Demographic, clinical features and whole-body MRI findings of the 41 patients enrolled
| Median | 1st; 3rd quartile | |
|---|---|---|
| Age at study visit (years) | 8.8 | 7.1; 12.9 |
| Disease duration (years) | 0.8 | 0.3; 3.7 |
| MMT (range 0–80) | 69 | 57; 78 |
| CMAS (range 0–52) | 36 | 28; 46 |
| CHAQ (range 0–3) | 0.9 | 0.0; 1.8 |
| Patient's assessment of overall well-being (0=very good; 10=very poor) | 4.0 | 0.9; 4.8 |
| Physician's assessment of disease activity (0=minimum; 10=maximum) | 5.5 | 3.0; 7.0 |
| Physician's assessment of overall damage (0=minimum; 10=maximum) | 0.0 | 0.0; 0.0 |
| DAS total (0–20) | 10.0 | 4.0; 14.0 |
| DAS weakness (0–8) | 5.0 | 3.0; 5.0 |
| DAS skin—vasculitis (0–9) | 5.0 | 2.5; 6.5 |
| MDI total (0–35) | 1.0 | 0.0; 2.5 |
| MDI muscular (0–3) | 0.0 | 0.0; 1.0 |
| MDI cutaneous (0–5) | 0.0 | 0.0; 1.0 |
| CPK IU/l (<150 IU/l) | 124 | 72; 484 |
| LDH IU/l (84–480 IU/l) | 607 | 428; 886 |
| AST IU/l (<40 IU/l) | 37 | 25; 68 |
| CRP mg/dl (<0.46 mg/dl) | 0.45 | 0.45; 0.45 |
| ESR mm/1st h (1–5 mm/1st h) | 14.0 | 6.0; 19.0 |
| WB STIR MRI muscle score—36 items (0–72) | 32.5 | 5.5; 53.0 |
| WB STIR MRI subcutaneous score (0–8) | 0.8 | 0.0; 2.8 |
| WB STIR MRI myofascial score (0–8) | 0.0 | 0.0; 1.5 |
AST, aspartate aminotransferase; CHAQ, Childhood Health Assessment Scale; CMAS, Childhood Myositis Assessment Scale; CPK, creatine phosphokinase; CRP, C reactive protein; DAS, Disease Activity Score; ESR, Erythrocyte Sedimentation Rate; LDH, lactate dehydrogenase; MDI, Myositis Damage Index; MMT, Manual Muscle Test; WB STIR MRI, whole-body short τ inversion recovery MRI.