Table 2.

Results of quality assessment

Ref.	Random sequence generation	Allocation concealment	Blinding of participants and personnel	Blinding of outcome assessment	Incomplete outcome data	Selective reporting	Other bias
Zhan, 2013[15]	Unclear	Unclear	High risk of bias	Unclear	Low risk of bias	Unclear	Unclear
Bai, 2008[16]	Unclear	Unclear	High risk of bias	Unclear	Low risk of bias	Unclear	Unclear
Wang, 2006[17]	Unclear	Unclear	High risk of bias	Unclear	Low risk of bias	Unclear	Unclear
Li, 2014[18]	Unclear	Unclear	High risk of bias	Unclear	Low risk of bias	Unclear	Unclear
Kochar, 2001[19]	Unclear	Unclear	High risk of bias	Unclear	Low risk of bias	Unclear	Unclear
Guan, 2017[20]	Unclear	Unclear	High risk of bias	Unclear	Low risk of bias	Unclear	Unclear
Zhao, 2015[21]	Unclear	Unclear	High risk of bias	Unclear	Low risk of bias	Unclear	Unclear
Chen, 2016[22]	Unclear	Unclear	High risk of bias	Unclear	High risk of bias	Unclear	Unclear