Table 1.

Quality assessment of the included studies

Study	Selection bias		Performance bias	Detection bias	Attrition bias	Reporting bias	Other bias
	Random sequence generation	Allocation concealment	Blinding of participants and personnel	Blinding of outcome assessment	Incomplete outcome bias	Selective reporting
Badawy [16]	U	U	H	L	U	L	H
Bagshaw [17]	L	L	L	L	H	L	H
Barbanti [18]	L	H	L	L	L	L	H
Bart [19]	U	U	H	L	H	H	H
Bart [20]	L	L	H	L	L	L	H
Berthelsen [21]	L	L	H	L	H	H	H
Briguori [22]	U	U	H	L	H	L	H
Cantarovich [8]	U	U	L	L	L	L	H
Costanzo [23]	U	U	H	L	U	H	H
Costanzo [24]	U	U	H	L	U	H	H
Costanzo [25]	L	L	H	L	H	H	H
Dussol [26]	L	L	H	L	U	H	H
Grams [27]	L	L	H	L	U	L	H
Hanna [28]	U	U	H	L	H	H	H
Lassnigg [7]	L	H	L	L	H	L	H
Lim [29]	L	U	L	L	H	H	H
Mahesh [30]	U	U	L	L	H	H	H
Marenzi [31]	L	U	L	L	H	H	H
Marenzi [32]	L	L	H	L	L	H	H
van der Voort [33]	U	U	L	L	L	H	H

H high, L low, U unknown