Table 1.

A structured search of key electronic bibliographic databases

Search type	Database	Database history	Filters applied
Systematic review of the literature	MEDLINE (via OVID 1946 to May 2017)	Biomedical database produced by the National Library of Medicine, with over 3000 journals	Limited to systematic reviews, narrative reviews, bibliometric reviews and meta-analysis
	EMBASE (1974 to May 2017)	Biomedical and pharmacological database, with a more European focus	Limited to systematic reviews, narrative reviews, bibliometric reviews and meta-analysis
	PsycINFO (1967 to May 2017)	Produced by the American Psychological Association covering over 1300 journals from Psychology and related disciplines	Limited to systematic reviews, narrative reviews, bibliometric reviews and meta-analysis