2.

Univariate and multivariate analysis of 710 PTMC primary sites with US features for predicting skip metastasis of lymph nodes

Features	Cases	Patients [n (%)]		χ2	P	Multivariate model
		LNs (–)	LNs (+)			Odds ratio	95% CI	P
Size (cm)				11.427	0.000	8.640	2.007–37.192	0.004
≤ 0.5	159	157 (98.7)	2 (1.3)
> 0.5, ≤ 1	551	500 (90.7)	51 (9.3)
Taller-than-wide				5.275	0.023	2.572	1.083–6.108	0.032
< 1	189	182 (96.3)	7 (3.7)
≥ 1	521	475 (91.1)	46 (8.9)
Peripheral vascularity				1.230	0.289	1.751	0.547–5.606	0.345
No	678	629 (92.8)	49 (7.2)
Yes	32	28 (87.5)	4 (12.5)
Location				21.843	0.000	0.531	0.378–0.745	0.000
Isthmus	17	17 (100.0)	0 (0.0)
Upper	249	219 (88.0)	30 (12.0)
Middle	168	151 (90.0)	17 (10.0)
Lower	276	270 (97.8)	6 (2.2)
Echogenicity				1.391	0.348	1.363	0.388–4.786	0.629
Hyper or isoechoic	74	71 (95.9)	3 (4.1)
Hypo-echoic	636	586 (92.1)	50 (7.9)
Calcification				3.977	0.029	1.722	0.759–3.903	0.193
No	190	182 (95.8)	8 (4.2)
Yes	520	475 (91.3)	45 (8.7)
Margin				0.234	0.789	0.636	0.167–2.422	0.507
Clear	52	49 (94.2)	3 (5.8)
Unclear	658	608 (92.4)	50 (7.6)
Abutment/perimeter				18.421	0.000	7.083	2.488–20.164	0.000
≤ 0.25	245	241 (98.4)	4 (1.6)
> 0.25	465	416 (89.5)	49 (10.5)