Incidence rates of asthma (cases per 1,000 person-years under observation) in 1989–2001 in relation to respiratory symptoms at start of follow-up
| Symptom at start of follow-up | Exclusion criteria | |||
| Wheezing | Wheezing or nocturnal dyspnoea | Wheezing, nocturnal dyspnoea or chest tightness | Wheezing, nocturnal dyspnoea, chest tightness or cough | |
| Nocturnal dyspnoea | ||||
| Yes | 5.0 (2.7–8.5) | |||
| No | 1.7 (1.4–1.9) | |||
| Nocturnal chest tightness | ||||
| Yes | 3.5 (2.1–5.5) | 2.2 (1.0–4.1) | ||
| No | 1.7 (1.4–1.9) | 1.7 (1.5–2.0) | ||
| Nocturnal cough | ||||
| Yes | 2.6 (2.0–3.3) | 2.4 (1.8–3.1) | 2.3 (1.7–3.1) | |
| No | 1.5 (1.3–1.7) | 1.5 (1.3–1.7) | 1.5 (1.0–2.0) | |
| Allergic rhinitis | ||||
| Yes | 3.8 (2.9–4.8) | 3.7 (2.9–4.8) | 3.7 (2.8–4.7) | 3.4 (2.5–4.7) |
| No | 1.4 (0.95–1.9) | 1.3 (0.88–1.8) | 1.3 (0.93–1.8) | 1.2 (0.94–1.4) |
| All | 1.7 (1.5–2.0) | 1.7 (1.5–2.0) | 1.6 (1.2–2.2) | 1.5 (1.0–2.0) |
Data are presented as incident rate ratio (95% confidence interval (CI))