Table 2.

Quality assessment of included randomized controlled trials.

Included trials	Random sequence generation	Allocation concealment	Blinding of participants and personnel	Blinding of outcome assessment	Incomplete outcome data	Selective reporting	Other sources of bias	Risk of bias
Liu et al., 2009 [30]	Unclear	Unclear	Unclear	Unclear	Yes	No	Unclear	High
Chen et al., 2006 [31]	Unclear	Unclear	Unclear	Unclear	Yes	No	Unclear	High
Ji and Han, 2011 [32]	Unclear	Unclear	Unclear	Unclear	Yes	No	Unclear	High
Yuan, 2006 [33]	Unclear	Unclear	Unclear	Unclear	Yes	No	Unclear	High
Shi, 2011 [34]	Unclear	Unclear	Unclear	Unclear	Yes	Yes	Unclear	High
Li and Wan, 2006 [35]	Unclear	Unclear	Unclear	Unclear	Yes	No	Unclear	High
Liang, 2011 [36]	Unclear	Unclear	Unclear	Unclear	Yes	No	Unclear	High
Fu and Xiao, 2011 [37]	Table of random number	Unclear	Unclear	Unclear	Yes	Yes	Unclear	Unclear
Yang et al., 2008 [38]	Unclear	Unclear	Unclear	Unclear	Yes	No	Unclear	High
Lin and Zhou, 2004 [39]	Unclear	Unclear	Unclear	Unclear	Yes	Yes	Unclear	High
Ai, 2012 [40]	Unclear	Unclear	Unclear	Unclear	Yes	Yes	Unclear	High
Qin, 2008 [41]	Unclear	Unclear	Unclear	Unclear	Yes	No	Unclear	High