Table 2.

Methodological quality assessment of the included studies

Authors	Selection bias		Performance Bias	Detection Bias	Attrition Bias	Reporting Bias	Other Bias	Overall Risk of Bias
	Random Sequence Generation	Allocation Concealment	Blinding of Participants & Personnel	Blinding of Outcome Assessment	Incomplete Outcome Data	Selective Outcome Reporting	Other Source of Bias	Overall Risk of Bias
Avci et al., 2002	No	No	Unclear	Unclear	Yes	Yes	Unclear	High Risk of Bias
Peters-Veluthamaningal et al., 2009	Yes	Yes	Yes	Yes	Unclear	Unclear	Unclear	Unclear Risk of Bias
Mehdinasab et al., 2010	No	No	No	No	Unclear	Yes	Unclear	High Risk of Bias
Hadianfard et al., 2013	Unclear	Unclear	No	No	No	Yes	Unclear	High Risk of Bias
Makarawung et al., 2013	Unclear	Unclear	Yes	Yes	Yes	Unclear	Unclear	Unclear Risk of Bias