Characteristics at disease onset: subgroups, sex distribution, onset age, laboratory signs of inflammation assessed as erythrocyte sedimentation rate (ESR), presence of rheumatoid factor (RF; titers > 1/25 are positive), and antinuclear antibody (ANA; titers > 1/20 are positive) at disease onset in 86 incidence cases of juvenile chronic arthritis followed for 17 years. Values are medians and ranges if not indicated otherwise.
| Onset Subgroup | N (%) | Girls/Boys (% girls) | Onset Age, yrs | ESR, mm/h | RF +/− | ANA +/− |
|---|---|---|---|---|---|---|
| Systemic | 6 (7) | 2/4 (33) | 7.3 (1.5–15.8) | 72 (43–124) n = 6 | 0/5 | 0/5 |
| Polyarticular | 19 (22) | 14/5 (74) | 6.0 (0.6–14.7) | 25 (3–19), n = 13 | 3/12 | 6/12 |
| Pauciarticular | 33 (38) | 27/6 (82) | 8.6 (1.4–14.9) | 30 (3–76), n = 23 | 0/25 | 13/19 |
| Monoarticular | 22 (26) | 16/6 (73) | 5.8 (1.0–12.7) | 22 (0–50), n = 19 | 1/20 | 11/11 |
| JAS | 4 (5) | 1/3 (25) | 13.8 (12.2–14.9) | 22 (12–33), n = 3 | 0/2 | 0/4 |
| JPA | 2 (2) | 1/1 (50) | 12.0 (10.2–13.8) | 44 (3–84), n = 2 | 0 | 0 |
| Total | 86 (100) | 61/25 (71) | 8.3 (0.6–15.8) | 28 (0–124), n = 66 | 4/64 | 30/51 |
JAS: juvenile ankylosing spondylitis; JPA: juvenile psoriatic arthritis.