Table 5 Sensitivity analysis of the association (odds ratio, 95% confidence interval) between NO2 and prevalence of chronic phlegm.
| Males | Females | |||||
|---|---|---|---|---|---|---|
| n | Per each increase in 30 μg/m3* | <20 μg/m3v >50 μg/m3† | n | Per each increase in 30 μg/m3* | <20 μg/m3v >50 μg/m3† | |
| All | 734 | 0.85 (0.56–1.31) | 0.99 (0.40–2.46) | 886 | 1.38 (0.97–1.95) | 2.71 (1.03–7.16) |
| Adjusted‡ | 639 | 0.86 (0.42–1.77) | 3.37 (0.56–20.0) | 752 | 1.76 (1.04–2.98) | 3.53 (0.72–17.2) |
| Never smokers | 266 | 1.00 (0.46–2.17) | 1.20 (0.29–5.04) | 428 | 1.49 (0.77–2.91) | 3.13 (0.75–13.1) |
| Non‐manual social class | 455 | 0.95 (0.49–1.85) | 1.29 (0.27–6.17) | 633 | 1.98 (1.26–3.11)§ | 3.98 (1.04–15.3) |
| Years education >16 | 538 | 0.82 (0.47–1.44) | 0.98 (0.32–2.97) | 604 | 1.90 (1.23–2.93)§ | 5.81 (1.22–27.7) |
| Centres with participation rate above the median | 483 | 0.84 (0.54–1.30) | 1.03 (0.38–2.85) | 537 | 1.34 (0.89–2.02) | 2.29 (0.72–7.28) |
| Average of two NO2 periods† | 302 | 0.95 (0.44–2.03) | 1.02 (0.18–5.71) | 356 | 1.22 (0.56–2.66) | 3.35 (0.59–19.1) |
*Adjusted for season.
†Interquartile change. Adjusted for day of week and interval between the two measures.
‡Adjusted for age, smoking, social class, rhinitis, early respiratory infections, and centre. Data from Anstwerp and Tartu dropout from the model due to small numbers.
§p for interaction with social class or education <0.05.