The comparison of the baseline status in select biomedical indices at the point of the first examination for each subject between the exposed subjects as a whole and the controls
| Biomedical indices | Univariate analysis | P values* | Multivariate analysis | ||
| Prevalence (%) | Logistic regression model | ||||
| Exposed | Controls | OR† | 95% CI† | ||
| Respiratory symptoms‡ | |||||
| Cough #1 (7A) | 19.4 | 14.8 | 0.14 | 1.35 | (0.85 to 2.14) |
| Cough #2 (7B) | 14.8 | 11.1 | 0.19 | 1.41 | (0.84 to 2.37) |
| Chronic cough (7E) | 5.5 | 4.2 | 0.46 | 1.6 | (0.70 to 3.64) |
| Phlegm #1 (8A) | 23.7 | 20.4 | 0.34 | 1.23 | (0.81 to 1.87) |
| Phlegm #2 (8B) | 13.5 | 10.7 | 0.29 | 1.45 | (0.85 to 2.48) |
| Chronic phlegm (8E) | 8.9 | 4.2 | 0.03 | 2.62 | (1.20 to 5.70) |
| Exacerbation (9A) | 10.5 | 7 | 0.14 | 1.56 | (0.84 to 2.91) |
| Wheeze #1 (10A1) | 9.5 | 5.6 | 0.09 | 1.51 | (0.76 to 2.99) |
| Wheeze #2§ (10A2) | 2.7 | 0 | 0.01 | – | – |
| Chronic wheeze (10A3) | 0 | 0 | – | – | – |
| Breathlessness #1 (13A) | 9.7 | 11.6 | 0.45 | 1 | (0.58 to 1.73) |
| Breathlessness #2§ (13B) | 2.2 | 1.4 | 0.76 | 2.27 | (0.58 to 8.89) |
| Breathlessness #3§ (13C) | 0.4 | 0.9 | 0.59 | 0.96 | (0.13 to 7.20) |
| Biomarker abnormality | |||||
| CRP | 12 | 6 | 0.02 | 2.02 | (1.05 to 3.88) |
| IgE | 31.7 | 20.8 | 0.003 | 1.66 | (1.12 to 2.48) |
| 8OHdG§ | 1.1 | 1.8 | 0.47 | 0.68 | (0.17 to 2.78) |
| KL6§ | 0.4 | 0 | 1 | - | - |
| SPD | 3.2 | 3.4 | 0.89 | 0.91 | (0.35 to 2.37) |
| Reduced pulmonary function | |||||
| FVC | 6.5 | 6 | 0.76 | 1 | (0.49 to 2.00) |
| FEV1 | 6.1 | 2.8 | 0.06 | 2.09 | (0.83 to 5.27) |
| FEV1/FVC§ | 2.1 | 5.1 | 0.03 | 0.44 | (0.18 to 1.09) |
| Chest X-ray findings | |||||
| Fibrotic change ≥1/1 | 0 | 0 | 1 | – | – |
| Non-specific findings | 3.4 | 1.8 | 0.27 | 2.47 | (0.78 to 7.81) |
The figures in the column of prevalence represent the proportion of subjects with symptoms or positive findings in each index. The results of multivariate analyses were adjusted for the age and smoking status of the subjects. Body mass index was also used as an adjustment factor in the case of CRP.
*Probability under the hypothesis that there are no differences between the control group and exposed group as a whole examined by the χ2 test or Fisher’s exact probability method.
†OR and its 95% CIs of the exposed group to the control group, regarding the positive findings at the baseline survey.
‡The ATS-DLD-78A questionnaire code is shown in the parentheses.
§Fisher’s exact probability method was applied.
#Grade of symptom severity: cough #1 and phlegm #1: usually having the symptom; cough #2 and phlegm #2: 4–6 times a day on 4 or more days a week; wheeze #1: when having a cold; wheeze #2: occasionally apart from cold; breathlessness #1: when hurrying on the level or walking up a slight hill; breathlessness #2: having to walk slower than people your age on the level; breathlessness #3: having to stop for breath when walking at your own pace.
8OHdG, 8-hydrovy deoxy guanosine; ATS, American Thoracic Society; CRP, C reactive protein; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; IgE, immunoglobulin E; KL6, sialylated carbohydrate antigen KL-6; SPD, surfactant protein D.