Table 2.
Mutually Adjusted Incidence Rate Ratios (95% C.I.) for the association of the incidence of asthma with the main baseline characteristics (1991/1992).
| Relative risk (IRR) | 95% C.I. | p-value | |
| Sex | |||
| Men | 1 | ||
| Women | 2.32 | 1.16–4.67 | 0.017 |
| Birth cohort * | |||
| 1946–1951 | 1 | ||
| 1951–1956 | 1.12 | 0.36–3.49 | 0.84 |
| 1956–1961 | 1.69 | 0.60–4.77 | 0.32 |
| 1961–1976 | 1.68 | 0.60–4.69 | 0.32 |
| 1966–1971 | 2.28 | 0.82–6.34 | 0.11 |
| Urban area | |||
| Suburban area | 1 | ||
| Urban area | 2.52 | 0.77–8.19 | 0.12 |
| Asthma-like symptoms** | |||
| No | 1 | ||
| Yes | 4.17 | 2.20–7.87 | <0.001 |
| Allergic rhinitis | |||
| No | 1 | ||
| Yes | 3.30 | 1.71–6.36 | <0.001 |
| Smoking habits | |||
| Non smokers | 1 | ||
| Ex-smokers | 0.49 | 0.15–1.65 | 0.25 |
| Smokers | 0.33 | 0.15–0.73 | <0.01 |
| Social class | |||
| Medium /High | 1 | ||
| Low | 1.65 | 0.77–3.52 | 0.20 |
* test for trend p ≤ 0.01
** wheezing and/or nocturnal shortness of breath and/or nocturnal tightness in the chest