Systematic Review Guide

What is a systematic review?

A systematic review is a type of literature review. Unlike other forms of review, where authors can include any articles they consider appropriate, a systematic review aims to remove the reviewer's bias as far as possible by following a clearly defined, transparent process. The Cochrane video below gives a clear summary.

Before starting, it’s really important that you ensure that your research question has not already been effectively answered in a recent review, and that no reviews on the topic are planned or already in progress.

Where can I find systematic reviews?

Some sources of published systematic reviews:

• Cochrane Library (In addition to Cochrane Reviews, the Cochrane Library provides access to major sources of systematic reviews: Epistemonikos, Social Systems Evidence, and Health Systems Evidence under the "More" tab).
• Campbell Collaboration
• Collaboration for Environmental Evidence (CEE)
• Best Evidence Medical and Health Professional Education Collaboration (BEME)

It is also possible to search for systematic reviews in many key databases.

Literature Searching Guide

Protocol Creation & Reporting 

Systematic reviews and other forms of evidence synthesis aim to minimise bias by using explicit methods that are outlined in advance in the form of a protocol. The protocol is a document that lays out the methodology of the review including: the review question; the context and rationale; the eligibility criteria; the search methods; selection and data extraction methods; appraisal and synthesis methods; and any other process that relates to the methodology of the review. 

Having the protocol created before the data collection begins is one way to minimise bias.

Sharing or publishing the protocol prior to the beginning of data collection improves transparency, increases accountability, and potentially reduces duplication of efforts by alerting others that this review is already planned and underway.

Reviews in progress (or prospective systematic reviews) may be referred to as protocols. A protocol clearly documents what the reviewers intend to do in their systematic review.

Some sources listing current protocols:

• Cochrane Library
• Joanna Briggs Institute (JBI) - systematic review register
• Best Evidence Medical and Health Professional Education Collaboration (BEME) - reviews in progress
• Prospero International Prospective Register of Systematic Reviews (Cochrane protocols are automatically uploaded to Prospero)

What is PRISMA?

Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) is an evidence-based minimum set of items for reporting in systematic reviews and meta-analyses.

The PRISMA 2020 statement has been published in a number of journals and can be viewed here

PRISMA resources include:

• PRISMA 2020 checklist - a checklist developed to improve the transparency of reporting. The checklist addresses the introduction, methods, results and discussion sections of a systematic review report.
• PRISMA 2020 Flow Diagram - 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. Different templates are available depending on the type of review (new or updated) and sources used to identify studies.
• PRISMA 2020 Flow Diagram generator - a tool that can be utilised to automate the flow diagram process
• PRISMA extensions - several extensions of the PRISMA Statement have been developed to facilitate the reporting of different types or aspects of systematic reviews. Examples include: PRISMA-S for searching, PRISMA-SCR for scoping reviews, PRISMA-P for protocols.

 Protocol templates and reporting guidelines:

Screening results

Screening process

​​​When reviewing the final search results from your chosen databases (and other sources if relevant), multiple reviewers (you and your supervisors or co-reviewers) will make decisions on which articles to include and exclude based on the criteria specified in your protocol. The first stage of this is usually based on titles and abstracts, then a full-text analysis follows before data extraction.

• Pre-screening:   Record the numbers of results from each database or source recorded before screening commences.
• Remove duplicates.
• Title/abstract screening:  Reviewers scan titles and abstracts to see if they match the criteria or have some value to the systematic review.  This may be done by a single reviewer, but done separately by multiple reviewers and the results compared, reduces the likelihood of bias.
• Full-text screening:  Multiple reviewers individually look through the full-text of included articles to fine-tune the final collection of articles that will contribute to the review.

You can Document your searches - using an Excel workbook (Monash University example template) or there is a range of tools that can be used to store citations and do the screening.

Assess the quality

There are a number of support resources to help you assess the quality of a piece of research:

• CONSORT http://www.consort-statement.org/ CONSORT stands for Consolidated Standards of Reporting Trials. It is an evidence-based, minimum set of recommendations for reporting randomized trials. It offers a standard way for authors to prepare reports of trial findings, facilitating their complete and transparent reporting, and aiding their critical appraisal and interpretation.
• Cochrane Handbook for Systematic Reviews of Interventions https://training.cochrane.org/handbook/current
• Joanna Briggs Institute has also developed a collection of Checklists that can be used to appraise studies. https://jbi.global/critical-appraisal-tools