Asthma incidence by sex, age group, smoking group and obesity group, each mutually adjusted, in participants without asthma or symptoms reported at baseline#
| Comparison | All incident cases | Excluding cases with age of onset prior to first survey | ||
| HR (95% CI) | p-value | HR (95% CI) | p-value | |
| Females relative to males | 1.47 (1.04–2.07) | 0.028 | 1.71 (1.17–2.48) | 0.005 |
| Age group at baseline¶ | 0.197 | 0.658 | ||
| 25–34 yrs | 1.24 (0.80–1.92) | 1.10 (0.73–1.65) | ||
| ≥35 yrs | 0.94 (0.61–1.45) | 0.87 (0.53–1.45) | ||
| Obesity group+ | 0.011 | 0.036 | ||
| Obese each survey | 2.00 (1.25–3.20) | 2.20 (1.19–4.08) | ||
| Became obese | 1.12 (0.64–1.94) | 1.21 (0.62–2.36) | ||
| Lost obesity | No estimate | No estimate | ||
| Smoking group§ | 0.0002 | 0.012 | ||
| Ex-smokers | 1.26 (0.96–1.65) | 1.33 (0.91–1.94) | ||
| Smokers | 0.67 (0.49–0.91) | 0.67 (0.41–1.08) | ||
| Quitters | 0.61 (0.33–1.11) | 0.67 (0.35–1.30) | ||
| Re-starters | 0.72 (0.35–1.47) | 0.38 (0.11–1.31) | ||
HR: hazard ratio; CI: confidence interval. #: estimated by Cox proportional hazards regression with centre as a random effect; ¶: reference 20–24 yrs; +: reference not obese either survey; §: reference nonsmokers.