- Clinical science
Juvenile idiopathic arthritis (JIA, formerly called juvenile rheumatoid arthritis) is a broad term for childhood rheumatic diseases that begin before the age of 16 and involve joint inflammation lasting more than six weeks. It is classified into various types based on the pattern of joint involvement, the presence of extra-articular manifestations (e.g., uveitis, rashes, nail changes, lymphadenopathy, hepatosplenomegaly), laboratory findings, and disease prognosis. Oligoarticular JIA, which is the most common type, presents with asymmetric involvement of up to four joints (with the knee joint most often affected). Nearly half of all cases of oligoarthritic JIA are associated with anterior uveitis, which may be diagnosed by slit-lamp examination. Laboratory tests such as ESR, rheumatoid factor (RF), antinuclear antibodies (ANA), and the HLA-B27 antigen test are used to classify and determine the prognosis of JIA. Treatment of JIA is similar to that of adult rheumatoid arthritis and involves the use of NSAIDs, intra-articular steroid injections, and disease-modifying antirheumatic drugs (DMARDs) such as methotrexate. Systemic glucocorticoid therapy should be avoided because of the risk of growth impairment.
- Prevalence: 1/1000 children
- Sex: ♀ > ♂
- Age of onset: < 16 years
Epidemiological data refers to the US, unless otherwise specified.
- Arthritic symptoms: red, swollen joints, early morning stiffness, limited or painful joint movement
- Synovial thickening
- Fever and other extra-articular manifestations (e.g., uveitis, rashes, nail changes, lymphadenopathy, hepatosplenomegaly) may be present depending on the type of JIA (see “Subtypes and variants” below).
- Certain children may present with nonspecific features such as excessive crying, lethargy, decreased scholastic performance, and/or growing pains.
|Type of JIA||Epidemiology||Definition||Pattern of joint involvement|| |
Relative frequency of each type
Most common form (accounts for 50% of all JIA cases)
|2–4 years|| |
♀ > ♂ (3:1)
| ||Mostly good|
30% of cases
|1–4 years and 6–12 years (bimodal incidence)|| |
♀ > ♂
| || || ||Variable clinical course and a high risk of functional limitation|
|Seropositive polyarticular JIA|| |
< 10% of cases
|9–12 years|| |
♀ > ♂ (10:1)
| ||Persistent disease with periodic exacerbation and a high risk of progressive joint destruction|
|Systemic JIA (Still's disease)|| |
< 10% of cases
|2–4 years|| |
♀ = ♂
| ||The clinical course is highly variable; complete remission occurs in 40–50% of cases.|
The affected joints are often stiff in the mornings or after longer periods of inactivity (e.g., sitting). Mobility improves with movement and is less impaired later in the day!
A prerequisite for the diagnosis of all forms of JIA is that arthritic symptoms begin before the age of 16 and last ≥ 6 weeks!
- Blood tests are used to classify JIA, to assess the prognosis, and to rule out other similar conditions (see “Subtypes and variants” above).
- Rheumatoid factor (RF) is absent in most cases of JIA except seropositive polyarticular JIA.
- ↑ ESR is usually seen with all forms of JIA.
- ↑ Acute phase reactants (e.g., CRP; , ferritin; ) and leukocytosis are usually associated with systemic JIA.
- ↑ ANA (antinuclear antigen) levels may be seen with oligoarticular, polyarticular, and psoriatic JIA.
- Anti-CCP antibodies indicate a poor prognosis.
- CBC: Anemia, thrombocytosis, and/or leukocytosis are seen in the case of systemic JIA.
- Imaging (e.g., X-ray, ultrasound) of the affected joint
- Regular ophthalmological screening using slit lamp examination for anterior uveitis
Anterior uveitis that occurs with JIA may be asymptomatic (especially in the case of chronic anterior uveitis). However, untreated anterior uveitis is associated with a high risk of developing glaucoma, cataracts, and optic nerve damage. Therefore, early detection via slit lamp examination and swift initiation of treatment are of paramount importance!
The differential diagnosis of JIA includes other causes of nonsuppurative arthritis in children:
The differential diagnoses listed here are not exhaustive.
Most drugs that are used to treat adult rheumatoid arthritis may be used to treat JIA as well (see “Therapy” in ). However, certain forms of therapy (e.g., systemic glucocorticoid therapy) should, as a rule, be avoided in children.
- Disease-modifying antirheumatic drugs (DMARDs)
- Biologic agents: (e.g., etanercept; , adalimumab; , anakinra; , tocilizumab) are indicated if the response to DMARDs is poor.
Systemic glucocorticoid therapy (oral, IV)
- Rarely used in children because of the risk of catabolic side effects (osteoporosis, growth impairment)
- A short course of systemic glucocorticoid therapy may be prescribed in the following situations:
- Supportive therapy
- The clinical course and prognosis are highly variable (see “Subtypes and variants” above) . However, most cases (∼ 95%) resolve by puberty.
- Factors associated with a poor prognosis
Early disease onset is associated with a greater degree of growth impairment and deformity!