Juvenile idiopathic arthritis is a group of related childhood diseases that begin at or before age 16 and involve persistent or recurring inflammation of the joints similar to arthritis in adults (see Rheumatoid Arthritis (RA)).
Juvenile idiopathic arthritis (JIA) is an uncommon disease characterized by inflammation of joints (arthritis) or connective tissue. The cause is unknown. Although JIA is not considered a hereditary disorder, hereditary factors may increase a child's chance of developing it.
There are several forms of JIA. Although each form has different characteristics, they share similar features. The form is determined by results of a doctor's examination and laboratory tests. Forms include the following:
Children may have one form when they are first diagnosed but sometimes develop a different form during the course of their illness.
Oligoarticular JIA is the most common form and usually affects young girls. In this form, four or fewer ("oligo" means "few") joints are affected during the first 6 months of the disease. The knee is the most frequently affected joint.
Polyarticular JIA is the second most common form. In this form, five or more ("poly" means "many") joints are affected. This form is divided into two types: rheumatoid factor negative and rheumatoid factor positive. Children who are rheumatoid factor positive have the rheumatoid factor antibody in their blood. The rheumatoid factor-positive type typically occurs in adolescent girls and closely resembles adult rheumatoid arthritis.
Enthesitis-related arthritis involves arthritis and enthesitis (painful inflammation in areas where tendons and ligaments attach to bone). It is more common among older boys who may also develop symptoms in their spine (spondyloarthropathy—see Spondyloarthritis) such as ankylosing spondylitis (see Ankylosing Spondylitis) or reactive arthritis (see Reactive Arthritis).
Psoriatic JIA typically occurs in young girls and is associated with the skin disease psoriasis (see Psoriasis), which affects the girl or her parents or siblings. The arthritis in this type frequently affects four or fewer joints.
Undifferentiated JIA is diagnosed when children do not meet criteria for any one form or meet criteria for more than one.
Systemic JIA (Still disease) is the least common form and also causes symptoms at sites other than the joints.
JIA causes symptoms in the joints and sometimes the eyes, skin, or both.
Joint symptoms occur with any type of JIA. The joints may be stiff when children awaken. Joints often become swollen and warm. Later, joints may become painful, but the pain may be milder than expected given the amount of swelling. Pain may become worse when the joint is moved. Children may be reluctant to walk or may limp. Joint pain persists for years if untreated. However, some children do not have any pain.
Enthesitis may cause tenderness of the pelvis, hip bone, spine, kneecap, the shin just below the knee, the Achilles tendon, and the sole of the foot.
Eye inflammation can occur with any type of JIA but is most common in oligoarticular JIA and rare in polyarticular JIA and systemic JIA. Inflammation typically involves the iris of the eye (iridocyclitis). Iridocyclitis in JIA usually does not cause symptoms (there is no pain or redness) but sometimes causes blurring of vision and irregular pupils. However, untreated iridocyclitis can lead to scarring and permanent loss of vision. Rarely, children with enthesitis-related arthritis have eye redness and pain and sensitivity to light.
Skin abnormalities occur mainly in psoriatic JIA and systemic JIA. Children with psoriatic JIA may have rough, psoriasis-like patches on their skin, swollen fingers and toes, and pitted nails. Children with systemic JIA sometimes develop a short-lived rash made up of flat, pink-colored or salmon-colored patches with clear centers—mainly on the trunk and the upper part of the legs or arms. The rash appears for hours at a time (often in the evening with fever) and does not always appear in the same spot.
Systemic JIA causes fever and inflammation at sites other than the joints. Children with systemic JIA typically develop a high fever and rash that frequently appear before joint pain and swelling. The fever comes and goes, usually for at least 2 weeks. The temperature is usually highest in the afternoon or evening (often 103° F [39° C] or higher) and then returns rapidly to normal. A child with fever may feel tired and irritable. The liver, spleen, and lymph nodes may enlarge. Sometimes inflammation develops in the membranes surrounding the heart (pericarditis) or the lungs (pleuritis), causing chest pain. This inflammation may cause fluid to accumulate around the heart, lungs, or other organs.
