Table 3.

Assessment of risk of bias in the included studies

First author, reference, (year)	Selection bias		Performance bias	Detection bias	Attrition bias	Reporting bias	Other bias
	Random sequence generation	Allocation concealment	Blinding of participants and personnel	Blinding of outcome assessment	Incomplete outcome data addressed	Free of Selective outcome reporting	Free of Other sources of bias
Huang et al., 2005	Unclear	Unclear	Yes	Yes	Unclear	Unclear	Unclear
Zhao et al., 2009	Unclear	Unclear	Unclear	Unclear	Unclear	Unclear	Unclear
Li et al., 2010	Yes	Unclear	Unclear	Unclear	Unclear	Unclear	Unclear
Xu J, 2010	Unclear	Unclear	Unclear	Unclear	Unclear	Unclear	Unclear
Xu XH, 2010	Yes	Unclear	Unclear	Unclear	No	Unclear	Unclear
Zhang et al., 2011	Unclear	Unclear	Unclear	Unclear	No	Unclear	Unclear
Liao et al., 2011	Yes	Unclear	Yes	Yes	Unclear	Yes	Unclear
Liu et al., 2012	Unclear	Unclear	Unclear	Unclear	Unclear	Unclear	Unclear
Wang et al., 2012	Unclear	Unclear	Unclear	Unclear	Unclear	Yes	Unclear

Yes, low risk of bias; No, high risk of bias; Unclear, uncertain risk of bias.