Table 2.

Results of subgroup analysis

Subgroup	No of studies	Random-effects model		Fixed-effects model		Heterogeneity
		HR (95% CI)	P-value	HR (95% CI)	P-value	I2 (%)	P-value
Predominant treatment
Surgery	10	1.46 (1.26–1.68)	<0.01	1.41 (1.26–1.58)	<0.01	27.3	0.19
Chemotherapy	3	1.78 (1.48–2.13)	<0.01	1.78 (1.48–2.13)	<0.01	0.0	0.70
Country
Japan	6	1.66 (1.29–2.14)	<0.01	1.57 (1.28–1.93)	<0.01	23.4	0.26
Other	7	1.51 (1.30–1.77)	<0.01	1.49 (1.33–1.66)	<0.01	44.5	0.09
Sample size
<300	6	1.73 (1.35–2.20)	<0.01	1.60 (1.34–1.92)	<0.01	28.7	0.22
≥300	7	1.48 (1.27–1.73)	<0.01	1.47 (1.31–1.65)	<0.01	39.5	0.13
NOS score
<7	5	1.65 (1.41–1.92)	<0.01	1.64 (1.42–1.88)	<0.01	16.2	0.31
≥7	8	1.46 (1.22–1.74)	<0.01	1.39 (1.22–1.59)	<0.01	30.6	0.18

Abbreviations: HR, hazard ratio; CI, confidence interval; NOS, Newcastle–Ottawa Quality Assessment Scale.