Figure 2. Age- and sex-specific incidence of JIA, JRA, ERA, and PsA in 2009.

Incidence is higher in boys than in girls in patients with JIA aged 5–9 and 10–14 years old (male:female 2.4∶1 and 1.8∶1, respectively), ERA aged 5–9 and 10–15 years old (6.4∶1 and 3.5∶1, respectively), and PsA aged 10–15 years old (1.8∶1). Incidence is higher in females in JIA patients aged 0–4 years old (0.7∶1), JRA aged 0–4 and 10–15 years old (0.7∶1 and 0.9∶1, respectively), and PsA aged 0–9 years old (0.9∶1).