Figure 1

PRISMA-NMA diagram of the literature search. RCTs were identified from PubMed, CENTRAL and Clinicaltrial.gov databases and the searches were done in December 2016. The medical subject heading (MeSH) terms were used in the searching of PubMed and CENTRAL. In the searching of ClinicalTrials.gov, we limited the search for completed RCTs with results. There were 3840 references identified from the databases and a total 40 studies (35 full text publication and 5 unpublished studies) were included in the present study.