Table 1. Baseline characteristics of nasopharyngeal carcinoma patients treated with intensity-modulated radiotherapy with or without concurrent chemotherapy.

	The original unmatched cohort						The propensity-matched cohort
	IMRT alone (N = 254)		IMRT+CC (N = 407)		P	Standardized difference	IMRT alone (N = 241)		IMRT+CC (N = 241)		P	Standardized difference
	No.	%	No.	%			No.	%	No.	%
Age					0.021	0.181					0.894	0.012
Mean	48.31		46.24				47.99		47.85
SD	12.30		10.49				12.22		10.31
Median	46.50		45.00				46.00		47.00
Sex					0.540	0.049					0.917	0.009
Male	189	74.4	294	72.2			179	74.3	180	74.7
Female	65	25.6	113	27.8			62	25.7	61	25.3
Histology*					0.501	0.055					0.611	0.046
II	8	3.1	17	4.2			7	2.9	9	3.7
III	246	96.9	390	95.8			234	97.1	232	96.3
VCA-IgA†					0.160						0.628
<80	69	27.2	89	21.9		0.123	61	25.3	59	24.5		0.019
80–320	94	37.0	145	35.6		0.029	90	37.3	82	34.0		0.069
≥320	91	35.8	173	42.5		0.137	90	37.3	100	41.5		0.085
EA-IgA†					0.107						0.592
<10	111	43.7	147	36.1		0.155	102	42.3	97	40.2		0.042
10–40	80	31.5	134	32.9		0.031	78	32.4	73	30.3		0.045
≥40	63	24.8	126	31.0		0.138	61	25.3	71	29.5		0.093
T-stage					< 0.001						0.701
T1	74	29.1	96	23.6		0.126	73	30.3	69	28.6		0.036
T2	140	55.1	186	45.7		0.189	128	53.1	125	51.9		0.025
T3	40	15.7	125	30.7		0.360	40	16.6	47	19.5		0.076
N-stage					0.503	0.053					0.296	0.095
N0	104	40.9	156	38.3			92	38.2	81	33.6
N1	150	59.1	251	61.7			149	61.8	160	66.4
Clinical stage					< 0.001	0.360					0.407	0.075
II	214	84.3	282	69.3			201	83.4	194	80.5
III	40	15.7	125	30.7			40	16.6	47	19.5

Abbreviations: IMRT = intensity-modulated radiotherapy, CC = concurrent chemotherapy, SD = standard deviation, VCA = viral capsid antigen, EA = early antigen, IgA = immunoglobulin A

^*Based on the criteria of WHO histological type (1991): II - Differentiated non-keratinising carcinoma, III - Undifferentiated non-keratinising carcinoma

^†In accordance with the criteria adopted in previous studies