Original citation: Moher D, Liberati A, Tetzlaff J, Altman DG, The PRISMA Group. Preferred Reporting Items for Systematic Reviews and Meta-Analyses: The PRISMA Statement. PLoS Med. 2009;6:e1000097. The original authors have not revised and verified the Spanish translation, and not necessary endorse it. Los autores originales no han revisado ni verificado la traducción del manuscrito al español, y no necesariamente están de acuerdo con su contenido. Original article published: July 21, 2009 Copyright: © 2009 Moher et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Provenance: Not commissioned; externally peer reviewed. In order to encourage dissemination of the PRISMA Statement, this article is freely accessible on the PLoS Medicine Web site (http://medicine.plosjournals.org/) and will be also published in the Annals of Internal Medicine, BMJ, Journal of Clinical Epidemiology, and Open Medicine. The authors jointly hold the copyright of this article. For details on further use, see the PRISMA Web site (http://www.prisma-statement.org/). Spanish translation: Mercedes Sotos-Prieto, Johana Prieto, Maria Manera, Eduard Baladia, Rodrigo Martínez-Rodríguez y Julio Basulto. Corresponding author of the spanish translation: Mercedes Sotos-Prieto (merchesotosprieto@gmail.com)