Table 3.
Diagnostic performance of different tests in the assessment of myopathy
Investigation | n | Sensitivity (%) | Specificity (%) | PPV (%) | NPV (%) |
---|---|---|---|---|---|
CK | 627 | 54.5 | 77.8 | 55.8 | 76.9 |
Myositis antibodies | 114 | 34.3 | 95.1 | 92.6 | 44.8 |
EMG | 702 | 73.5 | 90.6 | 76.1 | 89.3 |
Muscle MRI | 150 | 70.5 | 79.0 | 82.7 | 65.3 |
Biopsy | 294 | 72.5 | 84.8 | 83.1 | 75.0 |
Genetics | 176 | 37.0 | 75.7 | 51.9 | 62.9 |
Note: we have not included MRI neuroaxis as, although this was commonly requested, the test was not looking for evidence of myopathy but rather to exclude structural pathologies