Table 2. Multivariate analysis of the lymph node ratio (LNR) and covariates associated with survival of laryngeal cancer cases with lymph node metastasis.

Variables	Cause specific survival		Overall survival
	HR(95% CI)	P value	HR(95% CI)	P value
Race (White as reference)
Black	1.212(1.041–1.412)	0.013	1.238(1.084–1.413)	0.001
Other	0.920(0.674–1.252)	0.592	0.858(0.652–1.123)	0.261
Radiation sequence (no radiation as reference)
Pre-operative	0.846(0.606–1.182)	0.328	0.839(0.627–1.123)	0.238
Post-operative	0.694(0.599–0.805)	<0.001	0.654(0.577–0.743)	<0.001
Other	0.976(0.556–1.714)	0.932	0.952(0.574–1.579)	0.848
T classification (T1 as reference)
T2	1.308(1.013–1.689)	0.040	1.277(1.033–1.577)	0.024
T3	1.740(1.316–2.301)	<0.001	1.540(1.216–1.951)	<0.001
T4a	1.856(1.450–2.375)	<0.001	1.630(1.327–2.002)	<0.001
T4b	2.365(1.574–3.552)	<0.001	2.157(1.526–3.048)	<0.001
Tx	1.963(1.285–3.001)	0.002	1.725(1.186–2.511)	0.004
N classification (N1 as reference)
N2	1.948(1.668–2.274)	<0.001	1.642(1.445–1.865)	<0.001
N3	1.806(1.358–2.402)	<0.001	1.668(1.309–2.127)	<0.001
M classification (M0 as reference)
M1	1.700(1.194–2.420)	0.003	1.579(1.137–2.195)	0.006
MX	0.722(0.386–1.349)	0.307	0.864(0.510–1.466)	0.588
LNR as continuous variable	2.299(1.905–2.775)	<0.001	1.810(1.532–2.138)	<0.001
Age	1.013(1.006–1.019)	<0.001	1.020(1.014–1.025)	<0.001