Table III.

Calculation of the risk score and risk group.

Variable	n=1n OR	Score
Neck lymph node level involvement
No	1.940	0
Level II/III		1
Level IV		2
Maximum neck lymph node diameter
<20 mm	0.794	0
≥20 mm		1
Carotid sheath involvement
No	0.745	0
Yes		1
Risk group	Level Ib metastatic rate, %	Total score
Low, n=381	0.5	0–1
High, n=764	8.5	2–4

OR, odds ratio.