When rheumatoid arthritis strikes before age 16, it's called juvenile rheumatoid arthritis. Its newer name is juvenile idiopathic arthritis (JIA). Although JIA can happen any time after infancy, the most common time it develops is between 2 and 3 years of age. In adults, RA usually strikes in middle age.
Both adult RA and JIA are autoimmune diseases. That means the immune system mistakes normal parts of the body for foreign invaders and attacks them. The attacks cause swelling and pain, called inflammation. The most common part of the body attacked in JIA is the lining inside joints, the synovium.
Types of JIA
In adults, RA usually starts with joint pain and morning stiffness. But with JIA, the symptoms depend on what type of JIA a child has. There are three main types:
Oligoarticular JIA. This is the most common type of JIA, responsible for about 60% of the cases of children with JIA. Oligoarticular JIA affects fewer than four joints, usually big joints like the knees, ankles, and elbows. This type of JIA may also attack the eyes, causing redness and pain. It is more common in girls and usually starts before age 5.
Polyarticular JIA. This type of RA affects more than four joints as well as smaller joints, like the joints in the hands and feet. About 20% of children with JIA have this type.
Systemic JIA. Systemic means it affects the whole body. Only 10% of children with JIA (also known as Still’s disease) have the systemic type, boys and girls equally. It affects small joints and can lead to swelling in internal organs. It also can cause a decrease in red blood cells and an increase in white blood cells. A youngster may get a high fever and a rash weeks or months before joint symptoms start.
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JIA can be harder to diagnose than adult RA. In adults, joint changes are easy to see, and blood tests can help make a diagnosis. But children may not complain of joint pain, and their joint swelling may not be obvious in the early stages. Blood tests also are not helpful. Doctors must look for certain symptoms to diagnose JIA:
Morning swelling or stiffness
Favoring one arm or leg over the other
Reduced activity or clumsiness
Loss of appetite and weight loss
Eye pain, redness, or visual changes
Swollen lymph nodes
The goal of treatment is to control symptoms, maintain movement, and prevent damage. A child will have the best results by working with a treatment team that includes a pediatrician, a pediatric rheumatologist, a physical therapist, a rheumatology nurse, and a social worker. It's very important to keep a child with JIA active and involved in activities like school and play.
For adults with RA, the treatment may begin with oral DMARDs, disease-modifying anti-rheumatic drugs. There are also DMARD drugs called biologics that alter how the immune system works. But in children, the first choice for treatment is a nonsteroidal anti-inflammatory drug (NSAID) like Advil or Motrin. Children may need a DMARD if an NSAID is not enough to control symptoms. Biologic DMARDs must be used with caution in children because of side effects. Some DMARDs are not approved for children at all.
Steroids, which are very strong anti-inflammatory drugs that can be taken by mouth or injected into a joint have to be used with extreme caution in children and only for short periods of time. There are serious side effects, like weight gain and increased risk for infection.
Prognosis: What Happens Over Time to Children With JIA
Over time, JIA behaves differently and responds differently to treatment than adult RA. In fact, if a child has JIA into adulthood, it is still considered JIA and not adult RA. One of the biggest differences is that, in adults, RA is a progressive disease that must be treated for a lifetime. However, children with JIA may outgrow their disease, and many do.