Table 2.
Components of the 2017 EULAR/ACR classification criteria for adult and juvenile IIM
| When no better explanation for the symptoms and signs exists these classification criteria can be used | ||
|---|---|---|
| Variable | Score | |
| No muscle biopsy | With muscle biopsy | |
| Age of onset of first symptom assumed to be related to the disease ≥ 18 and < 40 years | 1.3 | 1.5 |
| Age of onset of first symptom assumed to be related to the disease ≥ 40 years | 2.1 | 2.2 |
| Muscle weakness | ||
| Objective symmetric weakness, usually progressive, of the proximal upper extremities | 0.7 | 0.7 |
| Objective symmetric weakness, usually progressive, of the 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-Jo1 autoantibody present | 3.9 | 3.8 |
| Elevated serum levels of CK or LDH* or ASAT/AST/SGOT* or ALAT/ALT/SGPT* | 1.3 | 1.4 |
| Muscle biopsy features—presence of: | ||
| 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 | |
Modified from [7]
Anti-Jo1, anti-histidyl-tRNA synthetase; CK, creatine kinase; LDH, lactate dehydrogenase; ASAT/AST/SGOT, aspartate aminotransferase; ALAT/ALT/SGPT, alanine aminotransferase