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

. 2016 Dec 1;16:246. doi: 10.1186/s12872-016-0425-x

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

© The Author(s). 2016

Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

PMC Copyright notice

Fig. 1 — Study selection flow diagram. Overview of process used to identify studies for inclusion in the systematic review. Three databases (MEDLINE, EMBASE, Cochrane) were searched for relevant articles. After identification, studies were screened against our inclusion criteria. Included studies were used in our meta-analysis