Table 2.

Assessment of the risk of bias

Auhtors	Borzoei et al. 2017 [25]	Borzoei et al. 2018 [10]	Wang et al. 2007 [26]	Wiweko and Susanto 2017 [27]	Salehpour et al. 2015 [28]	Kort et al. 2014 [29]	Hajimonfared nejad et al. 2017 [30]
Random sequence generation (selection bias)	L	L	L	L	L	L	L
Allocation concealment (selection bias)	L	L	L	L	L	L	L
Blinding of participants and personnel (performance bias)	L	L	L	L	L	L	L
Blinding of outcome assessment (detection bias)	L	M	U	L	L	U	U
Incomplete outcome data (attrition bias)	L	L	L	U	L	U	U
Selective reporting (reporting bias)	M	L	U	L	U	L	L
Other bias	L	L	L	U	U	L	U
Overall quality	L	L	L	L	L	L	L

L low risk of bias, M Moderate risk of bias, U Unknown