Table 1.
Characteristics of total enrolled study sample and analytical study sample
| Variables | Total study sample (n = 1565) | Analytical study sample* (n = 1345) |
|---|---|---|
| Sex, n (%) | ||
| Female | 836 (53.4) | 697 (51.8) |
| Male | 729 (46.6) | 648 (48.2) |
| Age groups, n (%) | ||
| ≤ 16 years | 386 (25.1) | 336 (25.4) |
| 17 years | 843 (54.7) | 712 (53.8) |
| ≥ 18 years | 311 (20.2) | 276 (20.8) |
| Missing, n | 25 | 21 |
| Electronic cigarette use, n (%) | ||
| Never | 957 (61.9) | 812 (60.4) |
| Former | 182 (11.8) | 164 (12.2) |
| Current (any use in past 30 days) | 408 (26.3) | 369 (27.4) |
| Missing, n | 18 | 0 |
| Cigarette smoking, n (%) | ||
| Never | 870 (56.5) | 743 (55.3) |
| Former | 278 (18.1) | 244 (18.1) |
| Current (any use in past 30 days) | 391 (25.4) | 358 (26.6) |
| Missing, n | 26 | 0 |
| Household secondhand aerosol in past 7 days, n (%) | ||
| None (0 days) | 1015 (67.9) | 882 (67.0) |
| Infrequent (1–2 days) | 144 (9.6) | 128 (9.7) |
| Frequent (≥ 3 days) | 336 (22.5) | 306 (23.3) |
| Missing, n | 70 | 29 |
| Household secondhand smoke in past 7 days, n (%) | ||
| No exposure (0 days) | 876 (58.1) | 758 (57.5) |
| Infrequent exposure (1–2 days) | 146 (9.7) | 127 (9.6) |
| Frequent exposure (≥ 3 days) | 486 (32.2) | 433 (32.9) |
| Missing, n | 57 | 27 |
| Current wheeze, n (%) | ||
| Yes | 385 (28.1) | 381 (28.3) |
| Missing, n | 195 | 0 |
| Current asthma, n (%) | ||
| Yes | 246 (16.1) | 242 (18.0) |
| Missing, n | 38 | 0 |
| Current uncontrolled asthma symptoms, n (%) | ||
| Yes | 227 (16.6) | 225 (16.7) |
| Missing, n | 195 | 0 |
* Refers to a sample of participants with complete information on status of electronic cigarettes use, cigarette smoking, current wheeze, current asthma, and current uncontrolled asthma symptoms (i.e., excluding 220 participants with incomplete information)