Figure 1The selection process for the study participants. COPD = chronic obstructive pulmonary disease; FEV1/FVC = forced expiratory volume in 1 second; KNHAES = Korea National Health and Nutrition Examination Survey.
Table 1List of explanatory variables.
Variables |
Category |
General characteristics |
Sex |
Male/female |
|
Age (y) |
40–49/50–59/60–69/70–79 |
|
Education |
Elementary school or less/middle school/high school/college or more |
|
Income |
Low/middle/high |
|
Longest held job in life |
Managers, professional, office worker/service, sales worker/agriculture fishery worker, manual laborer, soldier/technician, machine operator, assembly worker |
|
Residence |
Urban/rural |
Health and environment related characteristics |
BMI (kg/m2) |
< 18.5/18.5–< 25/≥ 25 |
|
Stress |
High/moderate/low |
|
Passive smoking at work |
No/yes |
|
Passive smoking at home |
No/yes |
|
Moderate physical activity (d) |
< 3/≥ 3 |
|
Anemia |
No/yes |
|
Lead (μg/dL) |
|
|
Cadmium (μg/dL) |
|
|
History of pulmonary tuberculosis |
No/yes |
|
Time elapsed after the first diagnosis of pulmonary tuberculosis (y) |
|
Table 2Prevalence of chronic obstructive pulmonary disease (COPD) among nonsmoking adults (n = 5,489).
Year |
COPD (n = 388)
|
Non-COPD (n = 5,101)
|
Total (n = 5,489)
|
n
|
% (SE) |
n
|
% (SE) |
n
|
2010 |
92 |
6.2 (0.9) |
1,558 |
93.8 (0.9) |
1,660 |
2011 |
115 |
6.4 (0.7) |
1,714 |
93.6 (0.7) |
1,829 |
2012 |
181 |
8.0 (1.1) |
1,829 |
92.0 (1.1) |
2,010 |
Total |
388 |
6.9 (0.5) |
5,101 |
93.1 (0.5) |
5,489 |
Table 3Comparison of prevalence of chronic obstructive pulmonary disease (COPD) by general, health and environment related characteristics among nonsmoking adults. (n = 5,489).
Variable |
Categories |
Total
|
COPD (n = 388)
|
Never smoker (n = 5,489)
|
n
|
n
|
% (SE) |
Univariable R
|
OR (95% CI) |
Sex |
Male |
|
|
|
2.183 (1.562–3.051)†
|
|
Female |
4,879 |
297 |
6.1 (0.5) |
1 |
Age (y) |
40–49 |
1,473 |
28 |
2.2 (0.5) |
1 |
|
50–59 |
1,783 |
75 |
3.8 (0.5) |
1.738 (1.037–2.912)†
|
|
60–69 |
1,425 |
160 |
12.4 (1.5) |
6.173 (3.589–10.617)†
|
|
70–79 |
808 |
125 |
15.1 (1.7) |
7.734 (1.596–13.013)†
|
Education |
Elementary school or less |
1,831 |
179 |
9.9 (1.0) |
2.215 (1.320–3.717)†
|
|
Middle school |
958 |
73 |
7.7 (1.1) |
1.687 (0.991–2.870) |
|
High school |
1,632 |
79 |
4.6 (0.8) |
0.967 (0.537–1.739) |
|
College or more |
1,061 |
57 |
4.7 (1.1) |
1 |
Income |
Low |
1,189 |
73 |
6.8 (0.9) |
1 |
|
Middle |
2,725 |
186 |
6.3 (0.6) |
0.928 (0.681–1.264) |
|
High |
1,513 |
121 |
7.6 (1.0) |
1.126 (0.771–1.647) |
Longest held job in life |
Managers/professional/office worker |
1,477 |
79 |
5.1 (0.9) |
0.888 (0.526–1.499) |
|
Service/sales worker |
1,380 |
86 |
6.0 (0.9) |
1.046 (0.659–1.661) |
|
Agriculture fishery worker/ manual laborer/soldier |
1,577 |
150 |
9.1 (1.2) |
1.644 (1.047–2.581)* |
|
Technician/machine operator/assembly worker |
