Table 3. Subgroup analyses for the treatment effect on overall survival of neoadjuvant chemotherapy followed by concurrent chemoradiotherapy versus concurrent chemoradiotherapy with or without adjuvant chemotherapy for locoregionally advanced nasopharyngeal carcinoma.

Factors	Subgroups	Availability		Effect		Heterogeneity		Interaction
		Trials (N)	Patients (N)	HR (95% CI)	P value	I2	P value	P value
Duration of follow-up
	<48 months	4	1327	0.62(0.47-0.84)	0.002	0.0	0.927	0.960
	>48 months	3	378	0.60(0.19-1.87)	0.380	59.6	0.084
Radiotherapy techniquea
	Conventional radiotherapy	3	377	0.59(0.38-0.92)	0.021	32.7	0.226	0.285
	IMRT/3DCRT	4	1328	0.67(0.49-0.93)	0.015	0.0	0.492
Sample size
	<150 patients	3	318	0.62(0.29-1.32)	0.216	59.0	0.087	0.999
	>150 patients	4	1387	0.62(0.45-0.85)	0.003	0.0	0.912
CCRT timingb
	q1wk	4	490	0.65(0.34-1.25)	0.198	39.5	0.175	0.872
	q3wk	3	1215	0.61(0.45-0.84)	0.003	0.0	0.826
Method of data extractionc
	Directly reported	4	1180	0.61(0.44-0.85)	0.003	0.0	0.999	0.755
	Indirect method	3	525	0.70(0.45-1.09)	0.112	44.1	0.147
IC regimen
	Two drugs	5	1392	0.59(0.44-0.78)	0.000	0.0	0.543	0.119
	Three drugs	2	313	1.05(0.54-2.04)	0.885	0.0	1.000
	Taxol-included	3	378	0.60(0.20-1.87)	0.380	59.6	0.084	0.962
	Non-taxol-included	4	1327	0.62(0.47-0.84)	0.002	0.0	0.927
AC
	With	1	802	0.64(0.49-0.83)	0.005	-	-	0.798
	Without	6	903	0.70(0.50-0.98)	0.040	0.0	0.420
Data source
	Published	6	1492	0.64(0.48-0.87)	0.004	10.2	0.351	0.913
	Unpublished	1	213	0.69(0.25-1.93)	0.883	-	-

^aRadiotherapy technique was classified as conventional radiotherapy or IMRT/3D-CRT based on the radiotherapy applied for at least 70% of the study population.

^bHR and its 95% CI were directly reported or indirectly calculated according to the method by Parmar et al. [46] in a trial.

^cIncluding one trial in which chemotherapy was administered every 4 weeks[20].

See Table 2 for abbreviations.