Table 1.
Baseline characteristics of the study population
| Baseline characteristics | Overall (n = 572) | OMG-M group (n = 428) | OMG-G group (n = 144) | p value |
|---|---|---|---|---|
| Sex, n (%) | 0.27 | |||
| Male | 303/572 (53.0) | 233/428 (54.4) | 70/144 (48.6) | |
| Female | 269/572 (47.0) | 195/428 (45.6) | 74/144 (51.4) | |
| Onset age, years, mean ± SD | (45.5 ± 19.8) | (42.8 ± 20.6) | (53.5 ± 14.8) | < 0.001 |
| Onset age, years, n (%) | < 0.001a | |||
| < 18 | 62/572 (10.8) | 59/428 (13.8) | 3/144 (2.1) | |
| 18–49 | 236/572 (41.3) | 183/428 (42.8) | 53/144 (36.8) | |
| ≥ 50 | 274/572 (47.9) | 186/428 (43.5) | 88/144 (61.1) | |
| Symptoms at onset, n (%) | 0.03 | |||
| Ptosis | 358/572 (62.6) | 279/428 (65.2) | 79/144 (54.9) | |
| Diplopia/diplopia and ptosis | 214/572 (37.4) | 149/428 (34.8) | 65/144 (45.1) | |
| Comorbid autoimmune diseases, n (%)b | 0.78 | |||
| No | 555/572 (97.0) | 416/428 (97.2) | 139/144 (96.5) | |
| Yes | 17/572 (3.0) | 12/428 (2.8) | 5/144 (3.5) | |
| RNS findings, n (%) | < 0.001 | |||
| Missing | 71/572 (12.4) | 45/428 (10.5) | 26/144 (18.1) | |
| Normal | 252/501 (50.3) | 222/383 (58.0) | 30/118 (25.4) | |
| Abnormal | 249/501 (49.7) | 161/383 (42.0) | 88/118 (74.6) | |
| AChR-Ab, n (%) | < 0.001a | |||
| Missing | 42/572 (7.3) | 29/428 (6.8) | 13/144 (9.0) | |
| Seronegative | 135/530 (25.5) | 126/399 (31.6) | 9/131 (6.9) | |
| Seropositive | 395/530 (74.5) | 273/399 (68.4) | 122/131 (93.1) | |
| Neostigmine test, n (%) | 0.27a | |||
| Missing | 49/572(8.6) | 33/428(7.7) | 16/144(11.1) | |
| Negative | 18/523 (3.4) | 16/395 (4.1) | 2/128 (4.7) | |
| Positive | 505/523 (96.6) | 379/395 (95.9) | 126/128 (98.4) | |
| Thymic status, n (%) | 0.002 | |||
| Missing | 1/572 (0.2) | 1/428 (0.2) | 0 | |
| Non-thymoma | 478/571 (83.7) | 370/427 (86.7) | 108 (75.0) | |
| Thymoma | 93/571 (16.3) | 57/427 (13.3) | 36 (25.0) | |
| Follow-up period duration, months, median (IQR) | 14.5 (7.0, 47.3) | 24.0 (8.0, 57.0) | 12.0 (6.0, 24.0) | < 0.001c |
AChR-Ab Acetylcholine receptor antibody, IQR interquartile range, OMG ocular myasthenia gravis, OMG-G OMG generalized, OMG-M OMG maintenance, RNS repetitive nerve stimulation, SD standard deviation
aFisher exact test
bComorbid autoimmune diseases included systemic lupus erythematosus, multiple sclerosis, rheumatoid arthritis, Hashimoto's thyroiditis, and optic neuromyelitis spectrum disease
cMann–Whitney U test