Overview
Juvenile idiopathic arthritis (JIA) describes a group of chronic inflammatory arthritides occurring in children <16 years old that persist for more than 6 weeks. JIA is the most common rheumatological disorder in children.
Epidemiology
- Incidence is around 1 per 10,000 per year
- More common in girls
Types
Oligoarticular (pauciarticular) JIA
Oligoarticular (pauciarticular) JIA is the most common type of JIA and makes up 50% of cases. It is called oligoarticular (or pauciarticular) means that 4 joints or less are affected. Key features include:
- Joint swelling, stiffness, and reduced range of motion
- Joint pain may be present, but this is not typically severe
- Joints are affected asymmetrically and usually large and medium joints are affected (e.g. knees, ankles, wrists, and elbows).
- Anti-nuclear antibodies (ANA) may be positive
- A positive ANA is associated with an increased risk of uveitis
Systemic onset
Systemic onset JIA is also known as Still’s disease. It has associated extra-articular features including fever, a salmon-pink rash, and lymphadenopathy. ANA tends to be negative. A positive ANA is associated with an increased risk of uveitis
Management
Overview
Management may involve the use of NSAIDs for symptom relief, intra-articular or systemic corticosteroids for acute flares, methotrexate and similar disease-modifying antirheumatic drugs (DMARDs) under specialist guidance.
Complications
- Leg length discrepancy – due to inflammation and joint erosion
- Uveitis – risk is increased if ANA is positive
- Macrophage activation syndrome – uncontrolled immune system activation can lead to fever, rash, hepatosplenomegaly, lymphadenopathy, and bruising. Blood tests may show pancytopenia, disseminated intravascular coagulation, and elevated C-reactive protein or erythrocyte sedimentation rate (ESR).
