Comparison of clinical features between patients in cluster 1 and cluster 2.
| Cluster 1, n = 37 | Cluster 2, n = 33 | P | |
|---|---|---|---|
| Age at onset, yrs, mean (SD) | 30.41 (7.83) | 52.03 (9.76) | < 0.001** |
| Age at onset, yrs | |||
| 18-30 | 20 (54) | 0 (0) | < 0.001** |
| 31-40 | 14 (38) | 3 (9) | 0.005** |
| 41-50 | 3 (8) | 11 (33) | 0.008 |
| 51-60 | 0 (0) | 13 (39) | < 0.001** |
| 61-70 | 0 (0) | 4 (12) | 0.045 |
| > 70 | 0 (0) | 2 (6) | 0.22 |
| Sex | 0.40 | ||
| Male | 16 (43) | 11 (33) | |
| Female | 21 (57) | 22 (67) | |
| Duration from onset to diagnosis, months, median (IQR) | 2.0 (1.5-5.0) | 2.0 (1.0-3.5) | 0.16 |
| Muscle weakness | 0.27 | ||
| Any muscle weakness | 37 (100) | 33 (100) | |
| Severe muscle weakness | 10 (27) | 13 (39) | |
| Myalgia | 29 (78) | 25 (76) | 0.79 |
| Rash | |||
| All rash types | 29 (78) | 30 (91) | 0.15 |
| Heliotrope rash | 23 (62) | 22 (67) | 0.70 |
| V sign | 9 (24) | 22 (67) | < 0.001** |
| Shawl sign | 4 (11) | 17 (52) | < 0.001** |
| Holster sign | 4 (11) | 4 (11) | 1.000 |
| Mechanic’s hands | 3 (8) | 7 (19) | 0.22 |
| Gottron sign and papules | 8 (22) | 12 (32) | 0.17 |
| Cutaneous ulcer | 3 (8) | 6 (16) | 0.29 |
| Subcutaneous calcification | 8 (22) | 1 (3) | 0.03* |
| Subcutaneous edema | 12 (33) | 14 (42) | 0.39 |
| Arthritis | 2 (5) | 3 (9) | 0.66 |
| Interstitial lung disease | 6 (16) | 15 (45) | 0.008** |
| Dysphagia | 23 (62) | 20 (61) | 0.89 |
| WBCs, mean (SD)a | |||
| All WBCs, × 109/L | 8.12 (3.91) | 9.23 (4.33) | 0.26 |
| Neutrophils, × 109/L | 6.24 (3.81) | 7.61 (4.06) | 0.15 |
| Lymphocytes | |||
| All lymphocytes, × 109/L | 1.23 (0.67) | 0.97 (0.36) | 0.04* |
| CD3, cells/μL | 850.65 (515.96) | 741.35 (365.80) | 0.33 |
| CD4, cells/μL | 557.29 (344.89) | 511.52 (280.31) | 0.56 |
| CD8, cells/μL | 273.85 (213.90) | 212.77 (113.26) | 0.15 |
| NK, cells/μL, median (IQR) | 31.00 (19.50-64.25) | 46.50 (28.25-80.75) | 0.08 |
| B1 (cells/μL) | 63.65 (74.71) | 46.97 (64.53) | 0.35 |
| B2 (cells/μL) | 248.85 (180.29) | 244.76 (32.65) | 0.94 |
| ALT, U/L, median (IQR) | 48.0 (25.5-92.0) | 67.0 (38.0-157.5) | 0.06 |
| AST, U/L, median (IQR) | 45.0 (22.0-107.5) | 132.0 (38.5-271.0) | 0.02* |
| CK, U/L, median (IQR) | 233.0 (95.5-1685.0) | 1462.0 (177.0-6163.0) | 0.01* |
| LDH, U/L, mean (SD) | 383.65 (238.32) | 590.73 (370.32) | 0.006** |
| Albumin, g/L, mean (SD) | 36.69 (5.29) | 33.19 (7.23) | 0.02* |
| Prealbumin, mg/L, mean (SD) | 220.10 (98.05) | 182.72 (74.67) | 0.08 |
| C3, mg/dL, mean (SD) | 75.24 (25.79) | 86.32 (17.93) | 0.04* |
| C4, mg/dL, mean (SD) | 16.94 (6.43) | 20.16 (4.95) | 0.02* |
| CRP, mg/dL, median (IQR) | 0.44 (0.19-0.94) | 0.63 (0.39-1.27) | 0.12 |
| ESR, mm/h, median (IQR) | 11.0 (7.0-21.5) | 16.0 (8.0-33.0) | 0.16 |
| Serum ferritin, ng/mL, median (IQR) | 139.2 (54.0-606.0) | 312.9 (145.4-768.5) | 0.01* |
| ANA positive | 13 (35) | 17 (52) | 0.17 |
| Cancer-associated myositis | 1 (3) | 3 (12) | 0.34b |
| Muscle biopsy | 30 (81) | 25 (76) | 0.59 |
Data are in n (%) unless otherwise indicated.
↵aAll WBC values are reported as mean (SD), except for NK, which is reported as median (IQR).
↵bThese data were deleted because patients were lost to follow-up.
↵*P < 0.05.
↵**P < 0.01. ALT: alanine aminotransferase; ANA: antinuclear antibody; AST: aspartate aminotransferase; CK: creatine kinase; CRP: C-reactive protein; ESR: erythrocyte sedimentation rate; LDH: lactate dehydrogenase ; NK: natural killer; WBC: white blood cell.