Table 4. Univariable and multivariable analyses for progression-free survival.

	Univariable analysis			Multivariable analysisa
	HR	95% CI	P	HR	95% CI	P
Age	0.992	0.963–1.022	0.606	ND
Sex (male as reference)	0.899	0.368–2.194	0.815	ND
T-classification
T1/T2 vs. T3/T4	0.357	0.168–0.759	0.007	0.363	0.170–0.761	0.009
N-classification
N0/N1 vs. N2/N3	0.708	0.347–1.446	0.343	ND
Overall stage
I/II vs. III/IVA-B	0.437	0.179–1.066	0.069	0.456	0.176–1.131	0.110
IMRT alone	2.632	0.628–10.989	0.186	ND
Concurrent chemoradiation	0.643	0.225–1.838	0.410	ND
Induction chemotherapy then concurrent chemoradiation	0.335	0.160–0.702	0.014	0.401	0.205–1.563	0.254
Concurrent chemoradiation then adjuvant chemotherapy	0.820	0.404–1.664	0.582	ND
PD-L1 expression level
PD-L1 1+	0.386	0.135–1.104	0.076	0.398	0.140–1.108	0.056
PD-L1 2+	0.346	0.105–1.010	0.067	0.351	0.108–0.999	0.045

Abbreviations: CI, confidence interval; HR, hazard ratio; IMRT, intensity-modulated radiation therapy; ND, not done; PD-L1, programmed death-ligand 1.

^aOnly covariates found significant (P < 0.1) in the univariable analysis were considered in the multivariable analysis.