Incidence of wheeze or asthma between ages 9 and 17 in relation to exposure to environmental tobacco smoke (ETS) during adolescence for non-smokers
| Incident wheeze | Incident wheeze without a cold | Incidence of diagnosed asthma | |||||
|---|---|---|---|---|---|---|---|
| % (n/N)* | Adjusted IRR(95% CI)† | % (n/N)* | Adjusted IRR(95% CI)† | % (n/N)* | Adjusted IRR(95% CI)† | ||
| n, cases; N, total of exposed; IRR, incidence risk ratio; CI, confidence interval. | |||||||
| *Population comprises subjects without missing values for the outcome, exposure, and confounding variables. | |||||||
| †All models adjusted for sex, age, and study centre (for further detail see Methods). | |||||||
| ‡Additionally adjusted for duration of ETS exposure at follow up. | |||||||
| ¶Additionally adjusted for ETS exposure at home at baseline. | |||||||
| §Additionally adjusted for atopy. | |||||||
| **Additionally adjusted for intensity of active smoking and duration of active smoking. | |||||||
| ETS exposure at home at baseline‡ | |||||||
| No | 7.8 (96/1234) | 2.8 (33/1171) | 1.2 (14/1136) | ||||
| Yes | 9.5 (57/597) | 1.22 (0.87 to 1.72) | 3.9 (22/562) | 1.39 (0.79 to 2.46) | 2.2 (12/534) | 2.00 (0.84 to 4.76) | |
| ETS exposure at follow up | |||||||
| No | 8.0 (71/888) | 3.3 (20/599) | 1.4 (12/841) | ||||
| Yes | 8.8 (84/952) | 1.04 (0.74 to 1.46)¶ | 3.7 (25/677) | 1.19 (0.68 to 2.10)§ | 1.7 (15/888) | 1.25 (0.57 to 2.73)** | |
| Duration of ETS exposure at follow up (h/day) | |||||||
| Never | 8.0 (70/877) | 3.0 (25/832) | 1.5 (12/809) | ||||
| ⩽1 | 7.0 (28/399) | 0.88 (0.58 to 1.34) | 2.6 (10/381) | 0.88 (0.43 to 1.82) | 1.4 (5/369) | 0.93 (0.33 to 2.64) | |
| 1–5 | 10.5 (48/459) | 1.31 (0.92 to 1.86) | 4.0 (17/428) | 1.35 (0.74 to 2.48) | 2.2 (9/406) | 1.53 (0.63 to 3.70) | |
| >5 | 8.1 (14/172) | 1.01 (0.58 to 1.77) | 3.7 (6/164) | 1.24 (0.52 to 2.97) | 0.6 (1/155) | 0.45 (0.05 to 3.75) | |