Table 1. Baseline characteristics of the patients with incident rMG and those with non-rMG.
| Variable | Patient No. (%)a | P valueb | ||
|---|---|---|---|---|
| rMG | Non-rMG | |||
| Total No. of patients | 47 | 4,251 | ||
| Female | 34 (72.3) | 2,313 (54.4) | 0.014 | |
| Age, yr | 45.5 ± 14.0 | 52.2 ± 15.4 | 0.017 | |
| Age group, yr | 0.010 | |||
| 18–29 | 5 (10.6) | 492 (11.6) | ||
| 30–39 | 16 (34.0) | 677 (15.9) | ||
| 40–49 | 12 (25.5) | 928 (21.8) | ||
| 50–59 | 5 (10.6) | 933 (21.9) | ||
| 60–69 | 8 (17.0) | 709 (16.7) | ||
| 70–79 | 1 (2.1) | 418 (9.8) | ||
| 80+ | 0 (0.0) | 94 (2.2) | ||
| Comorbidity | ||||
| Hypertension | 0 (0.0) | 18 (0.4) | > 0.999 | |
| Diabetes mellitus | 4 (8.5) | 366 (8.6) | > 0.999 | |
| Dyslipidemia | 0 (0.0) | 7 (0.2) | > 0.999 | |
| Systemic lupus erythematosus | 1 (2.1) | 16 (0.4) | 0.171 | |
| Depression | 2 (4.3) | 177 (4.2) | > 0.999 | |
| Sleep disturbance | 0 (0.0) | 145 (3.4) | 0.408 | |
| Anxiety | 3 (6.4) | 133 (3.1) | 0.185 | |
| Headache | 2 (4.3) | 570 (13.4) | 0.066 | |
| Dizziness and giddiness | 6 (12.8) | 344 (8.1) | 0.274 | |
| Osteoporosis | 0 (0.0) | 148 (3.5) | 0.410 | |
| Thyroid disease | 1 (2.1) | 284 (6.7) | 0.369 | |
| Thyrotoxicosis | 2 (4.3) | 170 (4.0) | 0.712 | |
| Myalgia and myositis | 3 (6.4) | 140 (3.3) | 0.205 | |
| Unspecified functional disorder of stomach | 0 (0.0) | 13 (0.3) | > 0.999 | |
| Malignant neoplasm of thymus | 4 (8.5) | 101 (2.4) | 0.027 | |
| Benign or uncertain neoplasm of thymus | 1 (2.1) | 60 (1.4) | 0.491 | |
| Unspecified neurotic disorder | 0 (0.0) | 21 (0.5) | > 0.999 | |
| Acute upper respiratory infections of unspecified site | 6 (12.8) | 569 (13.4) | 0.901 | |
| Acute nasopharyngitis | 4 (8.5) | 457 (10.8) | 0.622 | |
| CCI | 1.09 ± 1.61 | 0.67 ± 1.13 | 0.085 | |
| CCI group | 0.025 | |||
| < 1 | 24 (51.1) | 2,689 (63.3) | ||
| 1–2 | 16 (34.0) | 1,275 (30.0) | ||
| ≥ 3 | 7 (14.9) | 287 (6.8) | ||
| Year of cohort entry | 0.365 | |||
| 2003 | 2 (4.3) | 250 (5.9) | ||
| 2004 | 1 (2.1) | 208 (4.9) | ||
| 2005 | 6 (12.8) | 270 (6.4) | ||
| 2006 | 5 (10.6) | 250 (5.9) | ||
| 2007 | 3 (6.4) | 268 (6.3) | ||
| 2008 | 2 (4.3) | 274 (6.4) | ||
| 2009 | 3 (6.4) | 286 (6.7) | ||
| 2010 | 3 (6.4) | 286 (6.7) | ||
| 2011 | 3 (6.4) | 307 (7.2) | ||
| 2012 | 6 (12.8) | 345 (8.1) | ||
| 2013 | 5 (10.6) | 383 (9.0) | ||
| 2014 | 3 (6.4) | 350 (8.2) | ||
| 2015 | 2 (4.3) | 386 (9.1) | ||
| 2016 | 3 (6.4) | 388 (9.1) | ||
| Follow-up period, yr | ||||
| Mean ± SD | 7.1 ± 3.9 | 6.9 ± 4.0 | ||
| Median (IQR) | 6.6 (6.1) | 6.2 (6.6) | ||
Data are shown as mean ± SD or number (%).
rMG = refractory myasthenia gravis, CCI = Charlson comorbidity index, SD = standard deviation, IQR = inter quartile range.
aPercentages may not total 100 because of rounding; bThe t-test was used for continuous variables, χ2 test or Fisher's exact test (expected frequency < 5) was used for binary variables, and Cochran-Mantel-Haenszel test was used for the subgroup difference in age and CCI. P values of < 0.05 were significant.