Table S2.

Multivariate analysis of risk factors for COPD in total subjects and ever-smokers

Factors	Total			Ever-smoker
	OR	95% CI	P-value	OR	95% CI	P-value
Sex
Male	5.9	4.5–7.8	<0.0001	2.6	1.5–4.5	0.001
Female	Reference			Reference
Age (years)
40–49	Reference			Reference
50–59	2.4	1.7–3.5	<0.0001	2.8	1.8–4.4	<0.0001
60–69	5.9	4.0–8.7	<0.0001	7.2	4.6–11.5	<0.0001
70–79	13.4	8.8–20.5	<0.0001	15.6	9.0–27.0	<0.0001
≥80	16.2	7.3–36.3	<0.0001	8.4	2.9–24.7	<0.0001
BMI (kg/m2)
<18.5	2.1	1.1–4.1	0.022	1.6	0.72–3.3	0.245
18.5–24.9	Reference			Reference
≥25.0	0.7	0.5–0.9	0.006	0.7	0.5–1.0	0.049
Secondhand smoking
No	Reference			Reference
Yes	1.2	0.9–1.5	0.266	1.1	0.8–1.6	0.458
Education level
High school or more	Reference			Reference
Middle school or less	1.7	1.3–2.2	<0.0001	1.6	1.2–2.2	0.005
Occupation
Manager/professional/office worker/service/sales worker	Reference			Reference
Agriculture/fishery worker	1.4	0.9–2.1	0.156	1.2	0.7–1.9	0.535
Skilled labor/machine operator	1.0	0.7–1.6	0.909	0.9	0.6–1.5	0.769
Manual laborer (construction, mining)	2.2	1.5–3.1	<0.0001	1.2	1.2–3.4	0.006
No labor	1.5	1.0–2.1	0.044	1.4	0.9–2.2	0.146
Living with partner
Yes	Reference			Reference
No	1.3	1.0–1.7	0.077	1.2	0.8–1.4	0.441
Family income
High	Reference			Reference
Low	1.0	0.8–1.3	0.929	1.0	0.81–1.54	0.764
Diabetes mellitus
No	Reference			Reference
Yes	1.2	0.8–1.6	0.382	1.2	0.8–1.7	0.297
Hypertension
No	Reference			Reference
Yes	0.7	0.6–0.9	0.003	0.6	0.5–0.8	0.002
Pulmonary tuberculosis
No	Reference			Reference
Yes	2.9	1.9–4.3	<0.0001	2.3	1.5–3.6	<0.0001
Bronchiectasis
No	Reference			Reference
Yes	2.7	1.0–7.6	0.06	1.0	0.4–2.7	0.966

Abbreviations: COPD, chronic obstructive pulmonary disease; OR, odds ratio; CI, confidence interval; BMI, body mass index.