PRISMA flow diagram for peer-reviewed literature search and included studies. PRISMA flow diagram for peer-reviewed literature search and included studies. From Moher D, Liberati A, Tetzlaff J, et al. Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. PLoS Med 2009;6:e1000097. For more information, visit www.prisma-statement.org. Maha Bouzid et al. BMJ Glob Health 2018;3:e000648 © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.