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. 2018 Oct 30;16:196. doi: 10.1186/s12916-018-1180-x

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© The Author(s). 2018

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 diagram. Diagram illustrating the literature selection process, including identification, screening, eligibility, and total studies included in the global analysis and clinical characteristic analysis. Reasons for exclusion of full texts are detailed. Individual-level details of each study reviewed are found in Additional file 2