What is juvenile idiopathic arthritis?

Juvenile idiopathic arthritis (JIA) is a form of arthritis in children ages 16 or younger that causes inflammation and stiffness of joints for more than six weeks.  Some children can grow out of JIA, but for many, the condition can persist into adulthood.

The disease can be classified into categories based on:

• The number of joints affected
• Which joints are involved
• The symptoms present and how long they last
• Whether specific antibodies produced by the immune system are present
• Coexisting conditions such as inflammatory bowel disease or psoriasis

These variables can help doctors determine which type of juvenile idiopathic arthritis your child has, how she may be affected by the disorder, and the best treatment options for her specific condition.

Types

Types of juvenile idiopathic arthritis include:

• Oligoarticular JIA. This form of juvenile idiopathic arthritis affects about 50 percent of children with JIA, and involves four or fewer joints. Large joints — such as the knees, ankles, or elbows — are typically affected. This category of arthritis occurs most often in the toddler years and is associated with an increased risk of eye inflammation.
• Polyarticular (rheumatoid-factor positive or negative) JIA. Nearly 30 to 40 percent of children with JIA are affected by this type of the disease, which affects five or more joints. The peak ages of onset are the toddler years and adolescent years. Polyarticular disease can affect both the large and small joints, such as those on the hands and feet.
• Psoriatic arthritis. This category of arthritis occurs in children who have a personal or family history of psoriasis. Children with psoriatic arthritis can also develop swelling of an entire finger or toe, called dactylitis.
• Enthesitis-related arthritis. This category of arthritis tends to occur more in boys than girls, and often begins in early adolescence. Children with enthesitis-related arthritis often experience tenderness where the tendons and ligaments attach to bone and are at risk for developing arthritis in the lower back and spine. Children with enthesitis-related arthritis are also at risk for eye disease.
• Systemic JIA. Systemic-onset JIA (also previously called Still's disease) is the most serious, but least common form of the juvenile idiopathic arthritis. It affects 10 to 15 percent of children with JIA. This type of arthritis is characterized by joint inflammation and stiffness, rash, and periodic fevers. Systemic JIA may cause inflammation of internal organs, including the heart, liver, spleen, and lymph nodes.

Causes

Juvenile idiopathic arthritis is an autoimmune disease, which means the body's immune system attacks its own healthy cells and tissues.

The cause of JIA is unknown, but both genetic and environmental factors may play a role. All the categories of JIA, except enthesitis-related arthritis, affect girls more than boys. JIA can reoccur in families because it is at least partly caused by genes.

Signs and symptoms

Symptoms of juvenile idiopathic arthritis vary from child to child, but the most common symptoms include:

• Swollen, stiff and painful joints, especially in the morning or after a nap (joints in the knees, hands, and feet are most commonly affected) or after sitting for a long time
• Warmth of a joint
• Eye inflammation (asymptomatic in all categories of JIA except enthesitis-related arthritis)
• Decreased use of one or more particular joints
• Fatigue
• Decreased appetite, poor weight gain, and slow growth
• High fever and rash (systemic JIA only)
• Swollen lymph nodes (systemic JIA only)

Symptoms of juvenile idiopathic arthritis may resemble other medical conditions or problems. Always consult your child's doctor for a diagnosis.

Testing and diagnosis

There is no diagnostic test to determine if a child has juvenile idiopathic arthritis. Diagnosis is usually confirmed based on the following:

• Reported symptoms. Joint inflammation must be present for at least six weeks, continuously.
• Laboratory tests. Blood tests can rule out other conditions, determine the type of JIA present, and help your doctor determine appropriate screening for eye inflammation. Tests may include:
  • ANA antibody. ANA is an antibody that is present in about 20 percent of healthy people. Children with juvenile idiopathic arthritis who have a positive ANA have an increased risk of developing asymptomatic eye inflammation (uveitis). If your child tests positive for ANA, he will need to have more frequent eye exams than if he tests negative.
  • Complete blood count. This test assesses your child for anemia, an abnormally low blood count. Anemia can be a side effect of inflammation caused by from JIA or caused by intestinal inflammation.
  • Comprehensive metabolic panel. This test assesses your child’s electrolytes, liver enzymes and albumin (protein levels).
  • C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR or sed rate) tests determine if your child has inflammation in his body. Children with JIA often have an elevated CRP and/or ESR at diagnosis or as the disease progresses.
  • Rheumatoid factor (RF) test can detect whether rheumatoid factor, an antibody, is present in the blood. While RF is commonly found in the adults with rheumatoid arthritis, it is rarely found in children with JIA.
  • HLA-B27 antigen test can help determine if your child is suspected to have enthesitis-related arthritis. The antigen is only present in about 8 percent of healthy individuals.
  • Lyme antibody test helps distinguish between JIA and lyme disease, which is prevalent in the greater Philadelphia area. Both diseases share the symptom of swollen joints.
  • Joint fluid analysis involves inserting a thin, hollow needle into the joint, removing the fluid with a syringe, and examining it. The fluid contains an increased number of white cells, but not bacteria, in children with JIA.
  • Urinalysis tests your child’s urine for protein, red blood cells, white blood cells, or casts to indicate kidney disease associated with several rheumatic diseases that also cause arthritis.
• Imaging tests, to show the extent of damage to the bones, may include the following:
  • X-ray. A diagnostic test that uses invisible electromagnetic energy beams to produce images of the joints onto film. These x-rays allow your physician to assess for damage to the joints.
  • Magnetic resonance imaging (MRI). A diagnostic test that does not involve radiation and allows your physician to assess for active/ongoing inflammation in the affected joints.
  • Ultrasound. This test can be done in the clinic by your rheumatologist to assess for inflammation of the joints and the tendon insertions.

Treatments

The goal of treatment for juvenile idiopathic arthritis is to reduce pain and stiffness, prevent deformities, and help your child maintain as normal and active a lifestyle as possible.

Specific treatment for juvenile idiopathic arthritis will be determined by your child's doctor based on:

• Your child's overall health and medical history
• Extent of the condition
• Your child's tolerance for specific medications, procedures, and therapies
• Expectation for the course of the disease
• Your opinion or preference

Treatment may include:

• Nonsteroidal anti-inflammatory drugs (NSAIDs) to reduce pain and inflammation
• Injection of steroids directly into the affect joint(s)
• Disease-modifying anti-rheumatic drugs (DMARDS) such as methotrexate.
• Biologic medications such as infliximab, adalimumab, or etanercept. These medications help improve arthritis all over the body and also help reduce inflammation in skin from psoriasis or inflammation in the gut from inflammatory bowel disease.
• Regular exercise
• Physical therapy to improve and maintain muscle and joint function

Follow-up care

Children with juvenile idiopathic arthritis should be routinely monitored by a pediatric rheumatologist into adulthood. Prompt treatment can help alleviate or lessen JIA symptoms.

Regular examinations by an ophthalmologist is also recommended for children with juvenile idiopathic arthritis because of the strong connection between JIA and eye disorders. The frequency of eye exams will depend on your child’s age and whether the ANA antibody is present.

Depending on your child’s symptoms, additional follow-up may be needed by other medical specialties.

Outlook

The long-term outlook for children with juvenile idiopathic arthritis has improved dramatically in the past few decades since the introduction of newer medications (biologics).

It was previously thought that children “outgrow” juvenile arthritis. More recent data shows that the majority of children have disease that persists into adulthood. Children with the oligoarticular form of disease (less than four 4 joints) are more likely to achieve long-term remission and discontinue all medication than children with the other types of JIA.

Early recognition of disease and appropriate therapy will help to optimize functional outcomes.