Incidence (%) of wheeze or asthma between ages 9 and 17 in relation to active smoking during adolescence by atopy at baseline
| 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, study centre, and duration of exposure to environmental tobacco smoke (ETS) at follow up (for further detail see Methods). | ||||||
| Atopic subjects | ||||||
| Active smoking during adolescence | ||||||
| No | 13.8 (71/515) | 6.3 (30/474) | 3.4 (15/442) | |||
| Yes | 25.8 (65/252) | 1.63 (1.20 to 2.22) | 18.3 (42/229) | 2.07 (1.35 to 3.18) | 9.7 (19/196) | 2.16 (1.15 to 4.06) |
| Duration of active smoking (years) | ||||||
| Never | 13.8 (71/515) | 6.3 (30/474) | 3.4 (15/442) | |||
| ⩽2 | 18.1 (19/105) | 1.18 (0.74 to 1.87) | 12.2 (12/98) | 1.44 (0.79 to 2.64) | 3.5 (3/85) | 0.84 (0.26 to 2.69) |
| 2–4 | 26.7 (27/101) | 1.59 (1.08 to 2.34) | 17.8 (16/90) | 1.86 (1.07 to 3.23) | 13.4 (11/82) | 2.90 (1.35 to 6.21) |
| >4 | 40.5 (15/37) | 2.51 (1.58 to 3.99) | 35.3 (12/34) | 3.87 (2.16 to 6.91) | 16.7 (4/24) | 3.71 (1.39 to 9.94) |
| Intensity of active smoking | ||||||
| Never | 13.8 (71/515) | 6.3 (30/474) | 3.4 (15/442) | |||
| Occasionally | 14.9 (7/47) | 1.01 (0.50 to 2.05) | 7.0 (3/43) | 0.98 (0.33 to 2.89) | 2.4 (1/41) | 0.64 (0.09 to 4.42) |
| Daily ⩽10 cigs | 23.5 (27/115) | 1.55 (1.04 to 2.32) | 18.5 (20/108) | 2.18 (1.28 to 3.71) | 10.1 (9/89) | 2.42 (1.11 to 5.27) |
| Daily >10 cigs | 34.8 (31/89) | 2.19 (1.48 to 3.23) | 24.7 (19/77) | 2.63 (1.54 to 4.49) | 13.8 (9/65) | 3.05 (1.32 to 7.02) |
| Non-atopic subjects | ||||||
| Active smoking during adolescence | ||||||
| No | 5.5 (45/825) | 1.9 (15/795) | 0.8 (6/778) | |||
| Yes | 20.8 (104/500) | 3.25 (2.22 to 4.76) | 9.2 (40/436) | 3.92 (2.01 to 7.65) | 2.3 (9/399) | 2.16 (0.79 to 5.93) |
| Duration of active smoking (years) | ||||||
| Never | 5.5 (45/825) | 1.9 (15/795) | 0.8 (6/778) | |||
| ⩽2 | 14.2 (26/183) | 2.42 (1.48 to 3.98) | 6.5 (11/168) | 3.13 (1.34 to 7.33) | 1.9 (3/158) | 1.91 (0.50 to 7.32) |
| 2–4 | 23.3 (50/215) | 3.67 (2.39 to 5.63) | 9.3 (17/182) | 4.06 (1.90 to 8.68) | 2.4 (4/167) | 2.27 (0.64 to 8.06) |
| >4 | 28.4 (27/95) | 4.38 (2.70 to 7.11) | 15.0 (12/80) | 5.98 (2.68 to 13.35) | 2.9 (2/68) | 2.84 (0.59 to 13.58) |
| Intensity of active smoking | ||||||
| Never | 5.5 (45/825) | 1.9 (15/795) | 0.8 (6/778) | |||
| Occasionally | 14.6 (12/82) | 2.46 (1.34 to 4.51) | 6.7 (5/75) | 3.11 (1.12 to 8.63) | 2.9 (2/70) | 2.92 (0.61 to 14.03) |
| Daily ⩽10 cigs | 15.8 (35/222) | 2.72 (1.73 to 4.30) | 5.6 (11/198) | 2.68 (1.14 to 6.27) | 1.6 (3/187) | 1.63 (0.42 to 6.30) |
| Daily >10 cigs | 28.9 (56/194) | 4.41 (2.86 to 6.79) | 14.8 (24/162) | 6.24 (2.94 to 13.22) | 2.8 (4/141) | 2.42 (0.70 to 8.36) |