Table 1. Baseline Characteristics After Age and Sex Matching.
| Characteristic | No. (%)a | ||
|---|---|---|---|
| Full cohort (N = 464 353) | AA cases (n = 1673) | Matched controls (n = 6692) | |
| Age at AA diagnosis, mean (SD), y | NA | 46.9 (16.5) | NA |
| Sex | |||
| Female | 254 505 (54.8) | 1077 (64.4) | 4308 (64.4) |
| Male | 209 848 (45.2) | 596 (35.6) | 2384 (35.6) |
| Hypothyroidism | |||
| Yes | 32 649 (7.0) | 199 (11.9) | 535 (8.0) |
| No | 431 704 (93.0) | 1474 (88.1) | 6157 (92.0) |
| Hyperthyroidism | |||
| Yes | 6158 (1.3) | 22 (1.3) | 89 (1.3) |
| No | 458 195 (98.7) | 1651 (98.7) | 6603 (98.7) |
| Vitiligo | |||
| Yes | 1637 (0.4) | 23 (1.4) | 19 (0.3) |
| No | 462 716 (99.6) | 1650 (98.6) | 6673 (99.7) |
| Hair color | |||
| Blond | 52 696 (11.3) | 128 (7.7) | 842 (12.6) |
| Red | 21 296 (4.6) | 61 (3.6) | 297 (4.4) |
| Light brown | 190 261 (41.0) | 603 (36.0) | 2722 (40.7) |
| Dark brown | 178 071 (38.3) | 719 (43.0) | 2575 (38.5) |
| Black | 22 029 (4.7) | 162 (9.7) | 256 (3.8) |
Abbreviations: AA, alopecia areata; NA, not applicable.
a
Percentage applies to column.