A systematic search was conducted in MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials. 
MEDLINE
A systematic search was conducted in MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials. 
EMBASE
A systematic search was conducted in MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials. 
Cochrane Central Register of Controlled Trials