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. 2014 Oct 9;11:144. doi: 10.1186/1743-0003-11-144

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© Noorkõiv et al.; licensee BioMed Central Ltd. 2014

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. 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.

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Flow of information through the different search phases of a systematic review based on PRISMA 2009 guidelines. Four search engines (i.e. MEDLINE, Scopus, IEEExplore and Compendex) were used to identify the relevant literature. After the screening based on title and abstract and removal of duplicates, 18 articles were selected. After the selection based on the full text article, 8 final articles were included in the current review.