Table 2.

Risk of bias within included studies

	Study	Selection bias		Performance bias	Detection bias	Attrition bias	Reporting bias	Other bias	Overall bias
		Random sequence generation	Allocation concealment	Participant and personnel blinding	Outcome assessor blinding	Incomplete outcome data	Selective outcome reporting
Group research designs
Level II and III studies	Bar-Haim et al27	Low	Low	High	Low	High	Low	High	Low
	Bleyenheuft et al25	Low	Low	High	Unclear	High	Unclear	Unclear	Unclear
	Declerck et al26	Low	Low	High	Unclear	Unclear	Low	High	Unclear
	Grecco et al28	Low	Low	High	Low	Unclear	Low	Unclear	Low
	Ketelaar et al33	Low	Unclear	High	Low	Unclear	Unclear	Unclear	Unclear
	Kumban et al33	Low	Low	High	Low	High	Low	Unclear	Low
	Swe et al30	Low	Low	High	Low	Low	Low	Unclear	Low
	Capio et al31	High	High	High	Unclear	Unclear	Unclear	Unclear	Unclear
	Hemayattalab et al32	High	Unclear	High	Unclear	Unclear	Unclear	Unclear	Unclear
	Hemayattalab and Rostami34	Unclear	High	High	Unclear	Low	Low	Unclear	Unclear
	Löwing et al35	High	High	High	High	Low	Low	High	High
IV	Sorsdahl et al36	High	High	High	Low	High	Low	Unclear	High
Single-subject design
I	Thorpe and Valvano14	Low	Unclear	High	High	Low	Low	Unclear	Unclear