growing Pains: The ILAR Classification of Juvenile Idiopathic Arthritis
- Juvenile Idiopathic Arthritis
*Should. In reality, there are some criteria that excludes a few kids previously diagnosed, and other criteria that means some children with a definite diagnosis under the old criteria wind up “undifferentiated” under the new criteria. Read here for one example. Rheumatologists are still pushing for a better classification system.
**JIA is not all-inclusive; children can be afflicted by other types of arthritis (non-JIA). Although some consider the origin of psoriatic arthritis known (we know there’s a link to psoriasis), it is considered idiopathic because it is not due to infectious disease, inflammatory disease, or haemato-oncologic disease. Scleroderma and lupus are considered autoimmune arthritis, but do not fall under the JIA umbrella. AS is not considered JIA (but ERA is).