Demographic information, MG-related history, therapy, and outcomes in the most recent follow-up among patients with seronegative and AchR-positive MG.
| Variables | AchR (n=78) | Double seronegative (n=13) | Anti-MuSK (n=4) | P-value |
|---|---|---|---|---|
| Mean±SD or n (%) | ||||
| Current age (years) | 43.4±17.1 | 39.7±17.4 | 38.5±29.7 | 0.69 |
| Age at onset (years) | 35.3±16.3 | 35.2±16.1 | 32.5±32.9 | 0.95 |
| Disease duration (years) | 8.5±7.4 | 5.5±5.2 | 6.6±8.2 | 0.38 |
| Follow-up duration (months) | 36.1±13.4 | 27.8±15.4 | 29.5±17.5 | 0.11 |
| History of autoimmune disorder | 22 (28.2) | 3 (23.1) | 1 (25.0) | 0.92 |
| MG type | 0.23 | |||
| Ocular | 4 (5.1) | 2 (15.4) | 1 (25.0) | |
| Generalized | 74 (94.9) | 11 (84.6) | 3 (75.0) | |
| MG-QOL15R-A | 5.1±5.9 | 3.8±5.0 | 11.3±8.7 | 0.25 |
| MG-ADL-A | 1.76±2.4 | 0.9±1.4 | 3.3±2.2 | 0.13 |
| MGCS | 1.7±2.8 | 1.2±1.7 | 1.7±1.5 | 0.79 |
| MG-MMT | 2.3±5.0 | 1.4±1.8 | 0.7±1.2 | 0.87 |
| MGFA | 0.61 | |||
| CSR | 4 (5.1) | 0 | 1 (25.0) | |
| PR | 43 (55.1) | 6 (46.2) | 2 (50.0) | |
| MGFA I | 5 (6.4) | 5 (38.5) | 0 | |
| MGFA II | 24 (30.8) | 2 (15.4) | 1 (25.0) | |
| MGFA III | 2 (2.6) | 0 | 0 | |
| MG crisis | 17 (21.8) | 2 (15.4) | 2 (50.0) | 0.35 |
| MG exacerbation | 32 (41.0) | 2 (15.4) | 3 (75.0) | 0.07 |
| Refractory MG | 10 (12.8) | 0 | 2 (50.0) | 0.03* |
| Thymectomy | 58 (74.4) | 2 (15.4) | 1 (25.0) | <0.001† |
| Thymoma | 10 (12.8) | 0 | 0 | 1.00 |
| Thymic hyperplasia | 28 (35.9) | 1 (7.7) | 1 (25.0) | 1.00 |
| Therapy at last follow-up | ||||
| Prednisolone | 65 (83.3) | 9 (69.2) | 3 (75.0) | 0.47 |
| Pyridostigmine | 52 (66.7) | 7 (53.8) | 0 | 0.02‡ |
| Azathioprine | 38 (49.4) | 5 (38.5) | 2 (50.0) | 0.77 |
| Mycophenolate | 14 (17.9) | 0 | 0 | 0.17 |
| Maintenance IVIg | 15 (19.2) | 0 | 1 (25.0) | 0.21 |
| Rituximab | 9 (11.5) | 0 | 2 (50.0) | 0.03* |
| Previous IVIg | 45 (57.7) | 4 (30.8) | 2 (50.0) | 0.19 |
| Previous plasma exchange | 9 (11.5) | 0 | 1 (25.0) | 0.29 |
AchR - acetylcholine receptor antibodies, CSR - complete stable remission, IVIg - intravenous immunoglobulin, M - mean, MG - myasthenia gravis, MG-ADL-A - Arabic version of the MG-activity of daily living scale, MG-MMT - MG-manual muscle test score, MGCS - MG composite score, MGFA - MG foundation of America classification, MGFA I - ocular MG, MGFA II - mild generalized MG, MGFA III - moderate generalized MG, MG-QOL15R-A - Arabic version of the MG quality-of-life revised questionnaire, MuSK - muscle specific tyrosine kinase antibodies, PR - pharmacologic remission, SD - standard deviation. Percentages (%) are derived from the total number of patients in the respective columns. All MG-specific outcome measures were derived from the last follow-up clinic visit.
↵* p=0.008 for comparisons between patients who tested positive for MuSK antibodies and double seronegative patients.
↵† p<0.001 for comparisons between patients who tested positive for AchR antibodies and double seronegative patients.
↵‡ p=0.007 for comparisons between patients who tested positive for AchR antibodies and those who tested positive for MuSK antibodies.