Figure 2.
The risk of bias of the included trials. (a) Risk of bias summary: each risk of bias item for each included study; (b) risk of bias graph: each risk of bias item is presented as percentages across all included studies.
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.