Table 2.

Risk of bias analysis

	Random sequence generation	Allocation concealment	Blinding of participants and personnel	Blinding of outcome assessment	Incomplete outcome data	Selective reporting	Other bias
Alvaro‐Garcia et al. 2016 [61]
Castillo‐Cardiel et al. 2015 [49]
Chang et al. 2013 [20]
Garcia‐Olmo et al. 2009 [41]
Gentile et al. 2012 [23]
Gentile et al. 2014 [22]
Guadalajara et al. 2012 [42]
Han et al. 2009 [66]
Henry et al. 2016 [76]
Herreros et al. 2012 [43]
Houtgraaf et al. 2012 [74]
Koh et al. 2012 [54]
Koh et al. 2012 [34]
Koh et al. 2014 [51]
Koh et al. 2016 [52]
Kølle et al. 2013 [24]
Li et al. 2013 [25]
Marino et al. 2013 [67]
Onesti et al. 2016 [60]
Panés et al. 2016 [44]
Peltoniemi et al. 2013[28]
Perin et al. 2014 [75]
Sterodimas et al. 2011 [29]
Tanikawa et al. 2013 [30]
Tissiani et al. 2016 [61]
Vanikar et al. 2014 [82]
Zheng et al. 2014 [84]
	Low risk			Unclear		High risk
Color codes

All studies with a control group were included for the analysis. Green: Low risk of bias, Yellow: Unclear risk of bias, Red: High risk of bias.