Odds Ratios (ORs) of developing asthma according to changes in smoking habits at second and third examination
| Smoking categories at follow-up | 5-yr follow-up | 10-yr follow-up | ||||
| Subjects (n) | OR (95% CI) Crude* | Adjusted** | Subjects (n) | OR (95% CI) Crude* | Adjusted** | |
| Never-smokers | 2149 | 1 | 1 | 1678 | 1 | 1 |
| Persistent quitters | 1581 | 1.5 (0.6–3.3) | 1.2 (0.5–2.8) | 1285 | 1.3 (0.8–2.1) | 1.2 (0.8–2.0) |
| New quitters | 657 | 4.8 (2.3–10.0) | 3.9 (1.8–8.2) | 659 | 4.2 (2.6–6.7) | 3.1 (1.9–5.1) |
| Continuing smokers | 5552 | 2.3 (1.2–4.3) | 2.6 (1.2–5.5) | 3039 | 2.8 (1.9–4.2) | 2.0 (1.3–3.0) |
| Starters | 261 | 2.1 (0.7–6.0) | 2.0 (0.7–5.6) | 153 | 1.7 (0.7–5.6) | 1.7 (0.7–4.6) |
*: adjusted for sex and age
**: fully adjusted regression model including sex, age, pack-yrs, chronic bronchitis and level of forced expiratory volume in one second
Numbers are not equal due to losses of follow-up (death and nonresponse)