Table 2.

Cochrane risk of bias assessment.

Study	Year	Random sequence generation	Allocation concealment	Blinding of participants	Blinding of outcome assessment	Free of incomplete outcome	Free of selective reporting	Other bias
Chen et al.	2016	L	L	L	L	L	L	L
Suliburska et al.	2012	U	U	L	L	L	L	L
Mielgo-Ayuso et al.	2014	L	L	L	L	L	L	L
Hsu et al.	2008	L	L	L	L	L	L	L
Roberts et al.	2021	L	L	L	L	L	L	L
Hsu et al.	2011	L	L	U	U	L	L	L
K. Diepvens et al.	2006	U	U	U	U	L	L	L
Bajerska et al.	2015	U	U	U	U	L	L	U
Zhang et al.	2020	L	L	L	L	L	L	L
Bogdanski et al.	2012	L	U	U	U	L	L	L
Huang et al.	2018	L	L	L	L	L	L	U

L, low risk of bias; H, high risk of bias; U, unclear risk of bias.