Table 4.

Risk of bias assessment using the Cochrane risk of bias tool for RCTs included in the systematic review and meta-analysis.

Study	Random sequence generation	Allocation concealment	Blinding of participants and personnel	Blinding of outcome assessment	Incomplete outcome data	Selective reporting	Other bias
Kim 2019	High risk	High risk	Low risk	Low risk	Low risk	Low risk	Unclear risk
Zhao 2017	Unclear risk	Unclear risk	Low risk	Low risk	Low risk	Low risk	Unclear risk
Borjesson 2005	Unclear risk	Unclear risk	Low risk	Low risk	Low risk	Low risk	Unclear risk
Stukenborg 2001	Low risk	Low risk	Low risk	Low risk	Low risk	Low risk	Unclear risk
Weidenhielm 1992	Unclear risk	Unclear risk	Low risk	Low risk	Low risk	Low risk	Unclear risk
Jefferson 1989	High risk	High risk	Low risk	Low risk	Low risk	Low risk	Unclear risk