Juvenile Idiopathic Arthritis

We have discussed “Adult Problems” presenting in children previously (ex, Cholecystitis, PE, Endometriosis), but this time let’s look at a pediatric problem that has an adult sounding name – Arthritis. While arthritis certainly affects adults for a variety of reasons, it does not spare are younger patients. Yes, overt infections of the joints (Septic Arthritis) are always a concern when we are evaluating the limping child, but there is another condition that may also present as a Fever of Unknown Origin. Let’s take a minute to consider Juvenile Idiopathic Arthritis;

Juvenile Idiopathic Arthritis

  • Juvenile Idiopathic Arthritis (JIA) is a heterogenous group of disorders. [Oberle, 2014]
    • All have arthritis for at least 6 weeks in duration, without other etiology.
    • All occur before 16 years of age.
    • As an entire group, JIA is the most common rheumatologic condition of childhood.
    • Can lead severe, long-term disability.
  • Subtypes of JIA include: [Oberle, 2014]
    • Oligoarticular
      • Most common subtype¬†
      • Has four or fewer joints (typically the large ones)
    • Polyarticular (5 or more joints involved)
      • ~25% of JIA cases
      • Include wide spectrum of risk factors and disease courses.
      • May be Rheumatoid Factor (RF) positive or RF negative.
      • Tend to be more refractory to therapies.
      • Have increased risk for joint damage and worse outcomes.
    • Systemic – Onset [Yasin, 2018]
      • ~10% of JIA cases
      • Severe form affecting the entire body (skin, organs, joints).
      • May be related more to auto-inflammatory disorder than autoimmune disease (like the other subtypes).
        • More extra-articular features
        • Daily spiking fevers
        • Rash
        • Lymphadenopathy
        • Hepatosplenomegaly
        • Serositis
      • Greater risk for development of Macrophage Activation Syndrome! (see below)
    • Psoriatic arthritis
      • Joints affected and scaly rash.
      • Rash found behind the ears, on the eyelids, elbows, knees, periumbilical area, and scalp.
    • Enthesitis-related arthritis (spondyloarthritis)
      • Prominently affecting insertion and origin of the muscles, ligaments, and tendons.
      • May be seen with inflammatory bowel disease or ankylosing spondylitis.
    • Undifferentiated (may fit into no category or may fit into multiple categories)
    • Of note: the nomenclature for childhood arthritis has changed many times over the past few decades.
  • Prognosis and morbidity of JIA is variable and depends on subtype. [Oberle, 2014]
    • Overall, the 1st 6 months can be dynamic with new joints and symptoms presenting.
    • The actually subtype cannot be determined until after 6 months.
    • Poor prognostic factors for Polyarticular JIA include:
      • RF +
      • Anti-CCP antibiodies +
      • Hip arthritis
      • Cervical spine arthritis
      • Erosions / joint space narrowing
      • Early hand involvement and changes of carpal length

Juvenile Idiopathic Arthritis: Therapies

  • Main goal of therapy is pain control, improved function, and disease remission. [Oberle, 2014]
  • Therapies are based on disease subtype initially, but are often tailored for the individual patient. [Oberle, 2014]
  • Main treatment options include: [Yasin, 2018; Oberle, 2014]
    • NSAIDs
    • Glucocorticoids
    • Disease Modifying Antirheumatic Drugs (DMARDs)
      • Methotrexate (often 1st line therapy for severe polyarticular disease)
      • Leflunomide, hydroxychloroquine, penicillamine, sulfasalazine, cyclosporine, tacrolimus, and thalidomide are used as alternatives.
    • Biologics (there are ever increasing numbers of these therapies)
      • TNF inhibitors
        • TNF alpha is a pro inflammatory cytokine found to be elevated in synovial fluid of JIA patients.
        • Examples: etanercept, infliximab, adalimumab
      • IL-6 Inhibitor
        • IL-6 is another pro-inflammatory cytokine that is particularly active in systemic-onset JIA.
        • Tocilizumab is a monoclonal antibody to the IL-6 receptor.
      • Abatacept – binds to CD80/86 and blocks T-cell activation.
      • Rituximab – binds B-cell CD2- receptor and decreases B-cell numbers… used for refractory cases.

Juvenile Idiopathic Arthritis: Complications

  • In addition to the joint pain and potential injury leading to long-term pain and dysfunction, there are a number of other problems associated with JIA that may cause children to present to the ED.
  • Some are related to the underlying disease process: [Abinun, 2016]
    • Eye Pain – uveitis
    • Pulmonary inflammation and scarring can occur with Systemic Onset JIA.
    • Cardiac inflammation can also be seen with Systemic Onset JIA.
    • Macrophage Activation Syndrome: [Yasin, 2018; Abinun, 2016]
      • Seen with systemic-onset JIA (as well as other rheumatic diseases).
      • Life-threatening condition
      • Manifests with fevers, overwhelming inflammation, cytopenias, coagulopathy, liver dysfunction, CNS dysfunction, and cytokine storm.
      • Other lab abnormalities: hyperferritinemia, elevated lactate, elevated D-Dimer, elevated triglycerides, decreased ESR, decreased fibrinogen.
  • Some may be more related to the consequences of the therapies:
    • Growth inhibition – chronic steroid use
    • Osteoporosis – chronic steroid use
    • Infertility – side effect of some DMARDs
    • Infection is most important to consider in the ED – [Abinun, 2016; Salonen, 2014]
      • Related to long-term use of immunosuppressive and anti-inflammatory medications.
      • Related to indwelling central lines for other therapies!

Moral of the Morsel

  • Swollen joint and fever may not be septic arthritis. Think about systemic onset juvenile idiopathic arthritis.
  • Not just about joints. Systemic onset JIA, obviously, involves multiple organ systems, but Macrophage Activation Syndrome may also complicated things!
  • The therapies may bring their own problems. Central Lines and Immunosuppressants increases risk for invasive bacterial infections!!

References

Sean M. Fox

I enjoy taking care of patients and I finding it endlessly rewarding to help train others to do the same. I trained at the Combined Emergency Medicine and Pediatrics residency program at University of Maryland, where I had the tremendous fortune of learning from world renowned educators and clinicians. Now I have the unbelievable honor of working with an unbelievably gifted group of practitioners at Carolinas Medical Center. I strive every day to inspire my residents as much as they inspire me.

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