Table 3.

Qualitative risk of bias assessment summary.

Study	Sequence generation	Allocation concealment	Blinding of personnel and participants	Blinding of outcomes	Incomplete outcome data addressed	Free of selective reporting	Free of other biases
Choi et al., 2014 [21]	Yes	Unclear	Yes	Yes	Yes	Yes	Yes
Chen, 2012 [20]	No	Unclear	Yes	Yes	Yes	Unclear	Yes
Cui et al., 2012 [31]	Yes	Unclear	Unclear	Unclear	Yes	Yes	Yes
Inoue et al., 2012 [26]	Unclear	Unclear	Unclear	Unclear	Yes	Yes	Unclear
Liu et al., 2010 [29]	Yes	Unclear	Yes	Yes	Unclear	Yes	Yes
Lu et al., 2008 [24]	Unclear	Unclear	Yes	Yes	Unclear	Yes	Yes
Tsimoyiannis et al., 2002 [28]	Unclear	Unclear	Unclear	Unclear	Yes	Yes	Yes
Wang et al., 2010 [30]	Unclear	Unclear	Yes	Yes	Unclear	Yes	Yes
Wilhelm et al., 2011 [23]	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Xu et al., 2010 [32]	Unclear	Unclear	Yes	Yes	Yes	Yes	Yes

Yes: low risk of bias; No: high risk of bias.