Characteristics of JIA subtypes across cohorts, including rate (%) of each subtype among cases of each cohort. Cases with no known subtype classification were excluded (n=29 from CLARITY and n=25 from the UK)
| UK (2324 cases) | CHOP (559 cases) | CLARITY (333 cases) | |||||||
| Rate (%) | Males | Females | Rate (%) | Males | Females | Rate (%) | Males | Females | |
| Enthesitis-related | 7.4 | 136 | 37 | 11.8 | 40 | 26 | 4.4 | 13 | 3 |
| Oligoarthritis | 41.1 | 299 | 657 | 36.3 | 39 | 164 | 43.9 | 42 | 117 |
| RF-negative | 23.8 | 144 | 408 | 24.2 | 34 | 101 | 20.7 | 23 | 52 |
| RF-positive | 5.5 | 13 | 115 | 5.2 | 1 | 28 | 3.0 | 1 | 10 |
| Psoriatic | 5.9 | 50 | 86 | 7.2 | 11 | 29 | 5.0 | 12 | 6 |
| Undifferentiated | 2.1 | 21 | 28 | 4.7 | 8 | 18 | 7.5 | 13 | 14 |
| Systemic | 13.2 | 142 | 164 | 10.6 | 24 | 36 | 7.5 | 12 | 15 |
CHOP, Children’s Hospital of Philadelphia; CLARITY, ChiLdhood Arthritis Risk factor Identification sTudY; JIA, juvenile idiopathic arthritis; RF-negative, rheumatoid-factor-negative polyarthritis; RF-positive, rheumatoid-factor-positive polyarthritis.