Table 3.

Risk of bias summary. +: low risk of bias; ±: unclear risk of bias; −: high risk of bias.

	Random sequence generation	Allocation concealment	Blinding of participants and personnel	Blinding of outcome assessment	Incomplete outcome data	Selective reporting	Other bias
Alcantara et al.	+	+	±	−	+	+	+
Arezzo et al.	+	+	+	+	+	+	+
Cheung et al.	+	+	±	−	+	+	+
Ghazal et al.	+	+	±	−	+	+	+
Ho et al.	+	+	±	−	+	+	+
Pirlet et al.	+	+	±	−	+	+	+
van Hooft et al.	+	+	+	+	+	+	+