Modification of associations* between NO2 (per IQR of 5.8 μg/m3) and first asthma hospital admissions (n=977) by baseline characteristics and comorbid conditions among the 53 695 Diet, Cancer and Health cohort participants
| Covariates | Covariate level | n | Hospitalisation rate† | HR (95% CI) | p Value‡ |
| Gender | Male | 385 | 1.5 | 1.19 (0.97 to 1.40) | 0.30 |
| Female | 612 | 2.2 | 1.09 (0.99 to 1.19) | ||
| Smoking status | Never | 309 | 1.6 | 1.05 (0.90 to 1.20) | 0.31 |
| Previous | 318 | 2.1 | 1.17 (0.88 to 1.47) | ||
| Current | 370 | 1.9 | 1.15 (0.85 to 1.43) | ||
| ETS | Yes | 686 | 2.0 | 1.16 (0.88 to 1.44) | 0.24 |
| No | 311 | 1.6 | 1.04 (0.89 to 1.19) | ||
| Occupational exposure | Yes | 390 | 2.3 | 1.07 (0.85 to 1.28) | 0.28 |
| No | 607 | 1.6 | 1.17 (1.06 to 1.27) | ||
| COPD (n=2139) | Yes | 219 | 11.0 | 1.30 (1.07 to 1.52) | 0.04 |
| No | 778 | 1.5 | 1.07 (0.98 to 1.17) | ||
| IHD (n=5458) | Yes | 91 | 1.8 | 1.00 (0.70 to 1.30) | 0.35 |
| No | 901 | 1.9 | 1.14 (1.06 to 1.22) | ||
| Stroke (n=2542) | Yes | 22 | 0.9 | 0.86 (0.27 to 1.46) | 0.36 |
| No | 975 | 1.9 | 1.13 (1.05 to 1.21) | ||
| Diabetes (n=5283) | Yes | 72 | 1.3 | 0.87 (0.53 to 1.21) | 0.08 |
| No | 925 | 1.9 | 1.15 (1.07 to 1.23) |
↵* Fully adjusted for smoking status (never, previous, current), smoking intensity, smoking duration, ETS, occupational exposure, gender, body mass index and educational level.
↵† Crude hospitalisation rate per 1000 person-years.
↵‡ For Wald test for interaction.
COPD, chronic obstructive pulmonary disease; ETS, environmental tobacco smoke; IHD, ischaemic heart disease; NO2, nitrogen dioxide.