Any type of JIA can interfere with physical growth. Joint deformities may develop if untreated. When JIA interferes with growth of the jaw, a small chin (micrognathia) can result. Long-standing (chronic) joint inflammation can eventually cause deformities of or permanent damage to the affected joint.
A doctor diagnoses JIA based on the child's symptoms and the results of a physical examination. There is no single, definitive laboratory test for JIA, but some blood tests are helpful in distinguishing one form from another. Blood is tested for rheumatoid factor and antinuclear antibodies, which are present in some people with rheumatoid arthritis and related diseases (for example, autoimmune diseases, such as systemic lupus erythematosus, polymyositis, or systemic sclerosis). However, many children with JIA do not have rheumatoid factor or antinuclear antibodies in their blood.
Children with oligoarticular JIA who have antinuclear antibodies in their blood are at a higher risk of developing iridocyclitis. Children must be examined several times a year by an ophthalmologist for iridocyclitis regardless of whether symptoms are present because iridocyclitis may not cause any symptoms even though it is already causing eye inflammation. Children who have oligoarticular JIA should have an eye examination every 3 to 4 months, children who have polyarticular JIA should have an eye examination every 6 months, and children who have systemic JIA should have an eye examination once a year.
X-rays may be taken to look for characteristic changes in the bones or joints.
With treatment, 50 to 70% of children have symptom-free periods (remissions). Children who have rheumatoid factor-positive polyarticular JIA have a less favorable prognosis. With early treatment, most children function normally.
The forms of JIA are treated similarly, and the drugs used to reduce pain and inflammation are the same as for arthritis in adults (rheumatoid arthritis—see Rheumatoid Arthritis (RA)). Typically, nonsteroidal anti-inflammatory drugs (NSAIDs—see Nonsteroidal Anti-Inflammatory Drugs) are given to reduce symptoms and are most useful for enthesitis-related arthritis. However, although NSAIDs help relieve symptoms, they do not stop the progression of joint disease.
Certain arthritis drugs called disease-modifying antirheumatic drugs (DMARDs—see Disease-modifying antirheumatic drugs (DMARDs)) can slow the progression of JIA and have dramatically improved outcomes. DMARDs include methotrexate, etanercept (which blocks tumor necrosis factor [TNF]-alpha, a protein involved in inflammation), and anakinra (which blocks interleukin-1, a protein involved in inflammation), or canakinumab (which is an antibody to interleukin-1). Side effects of methotrexate include bone marrow depression and liver toxicity, so children taking this drug require regular blood tests. Sulfasalazine, another DMARD, is given occasionally, especially to children who may have a spondyloarthropathy. Systemic JIA often responds well to therapy that blocks the effects of interleukin-1.
Doctors try to avoid using corticosteroids. However, children with severe systemic JIA sometimes require corticosteroids (such as prednisone) given by mouth. When corticosteroids are necessary, the lowest possible dose is used to decrease the chance of long-term complications such as slowed growth, osteoporosis, cataracts, and osteonecrosis (death of bone tissue). Doctors may inject corticosteroids directly into the affected joint or joints.
Iridocyclitis is treated with corticosteroid eye drops, which suppress inflammation. If this treatment is not enough, methotrexate is frequently used and, if needed, a drug that blocks the effects of tumor necrosis factor. Eye drops that widen (dilate) the pupil also help prevent permanent eye damage. Eye surgery may be needed if the eye has been damaged.
As in rheumatoid arthritis in adults, nondrug therapies are used for children. For example, physical therapy, splinting, and flexibility exercises help maintain strength and joint function.
Last full review/revision November 2013 by David D. Sherry, MD; Frank Pessler, MD, PhD