Juvenile Idiopathic Arthritis (JIA)
Summary
Juvenile Idiopathic Arthritis (JIA) is the most common chronic rheumatic disease of childhood, defined as arthritis persisting for ≥6 weeks in a child <16 years of age, with no identifiable cause. JIA is an umbrella term for several subtypes: oligoarticular (most common; <5 joints), polyarticular (≥5 joints), systemic (Still's disease — systemic features with daily spiking fever), enthesitis-related, psoriatic, and undifferentiated. A major complication is chronic anterior uveitis, which is often asymptomatic and requires regular slit-lamp screening to prevent blindness. Treatment is multidisciplinary and includes NSAIDs, intra-articular steroids, methotrexate, and biologics (anti-TNF, anti-IL-6).
Key Facts
- Definition: Arthritis in child <16 years, ≥6 weeks, no other cause
- Most Common Subtype: Oligoarticular (40-50%)
- Systemic JIA (Still's): Daily spiking fever, salmon rash, lymphadenopathy
- Key Complication: Chronic anterior uveitis (silent; screening essential)
- Treatment: NSAIDs, Intra-articular steroids, Methotrexate, Biologics
- Screening: Regular slit-lamp for uveitis (especially ANA+ oligoarticular)
Clinical Pearls
"Uveitis is Silent": Chronic anterior uveitis causes no symptoms initially. ANA-positive oligoarticular JIA carries highest risk — screen every 3-6 months.
"Oligo = Knees and Ankles": Oligoarticular JIA typically affects large joints, especially knees and ankles.
"Quotidian Fever = Systemic JIA": Daily high spiking fevers that return to normal (or below) are classic for systemic JIA.
"Biologics Transform Prognosis": Modern biologics (anti-TNF, anti-IL-6) have dramatically improved outcomes for JIA.
Prevalence
- 1 in 1,000 children
- Most common chronic rheumatic disease of childhood
Demographics
- Oligoarticular: F > M (4:1); Peak 2-4 years
- Polyarticular: F > M (3:1); Bimodal (2-4 and 10-14 years)
- Systemic: M = F; Any age
- Enthesitis-related: M > F; Older children/adolescents
Mechanism
- Autoimmune inflammation of synovium
- T-cell mediated in most subtypes
- Cytokine-driven (IL-6, IL-1, TNF-alpha)
Systemic JIA
- Autoinflammatory rather than autoimmune
- Innate immune dysregulation
- Risk of Macrophage Activation Syndrome (MAS) — life-threatening
Subtypes
| Subtype | Joints | Extra-Articular | Risk |
|---|---|---|---|
| Oligoarticular | <5 joints (knee, ankle) | — | Uveitis (ANA+) |
| Polyarticular RF- | ≥5 joints | — | Prolonged disease |
| Polyarticular RF+ | ≥5 joints (small + large) | Nodules | Erosive, like adult RA |
| Systemic (Still's) | Any | Fever, Rash, Lymphadenopathy, Hepatosplenomegaly | MAS |
| Enthesitis-related | Lower limb + entheses | HLA-B27 associations | Ankylosing spondylitis |
| Psoriatic | Dactylitis, Nail changes | Psoriasis | Variable |
Systemic JIA Features
Joint Examination
- Swelling, warmth
- Effusion
- Reduced ROM
- Leg length discrepancy (limb overgrowth from chronic inflammation)
Extra-Articular
- Uveitis: Slit-lamp examination (often asymptomatic)
- Rash (systemic JIA)
- Hepatosplenomegaly
First-Line
| Test | Findings |
|---|---|
| FBC | Anaemia of chronic disease; Raised WCC (systemic) |
| ESR/CRP | Raised |
| ANA | Positive in oligoarticular (uveitis risk) |
| RF | Positive in some polyarticular |
| HLA-B27 | Enthesitis-related |
Imaging
| Modality | Findings |
|---|---|
| X-ray | Soft tissue swelling; Erosions (late) |
| USS | Effusion, Synovitis |
| MRI | Synovitis, Bone marrow oedema |
Ophthalmology
- Slit-lamp examination (uveitis screening)
- Frequency based on risk (ANA, age, subtype)
Management Approach
┌──────────────────────────────────────────────────────────┐
│ JUVENILE IDIOPATHIC ARTHRITIS MANAGEMENT │
├──────────────────────────────────────────────────────────┤
│ │
│ MDT CARE: │
│ • Paediatric rheumatology │
│ • Physiotherapy │
│ • Occupational therapy │
│ • Ophthalmology (uveitis screening) │
│ • Psychology │
│ │
│ PHARMACOLOGICAL: │
│ • NSAIDs (first-line symptom control) │
│ • Intra-articular corticosteroids (especially oligo) │
│ • DMARDs: Methotrexate (mainstay), Sulfasalazine │
│ • Biologics: │
│ - Anti-TNF: Adalimumab, Etanercept │
│ - Anti-IL-6: Tocilizumab (especially systemic) │
│ - Anti-IL-1: Anakinra, Canakinumab (systemic JIA) │
│ │
│ UVEITIS MANAGEMENT: │
│ • Topical steroids │
│ • Methotrexate (steroid-sparing) │
│ • Adalimumab (refractory uveitis) │
│ │
│ SYSTEMIC JIA: │
│ • IL-1 or IL-6 inhibitors first-line │
│ • Watch for MAS │
│ │
└──────────────────────────────────────────────────────────┘
Of JIA
- Chronic anterior uveitis → Cataracts, Glaucoma, Blindness
- Joint damage and erosions
- Growth impairment (local limb overgrowth or generalised stunting)
- Contractures
- Macrophage Activation Syndrome (systemic JIA)
Of Treatment
- Methotrexate: Nausea, LFT abnormalities
- Biologics: Infection risk
- Steroids: Growth suppression, Cushingoid
With Modern Treatment
- 70-80% achieve remission or low disease activity
- Biologics have transformed prognosis
Long-Term
- Some have ongoing disease into adulthood
- Uveitis may persist or recur
Key Guidelines
- ACR/AF: Juvenile Idiopathic Arthritis Management Guidelines (2019)
- BSPAR: UK Guidelines
Key Evidence
Biologics
- RCTs support anti-TNF, anti-IL-6, anti-IL-1 for JIA
What is JIA?
Juvenile Idiopathic Arthritis (JIA) is a type of arthritis that affects children. "Idiopathic" means we don't know the exact cause. It causes the joints to become swollen, stiff, and painful.
What Are the Types?
- Oligoarticular: Affects fewer than 5 joints (like knees and ankles)
- Polyarticular: Affects 5 or more joints
- Systemic (Still's disease): Comes with high fevers and a rash
Why is Eye Screening Important?
JIA can cause inflammation in the eyes (uveitis) that has no symptoms but can lead to blindness if not treated. Regular eye checks by an ophthalmologist are essential.
How is It Treated?
- Painkillers and anti-inflammatories
- Joint injections (steroids)
- Methotrexate (to control inflammation)
- Biologic medicines (if methotrexate isn't enough)
- Physiotherapy to keep joints moving
What's the Outlook?
With modern treatments, most children with JIA live normal, active lives. Some may need long-term medication.
Primary Guidelines
- Ringold S, et al. 2019 ACR/Arthritis Foundation Guideline for the Treatment of Juvenile Idiopathic Arthritis. Arthritis Care Res. 2019;71(6):717-734. PMID: 31021516
Key Studies
- Petty RE, et al. International League of Associations for Rheumatology classification of juvenile idiopathic arthritis. J Rheumatol. 2004;31(2):390-392. PMID: 14760812