Associations from a conditional logistic regression analysis of the impact of traffic flow, outdoor nitrogen dioxide(NO2) and urban versus rural living on the risk for developing asthma
| All participants | Lived > 2 yrs in present home | |||||
| Subjects n | OR | 95% CI | Subjects n | OR | 95% CI | |
| Conditional logistic regression | ||||||
| Traffic flow | ||||||
| Low | 379 | 1# | 208 | 1# | ||
| High | 1.5# | 0.9–2.5 | 2.4# | 0.9–6.2 | ||
| Outdoor NO2 µg·m-3 | 261 | 1.0# | 0.9–1.1 | 156 | 1.1# | 0.9–1.2 |
| Degree of urbanisation | ||||||
| Urban | 379 | 1¶ | 208 | 1¶ | ||
| Rural | 1.6¶ | 0.9–3.1 | 2.1¶ | 0.8–5.6 | ||
| Urban | 261 | 1+ | 156 | 1+ | ||
| Rural | 1.5+ | 0.7–3.3 | 2.0+ | 0.6–6.3 | ||
| Logistic regression | ||||||
| Outdoor NO2 µg·m-3 | ||||||
| Negative SPT | 117 | 1.0§ | 0.9–1.1 | |||
| Positive SPT | 67 | 1.2§ | 1.0–1.3 | |||
The table shows results for an unconditional analysis of NO2 made among those with positive and negative skin-prick tests (SPT), separately. Results are shown for analyses including all participants and those restricted to persons who lived >2 yrs in their present home separately. OR: odds ratio; 95% CI: 95% confidence intervals. #: adjusted for rural residence, SPT, family history of asthma, body mass index (BMI) and smoking; ¶: adjusted for traffic flow, SPT, family history of asthma, BMI and smoking; +: adjusted for NO2, SPT, family history of asthma, BMI and smoking; §: adjusted for age, sex, rural residence, family history of asthma, BMI and smoking.