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. 2020 Sep 18;10(9):e041537. doi: 10.1136/bmjopen-2020-041537

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© Author(s) (or their employer(s)) 2020. Re-use permitted under CC BY. Published by BMJ.

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Flow chart of search results and selection procedure. BMJ, British Medical Journal; JAMA, Journal of the American Medical Association; NEJM, New England Journal of Medicine.