Table 1. Characteristics of COPD patients without active smoking by medium-term SHS exposure.
| Characteristic variables† | Medium-term SHS exposure | P value | |
|---|---|---|---|
| No | Yes | ||
| Sample size | 209 | 125 | – |
| Estimated population (weighted)‡ | 3,063,227 | 1,642,858 | – |
| Age groups, % | 0.15 | ||
| 40–59 years | 34.96 | 46.73 | |
| ≥60 years | 65.04 | 53.27 | |
| Male, % | 63.26 | 62.02 | 0.88 |
| Ethnicity, % | 0.03* | ||
| Non-Hispanic white | 86.40 | 87.20 | |
| Non-Hispanic black | 4.20 | 8.44 | |
| Mexican-American and other | 9.40 | 4.36 | |
| Education, % | 0.04* | ||
| College or above | 70.14 | 56.89 | |
| High school or below | 29.86 | 43.11 | |
| Family income-to-poverty ratio grading, % | <0.01* | ||
| High (>3.50) | 61.77 | 38.52 | |
| Middle (>1.30–3.50) | 22.42 | 37.01 | |
| Low (0.00–1.30) | 6.33 | 15.92 | |
| Missing | 9.48 | 8.55 | |
| Smoking history, % | <0.01* | ||
| Former | 53.30 | 78.30 | |
| Never | 46.70 | 21.70 | |
| Self-reported SHS at home, % | <0.01* | ||
| Yes | 0.57 | 9.91 | |
| No | 98.71 | 89.84 | |
| Missing | 0.72 | 0.25 | |
| GOLD grading, % | 0.08 | ||
| 1 | 62.84 | 44.25 | |
| 2 | 23.29 | 38.00 | |
| 3 or 4 | 5.83 | 10.38 | |
| Missing | 8.04 | 7.37 | |
| Only inhaling bronchodilator | 0.03* | ||
| Yes | 3.22 | 14.35 | |
| No | 96.78 | 85.65 | |
Data obtained from the National Health and Nutrition Examination Survey (2007–2012), National Center for Health Statistics. †, except for age group, gender, and GOLD grading, other non-significant characteristics are listed in Table S3. Because the sample weights led to inconsistencies with the proportions in cells, the patient counts are not shown; ‡, estimated population (weighted) means the population size represented by the sample size; *, statistical significance at the P<0.05 level when comparing between two groups. COPD, chronic obstructive pulmonary disease; GOLD, Global Initiative for Chronic Obstructive Lung Disease; SHS, secondhand smoke.