Table III.
Characteristics by dermatomyositis-specific muscle disease
| Classic DM | Amyopathic DM | Hypomyopathic DM | P value | |
|---|---|---|---|---|
| Total after exclusion | 58 | 35 | 27 | |
| Sex | ||||
| Female | 45 (78%) | 31 (89%) | 26 (96%) | .064 |
| Male | 13 (22%) | 4 (11%) | 1 (4%) | |
| Ethnicity | ||||
| Caucasian | 41 (71%) | 29 (83%) | 25 (93%) | .18 |
| African American | 11 (19%) | 5 (14%) | 1 (4%) | |
| Other | 6 (10%) | 1 (3%) | 1 (4%) | |
| Disease onset | ||||
| Adult | 51 (88%) | 34 (97%) | 24 (89%) | .32 |
| Juvenile | 7 (12%) | 1 (3%) | 3 (11%) | |
| Age at first DM symptoms, y | 42.3 (19) | 45.0 (17) | 38.0 (16) | .32 |
| Age at DM diagnosis, y | 44.6 (19) | 48.4 (16) | 43.1 (17) | .46 |
| Symptom onset to DM diagnosis, y | 2 (7) | 3.4 (7) | 5.1 (7) | .21 |
| Malignancy | ||||
| Malignancy | 9 (16%) | 3 (9%) | 2 (7%) | .57 |
| Cutaneous manifestations | ||||
| Heliotrope | 36 (62%) | 18 (51%) | 13 (48%) | .42 |
| Gottron's papules | 50 (86%) | 31 (89%) | 24 (89%) | 1.0 |
| Gottron's sign | 50 (86%) | 30 (86%) | 24 (89%) | 1.0 |
| V sign | 41 (71%) | 23 (66%) | 23 (85%) | .20 |
| Shawl sign | 40 (69%) | 20 (57%) | 23 (85%) | .056 |
| Periorbital edema | 43 (74%) | 22 (63%) | 17 (63%) | .42 |
| Linear extensor erythema | 43 (74%) | 33 (94%) | 24 (89%) | .029* |
| Calcinosis | 10 (17%) | 1 (3%) | 4 (15%) | .10 |
| Periungual erythema | 43 (74%) | 25 (71%) | 17 (63%) | .55 |
| Cuticular changes | 29 (50%) | 11 (31%) | 7 (26%) | .065 |
| Mechanic's hands | 15 (26%) | 4 (11%) | 2 (7%) | .072 |
| Facial erythema | 44 (76%) | 25 (71%) | 21 (78%) | .86 |
| Livedo reticularis | 10 (17%) | 1 (3%) | 1 (4%) | .054 |
| Hair thinning | 13 (22%) | 2 (6%) | 5 (19%) | .096 |
| ILD | ||||
| Present | 23 (40%) | 9 (26%) | 11 (44%) | .27 |
| Absent | 35 (60%) | 26 (74%) | 14 (56%) | |
| CPK† | ||||
| Average | 2407 (5361) | 91 (51) | 353 (788) | .0092* |
| Aldolase† | ||||
| Average | 19 (34) | 6 (2) | 10 (15) | .078 |
| ESR† | 48 (101) | 20 (25) | 24 (24) | .21 |
| EMG | ||||
| c/w DM | 33 (81%) | 0 (0%) | 5 (36%) | <.001* |
| Not c/w DM | 8 (20%) | 7 (100%) | 9 (64%) | |
| MRI | ||||
| c/w DM | 17 (63%) | 0 (0%) | 6 (43%) | .012* |
| Not c/w DM | 10 (37%) | 6 (100%) | 8 (57%) | |
| Muscle biopsy | ||||
| c/w DM | 33 (94%) | 0 (0%) | 1 (33%) | .0042* |
| Not c/w DM | 2 (6%) | 1 (100%) | 2 (67%) | |
| CT chest | ||||
| ILD | 14 (74%) | 6 (86%) | 2 (50%) | .35 |
| Normal | 1 (5%) | 1 (14%) | 1 (25%) | |
| Other | 4 (21%) | 0 (0%) | 1 (25%) |
CPK, Creatine phosphokinase; CT, computed tomography; c/w, consistent with; DM, dermatomyositis; EMG, electromyography; ESR, erythrocyte sedimentation rate; ILD, interstitial lung disease; MRI, magnetic resonance imaging.
*
P values reflect comparisons between classic DM and amyopathic DM.
†
Values are not normally distributed.