Table 2. Summary of important prognostic factors in multivariate analysis.

	The original unmatched cohort		The propensity-matched cohort
	Hazard ratio (95% CI)	P †	Hazard ratio (95% CI)	P ‡
Overall survival
IMRT alone versus IMRT+CC	0.64 (0.31–1.31)	0.224	0.70 (0.34–1.44)	0.328
Age (continuous)	1.06 (1.03–1.09)	< 0.001	1.05 (1.011.10)	0.011
Sex	0.92 (0.43–1.99)	0.833	0.82 (0.26–2.55)	0.731
Histology	0.53 (0.16–1.80)	0.310	0.92 (0.10–8.03)	0.936
VCA-IgA	0.83 (0.45–1.53)	0.554	0.54 (0.27–1.07)	0.076
EA-IgA	1.20 (0.66–2.19)	0.554	1.77 (0.91–3.43)	0.091
T-stage	1.10 (0.53–2.28)	0.789	1.14 (0.48–2.70)	0.773
N-stage	1.06 (0.40–2.78)	0.913	0.72 (0.28–1.86)	0.499
Distant metastasis-free survival
IMRT alone versus IMRT+CC	0.60 (0.26–1.42)	0.248	0.69 (0.30–1.58)	0.383
Age (continuous)	1.01 (0.97–1.04)	0.677	1.04 (0.99–1.10)	0.127
Sex	0.43 (0.15–1.26)	0.125	0.53 (0.15–1.91)	0.333
Histology	0.46 (0.11–1.95)	0.290	-	-
VCA-IgA	0.70 (0.34–1.46)	0.341	0.41 (0.18–0.92)	0.032
EA-IgA	1.72 (0.87–3.43)	0.122	2.08 (0.98–4.45)	0.058
T-stage	1.14 (0.50–2.62)	0.496	1.11 (0.37–3.32)	0.858
N-stage	2.17 (0.65–7.27)	0.210	1.36 (0.35–5.30)	0.661
Locoregional relapse-free survival
IMRT alone versus IMRT+CC	1.01 (0.52–1.97)	0.974	0.82 (0.40–1.67)	0.586
Age (continuous)	1.01 (0.98–1.04)	0.617	1.00 (0.97–1.04)	0.941
Sex	1.72 (0.90–3.30)	0.099	1.67 (0.82–3.38)	0.158
Histology	-	-	-	-
VCA-IgA	1.13 (0.62–2.03)	0.695	0.99 (0.52–1.88)	0.980
EA-IgA	0.82 (0.46–1.46)	0.505	0.89 (0.46–1.71)	0.724
T-stage	1.57 (0.78–3.16)	0.207	1.74 (0.84–3.58)	0.133
N-stage	2.35 (0.87–6.39)	0.093	1.89 (0.69–5.23)	0.218

Abbreviations: CI = confidence interval, CC = concurrent chemotherapy, IMRT = intensity-modulated radiotherapy, VCA = viral capsid antigen, EA = early antigen, IgA = immunoglobulin A

^†Adjusted for age (continuous), sex, histology, VCA-IgA (<80/80–320/≥ 320), EA-IgA (<10/10–40/≥ 40), T-stage and N-stage.

^‡Adjusted for the same covariates with a robust variance estimator to account for the clustering within matched pair.