Rheumatoid Arthritis vs. Juvenile Arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by pain and inflammation in more than one joint (polyarthritis) of the hands and feet.

• It’s an autoimmune disease, in which the immune system of the body attacks healthy cells, resulting in inflammation of the membrane lining the joints (synovial membrane) and damage to joint tissue.
• RA affects other organs such as the skin, heart, lungs, and eyes, resulting in side effects.

The annual incidence of RA is approximately 3 cases per 10,000 people worldwide.

Juvenile arthritis (JA) mainly affects children and causes joint swelling and stiffness.

There are several types of JA, which include:

• Oligoarticular JA:
  • There are two types of oligoarticular JA based on whether more joints are affected after six months:
    • Persistent: Affects one to four joints in the first six months without further progression of disease after six months
    • Extended: More joints get affected after a six-month gap
• Systemic onset JA: This type of JA affects one or more joints and is often accompanied by high fever and skin rash. It is the least common type of JA, affecting 1 in 10 to 1 in 7 children. Systemic onset JA can lead to inflammation of internal organs such as the heart, liver, spleen, and lymph nodes.
• Polyarticular JA: It may affect five or more joints in the first six months of disease. A blood test performed to determine the rheumatoid factor (RF) can reveal the presence of RF.
• Psoriatic arthritis: It is a combination of psoriasis and arthritis. Psoriasis may be characterized by red, scaly skin in some children. In others, children may have arthritis and two or more of the following:
  • Inflammation of a finger or toe
  • Pits or ridges in fingernails
  • A first-degree relative with psoriasis
• Enthesitis-related JA: This type of JA is a combination of arthritis and enthesitis. Enthesitis is tissue swelling at the area, where the bone meets a tendon or ligament. The most affected sites are the hips, knees, and feet.
• Undifferentiated arthritis: This type of JA does not fit into any of the above categories and is characterized by two or more symptoms that may or may not match the symptoms of other JA.

Most adults with rheumatoid arthritis (RA) test positive for the presence of rheumatoid factor (RF), whereas some test negative.

Usually, children with juvenile arthritis (JA) outgrow their disease. However, some kids with positive RF will develop arthritis during their adulthood. Children with positive RF have the second most common type of JA—polyarticular JA. Polyarticular JA is closely related to adult RA.

A blood test to confirm the presence of RF is necessary to identify if the child has an early-onset adult RA. However, an early-onset adult RA occurs rarely in about five percent of all JA diagnoses.