Demographic features of 64 patients with childhood idiopathic inflammatory myopathies. Of the 17 patients with myositis overlap syndromes, 3 had mixed connective tissue disease, 3 had systemic lupus erythematosus, and the remainder had myositis in overlap with other connective tissue diseases.
| Feature | Total, n = 64 | JDM, n = 40 | JPM, n = 7 | Myositis Overlap Syndromes, n = 17 |
|---|---|---|---|---|
| Sex F/M | 48/16 | 30/10 | 5/2 | 13/4 |
| Mean age at onset, yrs | 8.3 | 8.7 | 9.8 | 10.8 |
| Mean disease duration, yrs | 4.5 | 4 | 3.5 | 4.8 |
| Mean followup, yrs | 3 | 3 | 3 | 3.8 |
JDM: Juvenile dermatomyositis; JPM: Juvenile polymyositis.