Baseline demographic and clinical characteristics in patients with adult-onset idiopathic inflammatory myopathies.
| Characteristics | Total, n = 197 | ADM, n = 21 | DM, n = 74 | PM, n = 43 | OM, n = 38 | CAM, n = 21 | Comparison in All Groups (DM vs PM) |
|---|---|---|---|---|---|---|---|
| Mean age at initial visit (SD) | 54 (14) | 58 (16) | 54 (13) | 53 (16) | 53 (14) | 61 (12) | NS (NS) |
| Women, % | 70 | 76 | 68 | 63 | 84 | 62 | NS (NS) |
| Raynaud’s phenomenon, % | 19 | 14 | 19 | 16 | 35 | 5 | NS (NS) |
| Arthritis, % | 42 | 43 | 41 | 35 | 63 | 24 | NS (NS) |
| Typical rash, % | 61 | 100 | 100 | 0 | 18 | 90 | Yesa (p < 0.0001) |
| Skin ulcers, % | 5 | 5 | 7 | 0 | 8 | 0 | NS (NS) |
| Dysphagia, % | 21 | 0 | 20 | 10 | 22 | 65 | Yesb (NS) |
| Manual muscle testing (IQR) | 82 (72–88) | 90 (90–90) | 80 (70–88) | 82 (72–87) | 79 (72–88) | 75 (65–82) | Yesc (NS) |
| Interstitial lung disease, % | 64 | 71 | 73 | 49 | 76 | 33 | Yesd (p = 0.0102) |
| Myocarditis, % | 17 | 10 | 14 | 28 | 27 | 0 | NS (p = 0.0842) |
| Creatine kinase (IQR) | 923 (280–2582) | 111 (71–187) | 664 (221–2014) | 1733 (822–3797) | 1366 (766–3064) | 1214 (419–3991) | Yese (p = 0.0008) |
| Antinuclear antibodies, % | 45 | 43 | 32 | 47 | 63 | 60 | Yesf (NS) |
| Anti-Jo-1 antibodies, % | 16 | 0 | 14 | 24 | 21 | 15 | NS (NS) |
| Median followup for survivors, mo (IQR) | 57 (26–114) | 44 (20–98) | 54 (24–122) | 65 (24–112) | 62 (46–109) | 60 (14–116) | NS (NS) |
| Median followup for fatalities, mo (IQR) | 7, n = 53 (2–34) | 1, n = 7 (1–30) | 3, n = 20 (1–22) | 39, n = 5 (4–111) | 46, n = 7 (5–65) | 17, n = 14 (4–26) | NS (p = 0.1104) |
↵a ADM vs PM and OM, DM vs PM and OM, PM vs OM and CAM, OM vs CAM, p < 0.05.
↵b CAM vs ADM, DM, PM, and OM, p < 0.05.
↵c ADM vs CAM, OM, DM, and PM, p < 0.05.
↵d CAM vs DM and OM, p < 0.05.
↵e ADM vs DM, PM, OM, and CAM, DM vs PM, p < 0.05.
↵f DM vs OM, p < 0.05. ADM: amyopathic dermatomyositis; DM: dermatomyositis; PM: polymyositis; OM: overlap myositis; CAM: cancer-associated myositis; IQR: interquartile range; NS: not significant.