A literature search was carried out using PubMed, Embase, Medline, Cochrane and Web of Science. 
PubMed
A literature search was carried out using PubMed, Embase, Medline, Cochrane and Web of Science. 
Embase
A literature search was carried out using PubMed, Embase, Medline, Cochrane and Web of Science. 
Medline
A literature search was carried out using PubMed, Embase, Medline, Cochrane and Web of Science. 
Cochrane
A literature search was carried out using PubMed, Embase, Medline, Cochrane and Web of Science. 
Web of Science