Table S6. Characteristics of COPD patients without active smoking by medium-term SHS exposure based on FEV1/FVC < LLN.
| Characteristic variables | Medium-term SHS exposure† | P value | |
|---|---|---|---|
| No | Yes | ||
| Sample size | 123 | 93 | – |
| Estimated population (weighted)‡ | 1,798,094 | 1,093,623 | – |
| Age, mean (SE), years | 61.80 (1.32) | 61.42 (1.48) | 0.85 |
| Male, % | 64.64 | 49.16 | 0.08 |
| Ethnicity, % | 0.35 | ||
| Non-Hispanic white | 87.46 | 83.42 | |
| Non-Hispanic black | 6.11 | 10.83 | |
| Mexican-American and other | 6.43 | 5.75 | |
| Marital status, % | 0.01* | ||
| Married or living with partner | 86.30 | 68.98 | |
| Other | 13.70 | 31.02 | |
| Education of college or above, % | 63.65 | 47.96 | 0.04* |
| Family income-to-poverty ratio grading, % | <0.01* | ||
| High (>3.50) | 65.92 | 33.25 | |
| Middle (>1.30–3.50) | 19.90 | 38.83 | |
| Low (0.00–1.30) | 6.27 | 18.01 | |
| Missing | 7.91 | 9.91 | |
| BMI grading, % | 0.62 | ||
| Obese (≥30 kg/m2) | 23.20 | 30.96 | |
| Overweight (25–29.9 kg/m2) | 44.37 | 42.88 | |
| Normal or underweight (<25 kg/m2) | 29.39 | 25.07 | |
| Missing | 3.04 | 1.09 | |
| Smoking history, % | 0.04* | ||
| Former | 60.96 | 78.82 | |
| Never | 39.04 | 21.18 | |
| Pack-years among former smokers, mean (SE) | 33.01 (4.43) | 40.85 (5.09) | 0.25 |
| Self-report SHS at home, % | 0.03* | ||
| Yes | 0.00 | 9.50 | |
| No | 100.00 | 90.12 | |
| Missing | 0.00 | 0.38 | |
| Self-reported SHS at the workplace, % | 0.39 | ||
| Yes | 7.11 | 2.76 | |
| No | 49.63 | 46.18 | |
| Unemployed | 43.26 | 51.06 | |
| FEV1, mean (SE), L/s | 2.65 (0.12) | 2.29 (0.16) | 0.07 |
| GOLD grading, % | 0.33 | ||
| 1 | 51.08 | 37.98 | |
| 2 | 26.95 | 37.42 | |
| 3 or 4 | 8.27 | 13.26 | |
| Missing | 13.70 | 11.34 | |
| Comorbidities | |||
| Asthma, % | 28.91 | 23.57 | 0.49 |
| Cancer, % | 30.06 | 25.08 | 0.58 |
| Stroke, % | 5.06 | 4.70 | 0.93 |
| Hypertension, % | 60.42 | 45.64 | 0.07 |
| Coronary heart disease, % | 15.17 | 14.23 | 0.83 |
| Heart failure, % | 6.41 | 7.18 | 0.84 |
| Diabetes, % | 13.13 | 16.49 | 0.54 |
| Sedentary time per day, mean (SE), minutes | 382.39 (22.92) | 359.99 (20.98) | 0.48 |
| Only inhaling bronchodilator, % | 5.48 | 21.15 | 0.03* |
| Inhaling bronchodilator and corticosteroid, % | 18.68 | 10.94 | 0.20 |
Data obtained from the National Health and Nutrition Examination Survey (2007–2012), National Center for Health Statistics. †, 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 lung disease; FEV1, forced expiratory volume in 1 second; FVC, forced vital capacity; LLN, lower limit of normal; SHS, secondhand smoke; SE, standard error; BMI, body mass index; GOLD, Global Initiative for Chronic Obstructive Lung Disease.