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. 2017 Dec 16;27(4):308–320. doi: 10.1136/bmjqs-2017-007087

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PRISMA flow diagram of selection of eligible studies. NICE, National Institute for Health and Care Excellence; PRISMA, Preferred Reporting Items for Systematic Reviews and Meta-Analyses; AMED, Allied and Complementary Medicine Database; ERIC, Education Resources Information Center; CINAHL, Cumulative Index to Nursing and Allied Health Literature.