We searched MEDLINE, EMBASE, ClinicalTrials.gov, and the Cochrane Central Register of Controlled Trials for English-language studies published from 2000 to May 1, 2017. 
MEDLINE
We searched MEDLINE, EMBASE, ClinicalTrials.gov, and the Cochrane Central Register of Controlled Trials for English-language studies published from 2000 to May 1, 2017. 
EMBASE
We searched MEDLINE, EMBASE, ClinicalTrials.gov, and the Cochrane Central Register of Controlled Trials for English-language studies published from 2000 to May 1, 2017. 
ClinicalTrials.gov
We searched MEDLINE, EMBASE, ClinicalTrials.gov, and the Cochrane Central Register of Controlled Trials for English-language studies published from 2000 to May 1, 2017. 
Cochrane Central Register of Controlled Trials