713 |
39 |
5.8 (1.0) |
1 |
Residence |
Urban |
4,307 |
295 |
6.6 (0.6) |
1 |
|
Rural |
1,182 |
93 |
7.7 (1.2) |
1.176 (0.795–1.740) |
BMI (kg/m2) |
< 18.5 |
69 |
7 |
15.1 (5.9) |
2.243 (0.893–5.632) |
|
18.5–< 25 |
3,424 |
265 |
7.3 (0.7) |
1 |
|
≥ 25 |
1,991 |
116 |
5.8 (0.7) |
0.784 (0.587–1.048) |
Stress |
High |
1,260 |
81 |
6.4 (0.9) |
0.568 (0.388–0.833)* |
|
Moderate |
3,282 |
209 |
6.0 (0.6) |
0.530 (0.371–0.757)* |
|
Low |
946 |
98 |
10.7 (1.4) |
1 |
Passive smoking at work |
No |
1,611 |
127 |
6.6 (0.8) |
1.158 (0.344–3.898) |
|
Yes |
1,006 |
57 |
4.8 (0.9) |
1 |
Passive smoking at home |
No |
150 |
12 |
8.2 (2.9) |
3.058 (0.852–10.974) |
|
Yes |
665 |
42 |
5.2 (1.0) |
1 |
Frequency of moderate physical activity (d) |
< 3 |
3,966 |
278 |
7.1 (0.6) |
1.163 (0.837–1.616) |
|
≥ 3 |
1,523 |
110 |
6.2 (0.9) |
1 |
Anemia |
No |
4,761 |
333 |
6.8 (0.6) |
1 |
|
Yes |
529 |
40 |
7.1 (1.4) |
1.043 (0.690–1.576) |
|
|
|
|
|
Mean ± SD |
|
Lead (μg/dL) |
|
1,567 |
100 |
2.52 ± 1.11 |
1.334 (1.057–1.683)* |
Cadmium (μg/dL) |
|
1,567 |
100 |
1.36 ± 0.56 |
0.930 (0.660–1.311) |
History of pulmonary tuberculosis |
No |
59 |
4 |
10.2 (5.5) |
1 |
|
Yes |
248 |
53 |
19.8 (3.3) |
2.168 (0.694–6.769) |
Time elapsed after the first diagnosis of pulmonary tuberculosis (y) |
|
238 |
50 |
32.9 (2.7) |
1.043 (1.009–1.089)* |
Table 4Risk factors of chronic obstructive pulmonary disease (COPD) for nonsmoking adults (n = 1,567).
Categories |
Model 1 (n = 1,567)
|
Model 2 (n = 1,567)
|
Model 3 (n = 238)
|
Multivariable R
|
Multivariable R
|
Multivariable R
|
OR (95% CI) |
OR (95% CI) |
OR (95% CI) |
General characteristics |
Sex |
Male |
|
2.539 (1.150–5.608)* |
8.894 (1.523–151.250)* |
|
Female |
|
1 |
1 |
Age (y) |
40–49 |
|
1 |
1.054 (1.017–1.202)* |
|
50–59 |
|
1.069 (0.395–2.892) |
|
|
60–69 |
|
2.697 (0.900–8.084) |
|
|
70–79 |
|
3.076 (1.82–11.437)†
|
|
Education |
Elementary school or less |
|
5.356 (1.341–21.393)* |
15.900 (0.285–885.599) |
|
Middle school |
|
4.720 (1.374–16.217)* |
25.492 (0.256–2540.273) |
|
High school |
|
2.548 (0.890–7.297) |
6.543 (0.092–463.188) |
|
College or more |
|
1 |
1 |
Longest held job in life |
Managers/professional/office worker |
|
4.789 (0.597–14.356) |
0.741 (0.044–12.473) |
|
Service/sales worker |
|
2.177 (0.838–5.657) |
1.847 (0.200–17.069) |
|
Agriculture fishery worker/ manual laborer/soldier |
|
2.156 (0.858–5.417) |
7.252 (0.553–95.169) |
|
Technician/machine operator/assembly worker |
|
1 |
1 |
Health and environment related characteristics |
Stress |
High |
0.537 (0.228–1.265) |
0.673 (0.267–1.700) |
0.050 (0.001–2.231) |
|
Moderate |
0.677 (0.325–1.411) |
0.863 (0.413–1.805) |
0.044 (0.001–1.637) |
|
Low |
1 |
1 |
1 |
Lead (μg/dL) |
|
1.336 (1.056–1.690)* |
1.137 (0.827–1.563) |
1.431 (0.536–3.820) |
Time elapsed after the first diagnosis of pulmonary tuberculosis (y) |
|
|
|
1.064 (1.100–1.133)* |