Table 2.

Risk of bias for included studies.

Study	Random sequence generation	Allocation concealment	Blinding of participants and personnel	Blinding of outcome assessment	Incomplete outcome data	Selective reporting	Other bias
Matsumoto 2005 (11)	Low risk	Low risk	Low risk	Low risk	Low risk	Low risk	Low risk
Matsumoto 2011 (12)	Low risk	Low risk	Low risk	Low risk	Low risk	Low risk	Unclear
Sakai 2015 (13)	Low risk	Unclear	High risk	Low risk	Low risk	Low risk	Unclear
Nakatoh (2017) (14)	Unclear	Low risk	High risk	High risk	Low risk	Low risk	Unclear
Jiang 2019 (15)	Low risk	Low risk	Low risk	Low risk	Low risk	Low risk	Unclear
Suzuki 2019 (16)	Low risk	Low risk	Unclear	Unclear	Low risk	Low risk	Low risk
Matsumoto 2020 (17)	Low risk	Unclear	High risk	Unclear	Low risk	Low risk	Low risk
Suzuki 2020 (18)	Unclear	Low risk	High risk	Low risk	Low risk	Low risk	Unclear