Table 1.
Demographics and baseline characteristics of patients with PM versus DMa
| Characteristics | PM (n = 77) | DM (n = 83) | P value |
|---|---|---|---|
| Age at diagnosis (years) | 49.7 ± 13.0 | 47.2 ± 13.9 | 0.236 |
| Females, n (%) | 60 (77.9) | 56 (67.5) | 0.139 |
| Race, n (%) | 0.042 | ||
| White, non-Hispanic | 61 (79.2) | 52 (62.7) | |
| Black | 13 (16.9) | 15 (18.1) | |
| Hispanic | 0 (0) | 2 (2.4) | |
| Asian | 0 (0) | 1 (1.2) | |
| Other or unknown | 3 (3.9) | 13 (15.7) | |
| Median [IQR] initial CK level (IU/L)b | 3,250 [846 to 11,698] | 415 [71 to 3,000] | 0.0005 |
| Interstitial lung disease, n (%) | 21 (27.3) | 16 (19.3) | 0.231 |
| Cancer, n (%) | |||
| Ever | 13 (16.9) | 12 (14.5) | 0.673 |
| Proportion diagnosed within ± 3 years of IIM diagnosis | 5 (38.5) | 11 (91.7) | 0.01 |
aCK = creatine kinase; DM = dermatomyositis; IIM = idiopathic inflammatory myopathy; PM = polymyositis. bIncludes CK values (if available) within 3 months of IIM diagnosis. Results are expressed as means ± SD or number (%).