Table 1.
Characteristics of Study Subjects in Terms of the Level of Serum Anti–Thyroid Peroxidase Antibody
| Total (n=6685) | TPO-Ab(−) (n=6012) | TPO-Ab(+) (n=673) | p-Value | |
|---|---|---|---|---|
| Age (years) | 54.1±8.9 | 54.1±8.9 | 54.4±8.3 | 0.414 |
| Female [n (%)] | 2793 (41.8) | 2366 (39.4) | 427 (63.4) | <0.001 |
| BMI (kg/m2) | 24.2±3.2 | 24.2±3.2 | 23.9±3.1 | 0.019 |
| Smoking [n (%)] | 3258 (48.7) | 3012 (50.1) | 246 (36.6) | <0.001 |
| Serum calcium (mg/dL) | 8.9±0.3 | 8.9±0.3 | 8.9±0.3 | 0.882 |
| TSHa (mU/L) | 2.0±1.0 | 2.0±1.0 | 2.1±1.0 | 0.02 |
| fT4 (ng/dL) | 1.3±0.2 | 1.3±0.2 | 1.3±0.4 | 0.153 |
| TPO-Aba (U/mL) | 13.4±10.1 | 10.5±10.1 | 522.7±10.2 | <0.001 |
| Health checkup seasons [n (%)] | 0.069 | |||
| Spring | 1914 (29) | 1741 (29) | 200 (30) | |
| Summer | 1912 (29) | 1712 (28) | 200 (30) | |
| Autumn | 1518 (23) | 1352 (22) | 166 (25) | |
| Winter | 1314 (20) | 1207 (20) | 107 (16) | |
| Health checkup months [n (%)] | 0.248 | |||
| Mar | 649 (10) | 590 (10) | 59 (9) | |
| Apr | 688 (10) | 607 (10) | 81 (12) | |
| May | 604 (9) | 544 (9) | 60 (9) | |
| Jun | 622 (9) | 555 (9) | 67 (10) | |
| Jul | 667 (10) | 594 (10) | 73 (11) | |
| Aug | 623 (9) | 563 (9) | 60 (9) | |
| Sep | 455 (7) | 406 (7) | 49 (7) | |
| Oct | 534 (8) | 469 (8) | 65 (10) | |
| Nov | 529 (8) | 477 (8) | 52 (8) | |
| Dec | 361 (5) | 337 (6) | 24 (4) | |
| Jan | 476 (7) | 432 (7) | 44 (7) | |
| Feb | 477 (7) | 438 (7) | 39 (6) | |
a
Geometric mean.
AITD, autoimmune thyroid disease; BMI, body mass index; fT4, free thyroxine; TPO-Ab, anti–thyroid peroxidase antibody; TSH, thyrotropin.