Distribution of smoking in cases and controls, and adjusted odds ratio (OR) of asthma in relation to smoking, The Finnish Environment and Asthma Study 1997–2000
| Cases | Controls | OR# (95% CI) | |
| Total n | 518 | 930 | |
| Smoking¶ | |||
| Never-smoker | 239 (46.1) | 487 (52.4) | 1.00 |
| Ex-smoker | 133 (25.7) | 203 (21.8) | 1.49 (1.12–1.97) |
| Current | 146 (28.2) | 240 (25.8) | 1.33 (1.00–1.77) |
| Smoking rate+ cigarettes·day−1 | |||
| Never-smoker | 239 (46.1) | 487 (52.4) | 1.00 |
| Ex-smoker | 133 (25.7) | 203 (21.8) | 1.46 (1.10–1.95) |
| Occasional | 31 (6.0) | 50 (5.4) | 1.25 (0.76–2.06) |
| 1–14 | 55 (10.6) | 59 (6.3) | 1.93 (1.26–2.95) |
| ≥15 | 57 (11.0) | 122 (13.1) | 1.05 (0.71–1.56) |
| Cumulative smoking§ cigarette-years | |||
| Never-smoker | 239 (46.1) | 487 (52.4) | 1.00 |
| Ex-smoker | 133 (25.7) | 203 (21.8) | 1.47 (1.11–1.96) |
| Occasional | 31 (6.0) | 50 (5.4) | 1.25 (0.76–2.06) |
| 1–199 | 37 (7.1) | 53 (6.0) | 1.46 (0.90–2.37) |
| ≥200 | 73 (14.1) | 127 (13.7) | 1.31 (0.91–1.89) |
Data are presented as n and n (%), unless otherwise stated
CI: confidence interval
#: adjusted for sex, age, parental atopy/asthma, education, environmental tobacco smoke at home or at work, dampness and mould problems at home or at work, self-reported occupational exposures and pets
¶: data missing for three cases and two controls
+: data missing for three cases and nine controls
§: data regarding cigarette-years among daily smokers was missing for five cases and 10 controls