Table 3: AMSTAR scores for the methodological quality of included reviews and SIGN hierarchy of the level of evidence of included reviews.

		AMSTAR												SIGN
		1. Was an ‘a priori’ design provided?	2. Was there duplicate study selection and data extraction?	3. Was a compre-hensive literature search performed?	4. Was the status of publication (i.e. grey literature) used as an inclusion criterion?	5. Was a list of studies (included and excluded) provided?	6. Were the characteris-tics of the included studies provided?	7. Was the scientific quality of the included studies assessed and document-ed?	8. Was the scientific quality of the included studies used appropri-ately in formulating conclu-sions?	9. Were the methods used to combine the findings of studies appropri-ate?	10. Was the likelihood of publication bias assessed?	11. Was the conflict of interest included?
Smidt, et al., 2003, [11]	Yes		X	X				X	X	X	X	X	7	1++
	No	X				X	X
	Can't Answer
	Not applicable				X
Trudel, et al., 2004, [10]	Yes		X	X			X	X					4	1+
	No	X				X			X		X	X
	Can't Answer
	Not applicable				X					X
Bjordal, et al., 2008, [15]	Yes	X	X	X				X	X	X	X	X	8	1++
	No					X	X
	Can't Answer
	Not applicable				X
Sims, Miller and Elfar 2014, [16]	Yes		X	X			X					X	4	1−
	No	X				X		X	X
	Can't Answer
	Not applicable				X					X	X
Sayegh and Strauch, 2015, [18]	Yes			X			X	X	X	X	X	X	7	1+
	No	X	X		X	X
	Can't Answer
	Not applicable
Weber, et al., 2015, [17]	Yes		X	X	X				X	X	X	X	7	1+
	No	X				X	X	X
	Can't Answer
	Not applicable
Bisset, et al., 2015, [2]	Yes	X	X	X			X	X	X	X		X	8	1+
	No					X
	Can't Answer
	Not applicable				X						X