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.