Table 3.

Multivariate analysis of independent risk factors

Variables	β	Wald χ2	P	OR	95% CI
Age
18–29 years				1.000 (reference)
30–39 years	−0.1680	0.4464	0.5040	0.845	0.516–1.384
40–49 years	−0.0069	0.0005	0.9825	0.993	0.533–1.849
50–59 years	−0.4201	1.1700	0.2794	0.657	0.307–1.406
≥60 years	−0.3139	0.4902	0.4839	0.731	0.303–1.759
Han	0.5398	1.6170	0.2035	1.716	0.747–3.942
Smoking status
Non-smoker				1.000 (reference)
Former-smoker	0.0136	0.0008	0.9768	1.014	0.406–2.533
Current-smoker	2.5121	160.9172	<0.001	12.331	8.364–18.179

Logistic regression was used to explore the related factors. OR: Odds ratio; CI: Confidence interval.