Rare Classroom: Polyarticular Juvenile Idiopathic Arthritis

Welcome to the Rare Classroom, a new series from Patient Worthy. Rare Classroom is designed for the curious reader who wants to get informed on some of the rarest, most mysterious diseases and conditions. There are thousands of rare diseases out there, but only a very small number of them have viable treatments and regularly make the news. This series is an opportunity to learn the basics about some of the diseases that almost no one hears much about or that we otherwise haven’t been able to report on very often.

Eyes front and ears open. Class is now in session.

The rare disease that we will be learning about today is:

Polyarticular Juvenile Idiopathic Arthritis

Also called juvenile rheumatoid arthritis.

What is Polyarticular Juvenile Idiopathic Arthritis?

  • Diagnosing arthritis in children dates back to the mid-1800s.
  • To be considered Juvenile Idiopathic Arthritis, the onset of the disease occurs before a child is 16 years old. 
  • Many rheumatologists find that the greater the number of joints affected, the more severe the disease and the less likely that the symptoms will eventually go into total remission. 
  • PJIA behaves the most like adult rheumatoid arthritis, and kids who have it have a protein called rheumatoid factor (RF) or anti-cyclic citrullinated peptide (CCP antibody) in their blood. 
  • There are six JIA subtypes.  And there are nearly 300,000 children in the US with arthritis.
    • About 25 percent of children with JIA will have the polyarticular form.
    • About 100,000 children in the US have Polyarticular Juvenile Idiopathic Arthritis ​
  • Poly means manySo think of polyarticular as many joints (5 or more, according to its medical definition). Juvenile simply describes the age group affected by the disease. And while arthritis means inflammation of one or more joints, idiopathic refers to the cause of the disease: it’s unknown.
  • The first signs of arthritis, which can be subtle or obvious, include limping or a sore wrist, finger, or knee. Joints may suddenly swell and remain enlarged. Stiffness in the neck, hips, or other joints also can occur.

How Do You Get It?

  • Research indicates that it is an autoimmune disease.
    • In autoimmune diseases, white blood cells can’t tell the difference between the body’s own healthy cells and germs like bacteria and viruses.
    • The immune system, which is supposed to protect the body from these harmful invaders, instead releases chemicals that can damage healthy tissues and cause inflammation and pain.
  • There is no evidence that foods, toxins, allergies or lack of vitamins play a role in developing the disease. Current research indicates that there is a genetic predisposition to JIA.
    • More than a dozen genetic markers have been identified for JIA, and hun­dreds more are being considered.
    • However, genetic markers alone can’t determine who will get arthritis. Researchers believe that a trigger, like a virus, can start the disease process in those children with the genetic tendency.

What Are The Symptoms?

  • Kids with polyarticular JIA are at a higher risk of joint damage with erosions than in the other forms of JIA.
  • Full range of symptoms can include:
    • Joint pain​
      • Children may not understand joint pain and my act upset or irritable ​
    • Joint swelling or limping​
    • Joints that are warm to the touch​
    • Fatigue and stiffness​
    • “Silent” eye inflammation ​
      • Only visible with an eye exam​
    • Fever​
    • Rash​
    • Inability to bend or straighten joints completely​
    • Sleep problems​
    • Swollen lymph nodes​
    • Reduced appetite and/or weight loss​

How Is It Treated?

  • A number of approaches may be considered for treating this disease that may include:
    • Physical and Occupational Therapy​
    • Splinting to improve joint function​
    • Surgery in rare cases to replace joints​
    • Corticosteroid injections into the joint​
    • Regular eye exams​
    • Medications to reduce inflammation and joint damage​
      • Nonsteroidal anti-inflammatory drugs (NSAIDs)
        • A mainstay of early therapy for to ease pain and inflammation; however they do not prevent joint damage
      • Disease-modifying Antirheumatic Drugs (DMARDs) 
        • Powerful anti-inflammatory medicines that can prevent joint damage, such as cartilage and bone destruction, but can take a month or more to have an effect. ​
        • They are often used in combination with other medica­tions​
        • Methotrexate is the most commonly prescribed nonbiologic DMARD in both children and adults with arthritis​
        • Other nonbiologic DMARDs used to treat JIA include sulfasalazine, leflunomide and hydroxychloroquine.​
      • Biologic response modifiers ​
        • Biologics are a subset of DMARDs. They are used to treat a number of autoimmune diseases including JIA. ​
        • These medications help to correct a faulty response by the immune system that causes arthritis inflammation. ​
        • Biologics suppress the immune system and can make a child more likely to develop infec­tions. ​
        • Biologics that are FDA-approved for use in children include abatacept, adalimumab, canakinumab, etanercept and tocilizumab​
      • Corticosteroids
        • These are strong anti-inflammatory medicines that work quickly compared to NSAIDs. ​
        • Prednisone is one type. ​
        • The doctor may prescribe small doses of corticosteroids to help quickly con­trol inflammation while waiting for DMARDs to take effect. ​
        • Corticosteroids can be given by mouth or by injection. ​
      • The latest FDA-approved treatment for polyarticular juvenile idiopathic arthritis is tofacitinib (marketed as Xeljanz), a janus activated kinase (JAK) inhibitor. This medication was approved in 2020.

Where Can I Learn More???

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