In order to encourage dissemination of the PRISMA explanatory paper, this article is freely accessible on the PLoS Medicine, Annals of Internal Medicine, and BMJ Web sites.

Provenance: Not commissioned externally peer reviewed. Navigate Left Previous article in issue.The PRISMA Statement, this document, and the associated Web site ( ) should be helpful resources to improve reporting of systematic reviews and meta-analyses. For each item, we include an example of good reporting and, where possible, references to relevant empirical studies and methodological literature. In this Explanation and Elaboration document, we explain the meaning and rationale for each checklist item. The checklist includes items deemed essential for transparent reporting of a systematic review.

The PRISMA Statement consists of a 27-item checklist and a four-phase flow diagram. Realizing these issues, an international group that included experienced authors and methodologists developed PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) as an evolution of the original QUOROM guideline for systematic reviews and meta-analyses of evaluations of health care interventions. Also, reviews of published systematic reviews have found that key information about these studies is often poorly reported. Since the development of the QUOROM ( QUality Of Reporting Of Meta-analysis) Statement-a reporting guideline published in 1999-there have been several conceptual, methodological, and practical advances regarding the conduct and reporting of systematic reviews and meta-analyses. Poor reporting of systematic reviews diminishes their value to clinicians, policy makers, and other users. The clarity and transparency of these reports, however, is not optimal. Systematic reviews and meta-analyses are essential to summarize evidence relating to efficacy and safety of health care interventions accurately and reliably.

Another word for previous studies