Table 5. Risk factors for COPD in participants older than 65 years (n=888).

Risk factors	Odds ratio (95% CI)	P
Univariate analysis
Age (years)	1.1 (1.02–1.09)	0.003
Male	4.8 (3.45–6.78)	<0.001
Smoking amount (pack-year)	1.0 (1.02–1.03)	<0.001
BMI	0.9 (0.83–0.92)	<0.001
Education status		0.097
University	Reference
High school	1.5 (0.84–2.68)
Middle school	1.4 (0.84–2.32)
Elementary school	1.6 (1.03–2.63)
History of pulmonary tuberculosis	2.1 (1.25–3.44)	0.005
Living below the poverty line	1.4 (1.02–1.91)	0.037
Multivariate analysis
Male	3.6 (2.36–5.55)	<0.001
Smoking amount (pack-year)	1.0 (1.00–1.02)	0.027
BMI	0.9 (0.86–0.97)	0.002
Living below the poverty line	1.5 (1.06–2.13)	0.021

Multivariate logistic regression analysis using backward elimination was performed to evaluate the association between living below the poverty line and the prevalence of COPD, after adjusting for age, sex, smoking amount, BMI, and the history of pulmonary tuberculosis. BMI, body mass index; COPD, chronic obstructive pulmonary disease.