Table 1. Assessment of risk of bias for 19 studies based on the Cochrane Handbook.

	Sequence Generation	Allocation Concealment	Blinding of Participants	Blinding of Personnel	Blinding of Outcome Assessment	Incomplete Outcome Data	Selective Outcome Reporting
Chen, 2009 [37]	U	U	U	U	U	U	L
Chen, 2012[36]	L	U	U	U	U	L	L
Cui, 2004 [38]	U	U	U	U	U	L	L
Guo, 2008 [39]	U	U	U	U	U	L	L
Hu, 2012 [40]	U	U	U	U	U	L	L
Huang, 2005 [41]	U	U	U	U	U	L	L
Jian, 2012 [42]	L	U	U	U	U	L	L
Li, 2012 [43]	L	L	H	H	L	L	H
Liao, 2011 [44]	L	U	U	U	U	L	L
Liu, 2009 [45]	U	U	U	U	U	L	L
Mao, 2009 [46]	L	U	U	U	U	U	L
Shan, 2011 [47]	U	U	U	U	U	L	L
Xu(2), 2012 [48]	U	U	U	U	U	L	L
Xu (1), 2012 [49]	U	U	U	U	U	U	L
Yu, 2011 [50]	U	U	U	U	U	U	L
Zhang (2), 2007 [51]	U	U	U	U	U	L	L
Zhang (1), 2007 [52]	U	U	U	U	U	L	L
Zhang, 2011 [53]	U	U	U	U	U	L	L
Zhao, 2012 [54]	U	U	U	U	H	L	L
Fan, 2012 [55]	U	U	U	U	U	L	L
Liang, 2013 [56]	U	U	U	U	U	L	H
Lin, 2013 [57]	U	U	U	U	U	L	H
Peng, 2013 [58]	L	U	U	U	U	L	L
Yang, 2013 [60]	U	U	U	U	U	L	L
Zeng, 2013 [59]	U	U	U	U	U	L	L

Risk of Bias Judgements: L: Low risk, U: Unclear risk, H: High risk.