Juvenile Idiopathic Arthritis (JIA)
JIA is an arthritis of unknown cause, beginning before age 16 years, and lasting for at least 6 weeks. It affects 1 in 1000 children. The subgroups are:
- Systemic JIA (10% to 15% of all JIA)
- Oligoarthritis (30% to 60%)
- Polyarthritis, RF positive (5% to 10%)
- Polyarthritis, RF negative (10% to 30%)
- Psoriatic arthritis (2% to 15%)
- Enthesitis-related arthritis (ERA)/juvenile spondyloarthropathy (JAS) (20%)
- Undifferentiated arthritis
Juvenile idiopathic arthritis (JIA) consists of several subgroups with different clinical characteristics, pathogenesis, and responses to therapy.
- Juvenile idiopathic arthritis (JIA) consists of several subgroups with different clinical characteristics, pathogenesis, and responses to therapy.
- Systemic JIA symptoms include quotidian fever, rash, and arthritis, which responds best to interleukin (IL)-1 and IL-6 inhibition.
- Oligoarticular JIA is characterized by young age of onset, female predominance, positive antinuclear antibody (ANA), and chronic anterior uveitis.
- Polyarticular JIA with a positive rheumatoid factor (RF) resembles adult seropositive rheumatoid arthritis (RA).
- ANA positivity, female sex, and age less than 6 years old increase the risk of chronic uveitis regardless of the JIA subgroup.
- Enthesitis-related arthritis (ERA) is characterized by lower extremity enthesitis, male sex, human leukocyte antigen-B27 (HLA-B27), acute anterior uveitis, and sometimes the later development of sacroiliitis.