Table 2.

Results of subgroup meta-analysis and meta-regression analysis.

Subgroup	No. of studies	No. of patients	Random-effects model		Heterogeneity		Meta-regression P value
			HR (95% CI)	P value	Ph	I 2 (%)
Cancer type							0.860
NSCLC	3	320	2.50 (1.07–6.07)	0.035	<0.001	90
CRC	3	500	1.95 (1.34–2.84)	<0.001	0.735	0
GC	2	256	2.32 (1.48–3.64)	<0.001	0.636	0
Others	4	552	1.90 (1.00–3.61)	0.05	<0.001	83.3
Ethnicity							0.111
Asian	11	1283	2.35 (1.17–3.11)	<0.001	0.009	57.6
Caucasian	1	345	1.03 (0.90–1.17)	0.659
Sample size							0.066
≥100	9	1484	1.83 (1.33–2.50)	<0.001	<0.001	74.8
<100	3	144	3.60 (1.52–8.52)	0.004	0.012	77.6
Analysis method							0.772
Univariable	6	936	2.00 (1.23–3.25)	0.005	<0.001	81.8
Multivariable	6	692	2.32 (1.44–3.76)	0.001	0.001	76.7
Cut-off value							0.208
Median	9	1416	2.19 (1.39–3.45)	0.001	<0.001	88.9
Mean and others	3	212	1.91 (1.31–2.79)	0.001	0.464	0
Study design							0.924
Retrospective	10	1372	2.14 (1.41–3.26)	<0.001	<0.001	87.3
Prospective	2	256	2.32 (1.48–3.64)	<0.001	0.636	0

NSCLC, non-small-cell lung cancer; CRC, colorectal cancer; GC, gastric cancer; Ph, the P value of Q test for heterogeneity test.