Table 2.

Risk of bias and quality of evidence 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 assessor	incomplete outcome data	selective reporting
Prehn et al. [22]	Low	Low	Low	Low	Low	Low	Low
Kim et al. [17]	Low	Low	Low	High	Low	Low	Low
Horie et al. [20]	Low	Low	Low	Low	Low	Low	Low
Martin et al. [18]	Low	Low	Low	Unclear	Low	Low	Low
Cheatham et al. [23]	Low	Low	Low	Low	Low	Low	Low
Peven et al. [16]	Low	Low	Low	High	High	Low	Low
Espeland et al. [15]	Low	Low	Low	Low	Low	Low	Low
Smith et al. [21]	Low	Low	Low	Low	Low	Low	Low
Trevizol et al. [19]	Low	Low	Low	Unclear	Low	Low	Low