Fig. 2. Nine randomized controlled trials included in our meta-analysis. Quality of studies was assessed with the Cochrane Collaboration's tool. (A) Risk of bias summary. (B) Risk of bias graph.
Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.