 Systematic reviews and meta-analyses are important tools used to summarize research findings on the effectiveness and safety of healthcare interventions. However, the quality of reporting of such studies can be improved by following the preferred reporting items for systematic reviews and meta-analyses, Prisma, Statement. This statement provides a checklist of 27 items and a four-phase flow diagram to help authors report systematic reviews and meta-analyses clearly and transparently. This article was authored by Alessandro Liberati, Douglas G. Altman, Jennifer Tetzlaff, and others.