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

. 2018 Mar 15;18(3):873. doi: 10.3390/s18030873

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

© 2018 by the authors.

Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

PMC Copyright notice

Search strategy flow chart. After the removal of duplicates, 2040 papers were screened for inclusion: 183 were selected based on title and abstract, 119 full texts were further analysed. Three were included directly and 23 out of 95 were included after a consensus meeting. The references of the 209 papers obtained from the database search and those cited in the 23 reviews included in this paper were screened leading to the inclusion of further 77 papers for an overall total of 286 papers.