Figure - PMC

Skip to main content

An official website of the United States government

Here's how you know

Here's how you know

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.

View full-text article in PMC

. 2019 Mar 26;2019(3):CD008521. doi: 10.1002/14651858.CD008521.pub4

Search in PMC
Search in PubMed
View in NLM Catalog
Add to search

Copyright © 2019 The Authors. Cochrane Database of Systematic Reviews published by John Wiley & Sons, Ltd. on behalf of The Cochrane Collaboration.

This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial License, which allows remixing, tweaking, and building upon the original work non-commercially, and although the new works must also acknowledge the original work and be non-commercial, derivative works don’t have to be licensed under the same terms.

PMC Copyright notice

Methodological quality summary: review authors' judgements about each methodological quality item for each included study.