| Risk factor | OR | 95% CI | p-value |
| Undiagnosed wheeze | |||
| Rhinitis at 18 yrs | 2.82 | 1.38–5.73 | 0.004 |
| Teenage smoking (past or current)# | 2.54 | 1.19–5.41 | 0.02 |
| Paracetamol use at 18 yrs¶ | 1.11 | 1.01–1.23 | 0.03 |
| Family history of asthma+ | 2.26 | 1.10–4.63 | 0.03 |
| Asthma | |||
| Family history of asthma+ | 1.74 | 1.14–2.66 | 0.01 |
| Atopy at 4 yrs§ | 3.98 | 2.52–6.28 | <0.001 |
| Rhinitis at 10 yrs | 3.97 | 2.57–6.14 | <0.001 |
| Paracetamol use at 18 yrs¶ | 1.10 | 1.03–1.17 | 0.005 |
Factors for undiagnosed wheeze and asthma showing trends for significance at univariate analysis (p<0.1) were entered en bloc into separate logistic regression models to identify independent risk factors for each group. Factors entered for undiagnosed wheeze included female sex, family history of asthma, home tobacco exposure during pregnancy, atopy at 4 yrs, teenage smoking, paracetamol use at 18 yrs, nonsteroidal anti-inflammatory drug use at 18 yrs, and rhinitis at 18 yrs. Factors entered for asthma included female sex, family history of asthma, asthma/wheeze at 1 or 2 yrs, chest infections at 1 or 2 yrs, teenage smoking (past or current), atopy at 4 yrs, rhinitis at 10 yrs, paracetamol use at 18 yrs and number of days of exercise at 18 yrs. Factors showing multivariate significance (p<0.05) are shown. #: self smoking status current or past was determined at the 18 yr follow-up; ¶: number of times (median values) paracetamol used per month; +: family history of asthma, determined at birth from parents; §: atopy defined by at least 1 skin test wheal response >3 mm diameter.