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. 2016 May 6;13:57. doi: 10.1186/s12966-016-0380-z

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© Grieger et al. 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.

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Fig. 1 — PRISMA Flow chart of included studies. Flow chart indicates 3283 articles were retrieved (with removal of duplicates), followed by exclusion of 2803 articles based on irrelevant titles and exclusion of 378 abstracts. One hundred and two full text articles were examined in which 58 full text articles were excluded; leaving 44 studies included in the review