Prevalence of JIA subsets and other selected features in various countries*.
| Countryreference | Italy5 (n = 618) | Scandinavia6 (n = 315) | Canada7 (n = 1082) | Costa Rica8 (n = 122) | Turkey9 (n = 634) | Oman10 (n = 107) | South Africa11 (n = 78) | India12 (n = 235) | Taiwan13 (n = 195) |
|---|---|---|---|---|---|---|---|---|---|
| Years of patient enrollment | 2007–2009 | 1997–1998 | 1984–2002 | 1993–1995 | 2008–2009 | 2004–2013 | 2010–2011 | 1994–2005 | 1995–2010 |
| Mean/median age at onset, yrs | 2.9 | 6.8 | 6.9 | 10.8 | 4.3 | 6.8 | 8 | 12 | 9.5 |
| Female | 79.1 | 62.5 | 65.6 | 61.5 | 55.8 | 71 | 50 | 41.7 | 45 |
| Systemic arthritis | 7.4 | 4 | 14.5 | 3.6 | 14.5 | 17.8 | 7.7 | 8 | 19 |
| Oligoarthritis | 58.7 | 46 | 38.6 | 70.9 | 41.3 | 31.8 | 26.8 | 21 | 23.1 |
| RF-negative polyarthritis | 22.3 | 21a | 20.6 | 16.4a | 20.3 | 39.2 | 26.9 | 17 | 11.8 |
| RF-positive polyarthritis | 1.5 | 3.1 | 3.2 | 7.5 | 14 | 12 | 4.6 | ||
| Psoriatic arthritis | 2.4 | 3 | 11.3 | 9.1b | 2.1 | 0.9 | 1.3 | 1 | 1.5 |
| Enthesitis-related arthritis | 2.1 | 4 | 10.6 | 18.9 | 2.8 | 23 | 36 | 37.4 | |
| Undifferentiated arthritis | 4 | 22 | 1.3 | — | — | 0 | — | 5 | 2.6 |
| Uveitis | 15.6c | 8.6d | 13.1 | 3.3 | 11.6 | 0 | — | 3.8 | 6.7 |
| Positive ANA | 58.3c | 33.5e | 55.7 | 6.3 | 30.1 | 21.5 | 4.5f | 12.5g | 8.7m |
| Positive HLA-B27 | — | — | 30.6h | 26.3i | 16.7 | — | 23.1 | 48.3l | 32.3 |
↵* Data are percentages, unless otherwise indicated.
↵a RF-negative and RF-positive polyarthritis combined;
↵b includes children with probable juvenile ankylosing spondylitis, juvenile psoriatic arthritis, and arthropathies associated with inflammatory bowel disease;
↵c data from reference14;
↵d in the first 6 months of illness;
↵e tested in 197 patients;
↵f tested in 67 patients;
↵g tested in 184 patients;
↵h tested in 206 patients;
↵i tested in 110 patients;
↵l tested in 143 patients;
↵m patients with ANA titer ≥ 1:160. JIA: juvenile idiopathic arthritis; RF: rheumatoid factor; ANA: antinuclear antibody.