Table 1.
Demographics, clinical features and laboratory data of ICIAM versus IMNM patients
| ICIAM | IMNM | P value | |
|---|---|---|---|
| Number | 24 | 38 | |
| Age, years (range) | 69 (28–86) | 55 (18–87) | 0.04 |
| Female:male | 7:14 | 19:19 | 0.5 |
| Follow-up time (days) | 396 (11–1506) | 731 (74–3602) | 0.002 |
| Statin use, n (%) | 11 (46) | 22 (58) | 0.29 |
| Clinical phenotype, n (%) | |||
| 1. Oculobulbar | 10 (42) | 0 | <0.001 |
| Ocular involvement | 9 | ||
| Bulbar involvement | 6 | ||
| 2. Generalized | 14 (58) | 38 (100) | <0.001 |
| Ocular involvement | 1 | 0 | |
| Bulbar involvement | 2 | 15 | |
| Symptoms, n (%) | |||
| Myalgia | 13 (54) | 20 (53) | 0.26 |
| Dysphagia | 9 (38) | 12 (31) | 0.4 |
| Respiratory insufficiency | 10 (42) | 10 (26) | 0.23 |
| Signs, n (%) | |||
| Ophthalmoparesis | 6 (25) | 0 | 0.003 |
| Ptosis | 6 (25) | 0 | 0.003 |
| Neck flexor weakness | 8 (33) | 24 (63) | 0.002 |
| Neck extensor weakness | 2 (9) | 8 (21) | 0.19 |
| Hamstrings weaker than quadriceps | 6 (25) | 15 (40) | 0.2 |
| Myocarditis, n (%) | 8 (33) | 0 | <0.001 |
| HyperCKemia, n (%) | 15 (68)a | 37 (100)a,b | <0.001 |
| CK > 1000 IU/l (%) | 10 (45)c | 37 (100) | 0.007 |
| Peak CK, median (range) IU/l | 686 (28–7279) | 6456 (1151–29 000) | <0.001 |
| Aldolase elevation, n (%) | 7/11 (64) | 16/16 (100) | 0.009 |
| With normal CK, n (%) | 2/7 (29)d | 0 | |
| HMGCR-IgG positive, n (%) | 0/13 | 20/38 (52) | <0.001 |
| SRP-IgG positive, n (%) | 0/13 | 4/38 (10) | <0.001 |
| Other myositis-specific antibodies | 0/11 | 2/29e | 0.24 |
| Myositis associated antibodies | 3/11 | 6/29f | 0.35 |
| AChR binding antibody positive, n (%) | 3/17 (18) | 1/3 (33)g | 0.5 |
| AChR modulating antibody positive, n (%) | 2/17 (12) | 1/3 (33)g | 0.4 |
| Striational antibody positive, n (%) | 8/17 (47) | 1/19 (5)g | 0.002 |
| Paraneoplastic antibody positive, n (%) | 3/17 (18)h | 0/18 | <0.001 |
| Lymphopenia, n (%) | 18/24(75) | 7/34 (20) | <0.001 |
| Absolute lymphocyte count, median (range; ×109/l) | 0.72 (0.05–3.5) | 1.38 (0.56–3.4) | <0.001 |
| Elevated TSH, n (%) | 4/24 (19) | 12/28 (42) | 0.14 |
| AST or ALT elevation, n (%) | 15/24 (70) | 32/35 (91) | 0.003 |
AChR = acetylcholine receptor; ALT = amino alanine transferase; AST = aspartate amino transferase; CK = creatinine kinase; HMGCR = 3-hydroxy-3-methylglutaryl-coenzyme-A reductase; ICIAM = immune checkpoint inhibitor-associated myositis; IMNM = immune-mediated necrotizing myopathy; NS = not significant; SRP, signal recognition particle; TSH, thyroid stimulating hormone.
All bold values indicate P-value < or = 0.05.
CK was not available in 2/24 patients (normal <192 in females and <336 in males).
One patient with normal CK was excluded as it was measured after initiation of immunosuppressive therapy.
Oculobulbar (n = 2) and generalized (n = 8) phenotypes.
Both patients had normal AST and ALT.
One IMNM patient with strongly positive HMGCR antibodies also had weakly positive MDA-5 antibody; one double seronegative IMNM patient had weakly positive Mi-2 antibody without cutaneous or pulmonary involvement or myopathological hallmark of dermatomyositis.
Myositis associated antibodies were positive in three ICIAM (one PM/Scl-100, one SSA and one U1-RNP) and six IMNM (one SSA and five SSB) patients.
One patient with pre-existing myasthenia gravis.
One patient with N type VGCC antibodies (0.08 nmol/l; normal <0.03 nmol/l), one patient with GAD65 antibodies (0.13 nmol/l; normal < 0.02 nmol/l) and one patient with ganglionic nicotinic AChR antibodies (0.04 nmol/l; normal < 0.01).