A search strategy used Medline, Embase, Cochrane databases, and proceedings of international meetings. 
Medline
A search strategy used Medline, Embase, Cochrane databases, and proceedings of international meetings. 
Embase
A search strategy used Medline, Embase, Cochrane databases, and proceedings of international meetings. 
Cochrane databases
A search strategy used Medline, Embase, Cochrane databases, and proceedings of international meetings. 
proceedings of international meetings