Table 1.
Demographic data of the International Myositis Classification Criteria Project cohort
| IIM (n=976) |
Comparators (n=624) |
|
|---|---|---|
|
| ||
| Sex, n (%) | ||
| Female | 652 (66.8) | 369 (59.1) |
| Male | 324 (33.2) | 255 (40.9) |
|
| ||
| Adult onset disease*, n (%) | 727 (74.5) | 509 (81.6) |
| Childhood onset disease*, n (%) | 249 (25.5) | 115 (18.4) |
|
| ||
| Age at onset of symptom, median (IQR), years | 44.0 (14.7–57.0) | 41.0 (20.0–56.0) |
|
| ||
| Age at diagnosis, median (IQR), years | 45.5 (16.2–59.3) | 45.0 (25.8–58.0) |
|
| ||
| Disease duration from time of first symptom†, median (IQR), years | 4.0 (2.0–8.0) | 4.0 (1.0–9.0) |
|
| ||
| Disease duration from time of diagnosis‡, median (IQR), years | 3.0 (1.0–6.0) | 1.8 (0.0–4.5) |
|
| ||
| Ethnicity, n (%) | ||
| Caucasian | 611 (62.6) | 360 (57.7) |
| Asian | 177 (18.1) | 156 (25.0) |
| Hispanic | 51 (5.2) | 25 (4.0) |
| African | 40 (4.1) | 28 (4.5) |
| Native American | 18 (1.8) | 4 (0.6) |
| Pacific Island | 3 (0.3) | 1 (0.2) |
| Mixed | 37 (3.8) | 22 (3.5) |
| Unknown | 54 (5.5) | 32 (5.1) |
|
| ||
| Disease onset§, n (%) | ||
| Acute (days to 2 weeks) | 45 (4.6) | 64 (10.3) |
| Subacute (> 2 weeks to ≤ 2 months) | 237 (24.3) | 88 (14.1) |
| Insidious (> 2 months to years) | 648 (66.4) | 444 (71.2) |
| NA | 46 (4.7) | 28 (4.5) |
*
Onset of first symptoms assumed to be related to the disease
†
Time from first symptom to last clinical evaluation
‡
Time from diagnosis to last clinical evaluation
§
Onset and progression of the first symptoms of the syndrome to the full disease presentation
IIM, idiopathic inflammatory myopathies; IQR, interquartile range; NA, information not available