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Systematic Reviews

An introductory guide to Systematic Reviews

PRISMA Reporting Guidelines

To be systematic implies a focus on structure, organization and documentation. As in all research, the review process should be transparently documented in all parts, reported clearly in the final publication, and reproducible.

To address the issue of suboptimal reporting of meta-analyses, an international group developed a guidance called the QUOROM statement (QUality Of Reporting Of Meta-analyses) that focused on the reporting of meta-analyses of randomized controlled trials. In 2009, the QUOROM was updated to the PRISMA statement. 

The PRISMA Statement, PRISMA being an acronym for Preferred Reporting Items for Systematic Reviews and Meta-Analyses, is an evidence-based minimum set of items for reporting in systematic reviews and meta-analyses. PRISMA focuses on the reporting of reviews evaluating randomized trials, but can also be used as a basis for reporting systematic reviews of other types of research, particularly evaluations of interventions.

It consists of a 27-item checklist (a list of information to be provided when reporting a systematic review or meta-analysis) and a four-phase flow diagram (PRISMA flow diagram) for depicting the flow of information through the systematic review process. The checklist includes items deemed essentials for transparent reporting of a systematic review.

In the PRISMA 2020 checklist, two items concern reporting of the searching methods used:

  • Item 6: Information sources – Describe all information sources (e.g., databases with dates of coverage, contact with study authors to identify additional studies) in the search and date last searched. Other information you can include are, search terms used (potentially alongside their justifications) or if multiple authors are responsible for assessing studies for inclusion in your paper, include how these decisions were made, or conflicts resolved.
  • Item 7: Search Strategy – Present full search strategies for all databases, including any filters and limits used, such that it could be repeated. The majority of journals allow you to upload supplemental material.

Jewell, S. (2017). Assembling the pieces of a systematic review - a guide for librarians. Rowman & Littlefield. and Jewell.
(2021). PRISMA. :

PRISMA flow diagram

The PRISMA flow diagram is a method that can be used to document the study selection process in context of the entire systematic review, within the following four key areas:

  • Identification
  • Screening
  • Eligibility
  • Included

The flow diagram depicts the flow of information through the different phases of a systematic review. It maps out the number of records identified, included and excluded, and the reasons for exclusions. These diagrams are an important part of the process of reporting reviews as they enable readers to see how the review authors accounted for all the references retrieved in their review.

(2021). PRISMA. : .

Further reading:

PRISMA website. [Transparent Reporting of Systematic Reviews and Meta-Analyses]. Accessed March 2022.