<unk>  is the most common, chronic rheumatic disease of childhood. In high-income countries, yearly incidence has been estimated at 2–20 cases per 100,000 population; prevalence in these areas is estimated at 16–150 cases per 100,000 population. However, there is also a suggestion that these numbers underestimate disease prevalence: one community-based survey of school children in Western Australia reported a prevalence of 400 per 100,000. Overall prevalence is often summarised as one per thousand children. Incidence and prevalence data vary across different population and ethnic groups, with lower overall prevalence in Afro-Caribbean and Asian populations. There are also ethnic differences in the frequency of<unk>  subtypes: for example, oligoarthritis is the most common subtype in European populations, whilst polyarticular disease predominates in many other countries including Costa Rica, India, New Zealand, and South Africa. There are differences in age of onset, gender and disease outcomes based on<unk>  subtype: these are outlined in the table above.
Juvenile idiopathic arthritis
Kawasaki disease
Systemic-onset juvenile idiopathic arthritis
Reactive arthritis
Psoriatic arthritis
Rheumatoid arthritis
Relapsing polychondritis
Inflammatory arthritis