Table 2.

Univariate analysis of risk factors for central lymph node metastasis

		OR	95%CI		P value
			Lower	Upper
Gender	(male vs. female)	1.59	1.16	2.18	0.004
Age (years)					< 0.001a
	≤35	4.19	2.79	6.28	< 0.001
	35–45	2.15	1.44	3.51	< 0.001
	45–55	1.28	0.85	1.91	0.240
	> 55	1
Tumor size(cm)					< 0.001a
	≤0.5	1
	0.5–1.0	1.86	1.20	2.89	0.006
	1.0–2.0	4.24	2.71	6.62	< 0.001
	> 2.0	6.78	4.11	11.18	< 0.001
Ultrasound feature
Microcalcification	(yes vs. no)	1.59	1.19	2.13	0.002
Hypoechoic solid nodules	(yes vs. no)	0.96	0.69	1.33	0.803
Irregular shape	(yes vs. no)	1.21	0.92	1.58	0.176
Infiltrative margins	(yes vs. no)	1.04	0.77	1.40	0.793
Intra-nodular vascularity	(yes vs. no)	1.64	1.24	2.18	0.001
Multifocality	(yes vs. no)	1.45	1.10	1.92	0.009
Bilateral	(yes vs. no)	1.50	1.09	2.06	0.012
Extrathyroidal extension	(yes vs. no)	2.11	1.54	2.88	< 0.001
Distant metastasis	(yes vs. no)	6.59	0.73	59.19	0.092
Hashimoto’s thyroiditis	(yes vs. no)	1.19	0.91	1.56	0.195
TSH value		1.01	0.93	1.10	0.799

^a means the global p-values