Demographics between children with and without atopic dermatitis (AD)
| Non-AD (n=1 20 014) | AD (n=1 20 014) | ||
| n (%) | n (%) | P value | |
| Age, years, mean (SD)* | 4.98 (4.83) | 4.94 (4.85) | 0.05 |
| Stratified age, years | 0.99 | ||
| ≤5 | 72 320 (60.3) | 72 320 (60.3) | |
| 6–11 | 30 016 (25.0) | 30 016 (25.0) | |
| ≥12 | 17 678 (14.7) | 17 678 (14.7) | |
| Sex | 0.99 | ||
| Girl | 54 559 (45.5) | 54 559 (45.5) | |
| Boy | 65 455 (54.5) | 65 455 (54.5) | |
| Urbanization† | 0.99 | ||
| 1 (highest) | 42 190 (35.2) | 42 190 (35.2) | |
| 2 | 35 407 (29.5) | 35 407 (29.5) | |
| 3 | 20 026 (16.7) | 20 026 (16.7) | |
| 4 (lowest) | 22 391 (18.7) | 22 391 (18.7) | |
| Follow-up time, years, mean (SD)* | 4.85 (2.31) | 4.86 (2.30) | |
| Allergic rhinitis | <0.001 | ||
| No | 105 938 (88.3) | 89 107 (74.3) | |
| Yes | 14 076 (11.7) | 30 907 (25.8) | |
| Asthma | <0.001 | ||
| No | 112 223 (93.5) | 100 781 (84.0) | |
| Yes | 7791 (6.49) | 19 233 (16.0) |
χ2 test, and *t-test comparing subjects with and without atopic dermatitis
↵†The urbanization level was categorized by the population density of the residential area into four levels, with level one as the most urbanized and level four as the least urbanized.