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Flow diagram for the search and inclusion criteria for studies in this review. Adapted from “Preferred Reporting Items for Systematic Reviews and Meta-Analyses: The PRISMA Statement,” by D. Moher, A. Liberati, J. Tetzlaff, D. G. Altman, and The PRISMA Group, 2009. PLoS Med 6(6). Copyright, 2009 by the Public Library of Science.
