Polyarticular arthritis

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Polyarticular arthritis is the second most common type of JIA in young people. Polyarticular arthritis affects five or more joints within the first six months of symptoms. Learn more about the two different types of polyarticular arthritis.

Key points

  • Polyarticular arthritis is the second most common type of JIA.
  • It affects five or more joints with the first six months of having JIA.
  • There are two types of polyarticular arthritis: polyarticular-RF positive arthritis and polyarticular-RF negative arthritis.
  • This type of JIA is more likely to last into adulthood.

Polyarticular (pronounced: pah-lee-ar-tik-yoo-lur) arthritis affects five or more joints within the first six months of having JIA. It is the second most common type of JIA in children and teenagers. There are two types of polyarticular arthritis: The first type has a positive rheumatoid factor (RF) result on a blood test, and the second type has a negative RF result. RF is an antibody that is present in the blood in certain types of JIA.

Polyarticular RF positive arthritis Identification of finger, hip, knee, ankle and toe joint and illustration of rheumatoid nodules on arm
Polyarticular RF positive arthritis is more common in young people over 10 years of age. It is characterized by symmetric involvement of more joints, rheumatoid nodules (bumps under the skin), anemia, and fatigue.

Quick facts about polyarticular — RF positive arthritis

Here are some facts about RF positive polyarticular JIA:

  • It affects 5% to 8% of young people with JIA.
  • It can occur at any age, but is more common in young people over 10 years of age.
  • It is more common in girls than boys.
  • It affects both the small joints of the hands and feet, and large joints like the knees, hips and ankles.
  • It affects joints on both sides of the body.
  • It is similar to one common adult type of JIA called rheumatoid arthritis.
  • There is a low risk of eye disease.
  • More severe inflammation may occur with this type of JIA.

With this type of JIA, your child may also have other symptoms:

  • Rheumatoid nodules, which are hard bumps under the skin.
  • Anemia, which is a low red blood cell count or reduced hemoglobin level in your blood.
  • Significant fatigue, which means you feel tired all day long.
  • A poor appetite, with some weight loss.
  • A low fever, which is less than 38.5 degrees Celsius (101.5 degrees Fahrenheit).
  • A general feeling of being unwell

These symptoms occur when the disease is active and untreated. The symptoms will improve with proper treatment.

Polyarticular RF negative arthritis Identification of wrist, knee and ankle joints in a girl
Polyarticular RF negative arthritis can occur at any age, more often in females than males. It usually starts in many joints at the same time, often symmetrically.

Quick facts about RF negative polyarticular arthritis

Here are some facts about this type of JIA:

  • It occurs in about 20% of young people who have JIA.
  • It can occur at any age.
  • It is more common in girls than boys.
  • It usually starts in many joints at the same time.
  • In some young people, it will start in only one or two joints and then spread to other joints during the first six months.

Some young people only have polyarticular JIA for a limited period of time while others may have it for many years. This type of JIA is more likely to last into adulthood. In general, most young people with RF-negative polyarticular arthritis will require treatment with disease modifying anti-rheumatic drugs (DMARDs) to control the joint inflammation. If active disease is not well controlled, young people with this type of JIA can develop joint damage, disability or have problems with their growth.


Last updated: January 31st 2017