Table 1. The Cochrane risk of bias tool for quality assessment as it was implemented in the selected studies.

Study	Sequence generation	Allocation concealment	Blinding of participants, personnel and outcome assessors	Incomplete outcome data	Selective outcome reporting	Other sources of bias
Arent et al., 2010	?	+	+	?	?	+
Betts et al., 2009	?	?	?	+	+	?
Cockburn et al., 2013	?	?	?	+	+	?
Gentle et al., 2014	?	+	+	-	?	?
Gilson et al., 2010	+	+	-	+	?	+
Gunnarson et al., 2013	-	-	?	?	-	+
Highton et al., 2013	+	?	+	+	+	?
Naclerio et al., 2015	?	?	?	+	?	-
Naclerio et al., 2014	-	?	?	+	?	?
Poulios et al. 2018	?	?	+	+	+	?

+: Low risk of bias, - : High risk of bias, ? : unclear risk of bias.