Table 4.

Univariable-adjusted and multivariable-adjusted odds ratios of chronic obstructive pulmonary disease associated with risk factors.

Variables	Univariable-adjusted		Multivariable-adjusted
	OR (95% CI)	P-value	OR (95% CI)	P-value
Male gender	1.12 (0.91–1.39)	0.275	1.25 (0.96–1.62)	0.095
Age, years
15–39	1.00 (Reference)		1.00 (Reference)
≥40	3.03 (2.40–3.82)	<0.0001	2.25 (1.72–2.95)	<0.0001
Altitude,m
2,100–3,000	1.00 (Reference)		1.00 (Reference)
3,000–4,000	0.57 (0.44–0.73)	<0.0001	0.61 (0.46–0.79)	<0.0001
>4,000	0.46 (0.35–0.62)	<0.0001	0.45 (0.33–0.61)	<0.0001
Education level
Primary school and lower	1.00 (Reference)		1.00 (Reference)
Middle and high school	0.38 (0.28–0.52)	<0.0001	0.49 (0.35–0.68)	<0.0001
College and higher	0.38 (0.27–0.53)	<0.0001	0.64 (0.43–0.95)	0.025
Pack–years of smoking
0	1.00 (Reference)		1.00 (Reference)
1–19	0.87 (0.42–1.80)	0.714	1.22 (0.58–2.57)	0.609
≥20	1.49 (1.18–1.88)	0.001	1.21 (0.91–1.60)	0.191
Household air pollution	1.82 (1.42–2.40)	<0.0001	1.34 (1.01–1.79)	0.043
History of tuberculosis	2.28 (1.58–3.29)	<0.0001	1.79 (1.23–2.61)	0.030
Exposure to dust or chemicals in the workplace	1.56 (0.90–2.70)	0.108	1.19 (0.67–2.10)	0.558