Table 1.
Main characteristics of study participants, by current wheeze1
| Characteristics | Control subjects2 (n = 11,767) |
Current wheeze3 (n = 2,121) |
|---|---|---|
| Age, years | 45.7 ± 0.4 | 46.6 ± 0.4 * |
| Female gender | 5912 (50.4) | 1135 (54.3) ** |
| Race | ||
| Non-Hispanic White | 4833 (66.9) | 1056 (70.8) ** |
| Mexican American | 2106 (9.4) | 213 (5.1) |
| Other Hispanic | 1312 (5.8) | 195 (4.7) |
| Non-Hispanic Black | 2414 (10.6) | 519 (13.1) |
| Other | 1102 (7.3) | 138 (6.2) |
| Had health insurance coverage | 8662 (79.1) | 1600 (79.0) |
| Annual household income ≥ $20,000 | 8920 (86.5) | 1380 (77.8) ** |
| Smoking status | ||
| Never/former smoker | 9481 (81.5) | 1261 (59.0) ** |
| Current smoker | 2286 (18.5) | 860 (41.0) |
| Body mass index (BMI) | 28.4 ± 0.1 | 30.5 ± 0.2 ** |
| Serum cotinine level, ng/mL | 50.9 ± 2.6 | 112.4 ± 5.1 ** |
| Family history of asthma | 1796 (15.6) | 738 (34.3) ** |
| Vitamin D insufficiency (<30 ng/mL) | 7887 (62.2) | 1468 (67.6) ** |
| Use oral or inhaled steroid in past 2 days | 121 (1.3) | 339 (19.9) ** |
| Occupation exposure to mineral dusts or exhaust fumes | 4233 (36.7) | 1081 (50.0) ** |
| Serum level of heavy metals | ||
| Cadmium, μg/L | 0.47 ± 0.01 | 0.82 ± 0.04 ** |
| Lead, μg/L | 1.54 ± 0.04 | 1.65 ± 0.05 * |
| Lung function | ||
| Percent predicted FEV1 | 98.8 ± 0.3 | 88.5 ± 0.6 ** |
| Percent predicted FVC | 102.1 ± 0.2 | 96.7 ± 0.5 ** |
| Percent predicted FEV1/FVC | 96.5 ± 0.1 | 90.8 ± 0.4 ** |
| Fractional exhaled nitric oxide (FeNTO), ppb | 16.7 ± 0.3 | 21.1 ± 0.8 ** |
1
Values are presented as number (%) or mean (mean ± standard deviation)
2
Control subjects had neither current wheeze nor an asthma diagnosis
3
Wheeze or whistling in the chest in the previous 12 months.
4
* P< 0.05 and ** P< 0.01 for the comparison of subjects with current wheeze with control subjects.