Score points for the European League Against Rheumatism/American College of Rheumatology classification criteria for adult and juvenile idiopathic inflammatory myopathies to be used when no better explanation for the symptoms or signs exists1
| Variable | Score points | |
| No biopsy | Biopsy | |
| Age of onset of first related symptoms | ||
| 18–40 | 1.3 | 1.5 |
| ≥40 | 2.1 | 2.2 |
| Muscle weakness | ||
| Objective symmetric weakness, usually progressive, of proximal upper extremities | 0.7 | 0.7 |
| Objective symmetric weakness, usually progressive, of proximal lower extremities | 0.8 | 0.5 |
| Neck flexors are relatively weaker than neck extensors | 1.9 | 1.6 |
| In the legs, proximal muscles are relatively weaker than distal muscles | 0.9 | 1.2 |
| Skin manifestations | ||
| Heliotrope rash | 3.1 | 3.2 |
| Gottron’s papules | 2.1 | 2.7 |
| Gottron’s sign | 3.3 | 3.7 |
| Other clinical manifestations | ||
| Dysphagia or esophageal dysmotility | 0.7 | 0.6 |
| Laboratory measurements | ||
| Anti-Jo-1 (anti-histidyl-tRNA synthetase) autoantibody positivity | 3.9 | 3.8 |
| Elevated serum levels of creatine kinase (CK)* or lactate dehydrogenase (LDH)* or aspartate aminotransferase (ASAT/AST/SGOT)* or alanine aminotransferase (ALAT/ALT/SGPT)* | 1.3 | 1.4 |
| Muscle biopsy features | ||
| Endomysial infiltration of mononuclear cells surrounding, but not invading, myofibres | 1.7 | |
| Perimysial and/or perivascular infiltration of mononuclear cells | 1.2 | |
| Perifascicular atrophy | 1.9 | |
| Rimmed vacuoles | 3.1 | |
*Serum levels above upper limit of normal.