Table 4A.

The incidence rate of LLNM in derivation and internal validation cohort patients with different total points.

Total points	LLNM		Total	The incidence rate of LLNM
	negative (−)	positive (+)		(LLNM+)/Total (%)
0, 100, 110	144	37	181	20.4
200, 210	29	37	66	56.1
300, 310	22	40	62	64.5
400, 410	2	24	26	92.3
510	0	1	1	100

According to the total points and corresponding incidence rate of LLNM, we stratified PTC patients into three subgroups: low-risk LLNM subgroup (total points = 0, 100, 110), moderate-risk subgroup (total points = 200, 210, 300, 310), and high-risk subgroup (total points = 400, 410, 510). We applied this risk stratification to the prospective validation cohort.