Table 1:
Baseline characteristics of study participants, by asthma status
| ALL | Controls | Cases | |
|---|---|---|---|
| N= | 638 | 308 | 330 |
| Annual 1-hr daily max SO2, ppb | 3.80 (0.88) | 3.64 (0.57) | 3.84 (0.92)** |
| Age, years | 10.2 (2.7) | 10.5 (2.7) | 10.0 (2.6)* |
| Gender, female | 302 (47%) | 158 (51%) | 144 (44%) |
| Lived at current residence, years | 7.2 (4.0) | 7.6 (4.0) | 6.9 (3.9)* |
| FVC %predicted | 103 (17) | 105 (18) | 102 (16) |
| FEV1, % predicted | 95 (15) | 98 (15) | 93 (16)** |
| FEV1/FVC, % predicted | 92 (10) | 94 (10) | 91 (10)** |
| Income >$15,000, yes | 225 (36%) | 110 (37%) | 115 (35%) |
| Distance to a major roadway, meters | 220 (324) | 287 (364) | 210 (269) |
| Current SHS exposure, yes | 252 (40%) | 104 (34%) | 148 (45%)** |
| IgE, geometric mean | 214 (4.9) | 151 (4.7) | 300 (4.8)** |
| Atopy | 331 (59%) | 135 (50%) | 196 (69%)** |
| BMI, z score | 0.59 (1.1) | 0.49 (1.1) | 0.69 (1.2)* |
| Parental history of asthma, yes | 317 (50%) | 98 (32%) | 219 (67%)** |
| Parental history of allergic rhinitis, yes | 125 (20%) | 45 (15%) | 80 (24%)** |
| Prescribed inhaled corticosteroid in last 6 months, yes | - | - | 107 (32%) |
Results reported as mean (sd), median (IQR) for SO2 and distance, or n (%). Atopy defined as at least one positive (≥0.35kU/L) specific-IgE to aeroallergen (cat, dog, dust mite, cockroach, mouse). Percent predicted calculated based on Global Lung Initiative (GLI2012) prediction equations. Analysis restricted to participants who reported living at least 1 year at current residence. P value obtained from Wilcoxon rank sum or Chi square between no asthma and asthma groups.
*
p value<0.05,
**
p value <0.01