What’s the difference between JRA and JIA?  Is it just different ways of saying the same thing?  Not exactly.  There is significant overlap, but they’re not the same.

JRA stands for Juvenile Rheumatoid Arthritis; JIA stands for Juvenile Idiopathic Arthritis. 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 learned more about arthritis in children, it became apparent that the JRA categories were too broad.  Additionally, kids who obviously had arthritis didn’t fit into one of those three little boxes.  A third problem was that many people mistakenly believed that JRA=RA in kids. 

To rectify these problems, the International League of Associations for Rheumatology (ILAR ) proposed new classification criteria in 1994, and in 1997 those criteria were refined.  Then, in 2001, precise definitions were developed.    Replacing “rheumatoid” with a more accurate term is hoped to help.  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 illustrate the relationship between the old JRA criteria and the current JIA criteria, consider:

Click to enlarge

As you can see, anyone who was diagnosed with JRA in the past should qualify for a JIA diagnosis1.  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.2

For further reading:

*Classification of Juvenile Arthritis

*Growing Pains: The ILAR Classification of Juvenile Idiopathic Arthritis

*Juvenile Idiopathic Arthritis


1  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.

2 JIA is not all-inclusive; children can be afflicted by other types of arthritis (non-idiopathic). 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.

Originally published at ∞ itis
Used with permission