Population characteristics
| Variable | Total (n=121) |
| Age (years: mean and SD) | 58±14.9 |
| Gender (male: n, %) | 51 (42) |
| Diagnosis (n, %) | |
| PM | 30 (25) |
| DM | 41 (34) |
| NAM | 5 (4) |
| IBM | 1 (1) |
| ASS | 37 (31) |
| Overlap myositis | 7 (6) |
| Sjogren’s syndrome | 1 |
| Sarcoidosis | 1 |
| Systemic sclerosis | 2 |
| Morphea | 1 |
| SLE | 1 |
| Mixed connective tissue disease | 1 |
| Disease duration (months: median and IQR) | 65 (106) |
| Smoking (n, %) | 53 (44) |
| MSA (≥5 AU) (n/patients checked, %) | |
| Mi-2 | |
| SRP | 7/92 (8) |
| NXP-2 | 2/95 (2) |
| MDA-5 | 8/92 (9) |
| TIF-1γ | 5/92 (5) |
| SAE-1/2 | 2/92 (2) |
| MAA (n/patients checked, %) | |
| SSA/Ro-52 (≥ 5 AU) | 3/92 (3)34/97 (35) |
| Ro-60 (≥ 7 U/mL) | 4/25 (16) |
| U1-RNP (≥ 5 U/mL) | 5/74 (7) |
| PM/Scl (≥ 7 U/mL) | 1/82 (1) |
| Anti-ARS (≥5 AU) (n/patients checked, %) | |
| Jo-1 | 31/106 (29) |
| PL-7 | 2/95 (2) |
| PL-12 | 3/95 (3) |
| EJ | 2/92 (2) |
| HMGCR (≥5 AU) (n/patients checked, %) | 4/79 (5) |
anti-ARS, anti-aminoacyl-tRNA synthetase antibodies; ASS, antisynthetase syndrome; AU, antibody units; DM, dermatomyositis; IBM, inclusion body myositis; HMGCR, anti-HMG-CoA reductase antibodies; MAA, myositis-associated antibodies; MSA, myositis-specific antibodies; NAM, necrotising autoimmune myopathy; PM, polymyositis; SLE, systemic lupus erythematosus .