Table 2.

Results of sensitivity analysis.

Study excluded	HR (95% CI)	I 2	p
Yoshida et al. 2008	0.56 (0.45–0.70)	0.0%	0.695
Zhou et al. 2015	0.54 (0.41–0.70)	0.0%	0.733
Sohn et al. 2016	0.60 (0.48–0.74)	0.0%	0.802
Xu et al. 2014	0.58 (0.46–0.73)	0.0%	0.644
Zhu et al. 2015	0.56 (0.45–0.70)	0.0%	0.669
Toyoda et al. 2012	0.59 (0.47–0.73)	0.0%	0.775

HR: hazard ratio.