Demographic data of all PREVENT-JIA participants that were recruited at six centres
| Characteristics | All patients recruited n=119 |
| Female, No. (%) | 81 (69) |
| Male, No. (%) | 37 (31) |
| Missing | 1 |
| Age at disease onset, median (range), years | 6.0 (<1–15.0) |
| Duration from therapy start to inactive disease, median (range), years | 1.6 (<1–11.8) |
| Age at I1, median (range), years | 10.3 (3.0–17.5) |
| Disease duration at I1, median (range), years | 3.3 (<1–15.3) |
| JIA subtype, No. (%) | |
| Oligoarthritis (extended) | 25 (21) |
| Polyarthritis, negative rheumatoid factor | 70 (59) |
| Polyarthritis, positive rheumatoid factor | 3 (3) |
| Systemic-onset juvenile idiopathic arthritis | 4 (3) |
| Enthesitis-related arthritis | 6 (5) |
| Psoriasis arthritis | 8 (7) |
| Other | 2 (2) |
| Missing | 1 |
| Final therapy, No. (%) | |
| csDMARD, no bDMARD | 91 (77) |
| bDMARD ± csDMARD | 27 (23) |
| Missing | 1 |
bDMARD, biological DMARD; csDMARDs, conventional synthetic disease-modifying anti-rheumatic drugs; JIA, juvenile idiopathic arthritis ; MTX, methotrexate.