Crude risk ratios (RR) of developing respiratory symptoms† according to characteristics at baseline in asymptomatic subjects at baseline (univariate analyses)
| Characteristics | No of subjects with incident respiratory symptoms | RR (95% CI) |
|---|---|---|
| AHR, airway hyperresponsiveness; PC20, concentration of methacholine provoking a 20% fall in FEV1; RR, risk ratio; CI, confidence interval. | ||
| *p<0.05; **p<0.01; ***p<0.001. | ||
| †At least two of the following symptoms: wheezing, shortness of breath, chest tightness, cough, respiratory complaints upon exertion. | ||
| ‡Skin reaction to two or more common aeroallergens. | ||
| §Urticaria, eczema, or hay fever. | ||
| AHR (PC20 ⩽8 v>8 mg/ml) | 13 | 6.02 (2.80 to 12.92)*** |
| Current smoking | 3 | 0.73 (0.21 to 2.48) |
| Atopy‡ | 23 | 2.38 (1.26 to 4.50)* |
| Atopic diathesis§ | 9 | 1.13 (0.52 to 2.46) |
| Self-reported rhinitis | ||
| Non-specific | 31 | 4.11 (2.08 to 8.11)*** |
| To animals | 23 | 4.66 (2.45 to 8.89)*** |
| To pollen | 17 | 3.03 (1.56 to 5.88)** |
| Ownership of a pet at any time | 41 | 1.24 (0.36 to 4.24) |
| Family history of asthma | 14 | 2.29 (1.15 to 4.56)* |