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]
- 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
- 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]
- 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.
- TNF inhibitors
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!!
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