Table 2.

Quality of the included studies.

Studies	Random sequence generation	Allocation concealment	Blinding	Incomplete outcome data	Selective reporting	Other bias
Holenarasipur et al. 2003	High risk	Unclear	Unclear	Low risk	Low risk	Low risk
Kim et al. 2010	High risk	High risk	Unclear	Low risk	Low risk	Low risk
Wang et al. 2014	High risk	Unclear	Unclear	Low risk	Low risk	Low risk
Kang et al. 2012	Low risk	Unclear	Unclear	Low risk	Low risk	Low risk
Shunsuke et al. 2011	High risk	Unclear	Unclear	Low risk	Low risk	Low risk
Tahaniyat et al. 2010	High risk	Unclear	Unclear	Low risk	Low risk	Low risk
Christopher et al. 2005	Unclear	Unclear	Unclear	Low risk	Low risk	Low risk
Sendhil et al. 2005	Unclear	Unclear	Unclear	Low risk	Low risk	Low risk
Bruno et al. 2004	Unclear	Unclear	Unclear	Low risk	Low risk	Low risk
Yasuhiro et al. 1991	Unclear	Unclear	Unclear	Low risk	Low risk	Low risk