Table 1.
Demographic and autoantibody data for the 793 children included in this study.
| Cohort (n) | Median age at onset (IQR) | Female n (%) | Autoantibody identifiable (%) |
||
|---|---|---|---|---|---|
| Total | MSA | MAA | |||
| Juvenile myositis (379)a | 6.8 (3.9–10.1) | 267a (70) | 225 (59) | 185 (49) | 40 (11) |
| JDM (316) | 6.3 (3.7–10.0) | 218 (69) | 187 (59) | 174 (55) | 13 (4) |
| JPM (6) | 12.0 (11.4–13.5) | 4 (67) | 6 (100) | 5 (83) | 1 (17) |
| Overlap CTD or MCTD (49) | 9.0 (6.7–11.7) | 40 (83) | 31 (63) | 6 (12) | 25 (51) |
| Other IIMb (8) | 8.9 (3.1–12.8) | 7 (58) | 0 | 0 | 0 |
| JIA (318c) | 6.3 (2.8–10.4) | 203 (63) | 0 | 0 | 0 |
| JSLE (21) | 16.3 (14.4–16.7) | 17 (81) | 8 (38) | 0 | 8 (38)d |
| Muscular dystrophye (27) | 9 (7.5–14) | 2 (7.4) | 0 | 0 | 0 |
| Healthy controls (48) | 13.4 (10.9–14.8) | 25 (52) | 0 | 0 | 0 |
IQR; interquartile range MSA; myositis specific autoantibody MAA; myositis associated autoantibody JDM′ juvenile dermatomyositis JPM; juvenile polymyositis CTD; connective tissue disease MCTD; mixed connective tissue disease JIA; juvenile idiopathic arthritis JSLE; juvenile-onset systemic lupus erythematosus.
380 patients screened and one patient with anti-TIF1γ and anti-U1RNP excluded from further analysis.
2 focal myositis, 2 brothers with CANDLE syndrome, 2 viral/post-infective myositis, 1 C1q deficiency infantile lupus, 1 ‘inflammatory myopathy and panniculitis’.
16 systemic, 164 oligoarticular, 8 rheumatoid factor positive polyarthritis, 78 rheumatoid factor negative polyarthritis, 22 psoriatic arthritis, 15 enthesitis related arthritis, 7 undifferentiated, 8 missing data.
All anti-U1RNP.
20 Duchenne muscular dystrophy, 5 Becker muscular dystrophy and 2 Limb Girdle muscle dystrophy type 2D.