Table 2.

Assessment of the methodological quality of each included study

	1. Sample representative for the target population?	2. Sample included in the study in a valid and reliable way?	3. Adequate explanation whether the respondents differed from non-responders?	4. Is there an acceptable response rate (70% or above)?	5. Are measurements appropriate?	6. Is data collection standardized?	7. Is data analysis standardized?	8. Are the results relevant for clinical practice?	9. Are the results in line with other available studies?
Surveysa
AL-Qudimat, MR, 2011 [28]	+	+	–	+	+	+	+	+	+
Ball SD, 2005 [29]	+	+	?	?	–	+	+	+	+
Ben Arush, 2006 [30]	+	+	?	?	+	+	+	+	+
Fernandez C, 1998 [31]	+	+	+	+	+	+	+	+	+
Gagnon EM, 2003 [32]	+	+	?	?	+	+	+	+	+
Gozum S, 2007 [33]	+	+	?	–	+	+	+	+	+
Ladas EJ, 2014 [34]	+	+	+	+	+	+	+	+	+
Laengler A, 2008 [35]	+	+	?	–	+	+	+	+	+
Magi T, 2015 [18]	+	+	+	–	+	+	+	+	+
Molassiotis A, 2004 [36]	+	+	–	–	+	+	+	+	+
Ndao DH, 2013 [37]	+	+	–	?	+	+	+	+	+
Olbara G, 2018 [38]	+	+	+	+	+	+	+	+	+
Rajanandh MG, 2018 [39]	+	?	–	?	–	+	+	+	–
Singendonk M, 2013 [40]	+	+	+	+	+	+	+	+	+
Susilawati D, 2016 [41]	+	+	+	+	+	+	+	+	+
Turhan AB, 2016 [10]	+	+	?	+	+	+	+	+	+
	1. Is the source of the opinion clearly identified?	2. Does the source of the opinion have standing in the field of expertise?	3. Are the interests of the relevant population the central focus of the opinion?	4. Is the stated position the result of an analytical process?	5. Is there reference to the extant literature?	6. Is any incongruence with the literature/sources logically defended?
Expert opinionsb
Agapito J, 2000 [42]	+	+	+	+	+	+
The American Academy of  Paediatrics, 2001 [43]	+	+	+	+	+	+
Clayton MF, 2006 [44]	+	+	+	+	+	?
Gilmour J, 2011 [45]	+	+	+	+	+	+
Tautz C, 2005 [46]	+	+	+	+	+	+
	1. Was there a clear statement of the aims of the research?	2. Is a qualitative methodology appropriate?	3. Was the research design appropriate to address the aims of the research?	4. Was the recruitment strategy appropriate to the aims of the study?	5. Was the data collection in a way that addressed the research issue?	6. Is relationship between researcher and participants adequately considered?	7. Have ethical issues been taken into consideration?	8. Was the data analysis sufficiently rigorous?	9. Is there a clear statement of findings?	10. Is the research valuable?
Qualitative studiesc
Bold J, 2001 [47]	+	?	+	+	?	–	?	–	–	+
Fletcher PC, 2004 [48]	+	+	+	+	+	+	–	?	+	+
Krogstad T, 2007 [49]	+	+	+	+	+	–	–	–	+	–

(+) = Yes

(−) = No

(?) = Uncertain/Unable to assess

Assessed according to the following checklists: ^aThe Joanna Briggs Institute (2017): Critical Appraisal tools for use in JBI Systematic Reviews. Checklist for Analytical Cross Sectional Studies. ^bThe Joanna Briggs Institute (2017): Critical Appraisal tools for use in JBI Systematic Reviews. Checklist for Text and Opinion, and ^cCritical Appraisal Skills Programme (CASP) checklist for qualitative research (accessed 2019)