Table 2.

Risk of bias in include studies

The first author	Publication year	Adequate sequence generation	Allocation concealment	Blinding (Participant)	Blinding (Personnel)	Blinding (Outcome assessor)	Incomplete outcome data (attrition bias)	Selective reporting (reporting bias)	Other bias
Chen XL	2009	Unclear	Unclear	Unclear	Unclear	Unclear	Low risk	Low risk	Low risk
Cheng AB	2010	Unclear	Unclear	Unclear	Unclear	Unclear	Unclear	Low risk	Low risk
Gui CM	2012	High risk	High risk	Unclear	Unclear	Unclear	Low risk	Low risk	Low risk
Hu XY	2007	Unclear	Unclear	Unclear	Unclear	Unclear	Unclear	Low risk	Low risk
Gong ZH	2011	Low risk	Unclear	Unclear	Unclear	Unclear	Low risk	Low risk	Low risk
Chen J	2007	Unclear	Unclear	Unclear	Unclear	Unclear	Low risk	Low risk	Low risk
Fan JB	2014	Unclear	Unclear	Unclear	Unclear	Unclear	Unclear	Low risk	Low risk
Lei S	2005	Unclear	Unclear	Unclear	Unclear	Unclear	Unclear	Low risk	Low risk
Li YN	2009	Unclear	Unclear	Unclear	Unclear	Unclear	Low risk	Low risk	Low risk
Wu JN	2004	Low risk	Low risk	Unclear	Unclear	Unclear	Unclear	Low risk	Low risk
Wu JF	2013	Low risk	Low risk	Low risk	Low risk	Low risk	Low risk	Low risk	Low risk
Wu JF	2014	Low risk	Low risk	Low risk	Low risk	Low risk	Low risk	Low risk	Low risk
Zhang BJ	2014	Unclear	Unclear	Unclear	Unclear	Unclear	Low risk	Low risk	Low risk
Zhang Z	2006	Unclear	Unclear	Unclear	Unclear	Unclear	Unclear	Low risk	Low risk
Zhou LX	2009	Unclear	Unclear	Unclear	Unclear	Unclear	Low risk	Low risk	Low risk
Zhao MY	2007	Low risk	Low risk	Unclear	Unclear	Unclear	Low risk	Low risk	Low risk
Zhou Q	2011	Low risk	Low risk	Unclear	Unclear	Unclear	Low risk	Low risk	Low risk
Zhu SJ	2015	Unclear	Unclear	Unclear	Unclear	Unclear	Low risk	Low risk	Low risk
Lu FP	2015	Unclear	Unclear	Unclear	Unclear	Unclear	Low risk	Low risk	Low risk