Demographic and clinical characteristics of participants with baseline samples from the Nordic juvenile idiopathic arthritis (JIA) cohort (n=236)
| n | Baseline (n=236) | n | 18-year follow-up (n=199) | |
| Females | 164 (69%) | |||
| Age at onset (years) | 236 | 6.0 (2.9–10.4) | ||
| ANA positive | 208 | 82 (39.4) | ||
| HLA-B27 positive | 229 | 44 (19.0) | ||
| Age at last follow-up (years) | 199 | 23.6 (20.5–27.6) | ||
| Disease duration (years) | 199 | 17.7 (16.8–18.6) | ||
| ESR, mm/hour | 194 | 12 (6.0–24.0) | 125 | 6.0 (3.0–9.0) |
| ESR>20, mm/hour | 194 | 54 (27.8) | 125 | 9 (7.2) |
| CRP, mg/L | 196 | 0.0 (0.0–10.0) | 155 | 4.0 (1.7–5.0) |
| CRP>8, mg/L | 196 | 52 (26.5) | 155 | 15 (9.7) |
| Active joint count | 236 | 1.0 (0–3.0) | 199 | 0.0 (0.0–0.0) |
| Cumulative joints | 236 | 3.0 (1.0–7.0) | 199 | 8.0 (3.0–16.0) |
| JADAS71 | 159 | 5.0 (2.0–11.0) | 184 | 2.0 (0.0–6.4) |
| CHAQ/(baseline)/HAQ | 198 | 0.3 (0.0–0.925) | 188 | 0.0 (0.0–0.25) |
| Remission off medication | NA | 193 | 76 (39.4) | |
| Inactive disease | NA | 193 | 112 (58.0) | |
| Systemic JIA | 10 (4.2%) | 7 (3.5%) | ||
| Oligoarticular persistent | 113 (47.9%) | 45 (22.6%) | ||
| Oligoarticular extended | 8 (3.4%) | 42 (21.1%) | ||
| Polyarticular RF positive | 5 (2.1%) | 2 (1.0%) | ||
| Polyarticular RF negative | 46 (19.5%) | 28 (14.1%) | ||
| Psoriatic arthritis | 2 (0.8%) | 9 (4.5%) | ||
| Enthesitis-related arthritis | 20 (8.5%) | 22 (11.1%) | ||
| Undifferentiated | 32 (13.6%) | 44 (22.1%) |
Data are expressed as median (IQR) or number of patients (%).
ANA, antinuclear antibodies; CHAQ, Childhood Health Assessment Questionnaire; CRP, C reactive protein; ESR, erythrocyte sedimentation rate; HAQ, Health Assessment Questionnaire; HLA-B27, human leucocyte antigen B27; JADAS71, Juvenile Arthritis Disease Activity Score for 71 joints; NA, not applicable; RF, rheumatoid factor.