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. 2018 Sep 19;4(1):e000430. doi: 10.1136/bmjsem-2018-000430

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© Author(s) (or their employer(s)) 2018. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.

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Preferred Reporting Items for Systematic Reviews and Meta-Analyses flow chart for selected trials included for the systematic review.