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Systematic Reviews: Protocol

Overview of systematic review methodology and key strategies for searching and reporting to the Cochrane Collaboration's Gold Standard

Heading: Protocol

Protocol overview

Once you have defined your question, you need to develop a systematic review protocol.  The purpose of a protocol is to outline your systematic review process in a clear and transparent manner to reviewers and readers.

The content in a protocol includes:

  • Research questions and aims of the review.
  • Your PICO breakdown (or the relevant framework you are using).
  • Your eligibility criteria (inclusion and exclusion).
  • Where you will search (databases and grey literature).
  • How you will:
    • screen your records
    • extract and manage the data
    • assess bias
    • analyse data

Your eligibility criteria is what you plan to include and exclude from your review. It needs to:

  • match each of your PICO elements
  • be agreed upon by all reviewers before screening starts

The key areas for your criteria are:

Demographic factors

e.g. age, sex, ethnicity

Study design and duration

e.g. what types of studies do you need to answer your question?

Measure

e.g. are you looking at a particular type of measure?

Date range

e.g. only apply a date range if you are updating a previously published systematic review

Watch the following video by Dr Saravana Kumar, Associate Professor in Physiotherapy, UniSA.

Video Length: 4:46

  • Eligibility criteria helps reviewers determine what to include/exclude in a systematic review.
  • The eligibility criteria should address:
    • the details of your PICO element.
    • research design and study types (Note: different review questions requires different study design).
    • language of the publication.
  • Always justify your eligibility (inclusion/exclusion) criteria in your systematic review paper.
PRISMA for systematic review protocol (PRISMA-P)

PRISMA-P is 'a guideline to help authors prepare protocols for planned systematic reviews and meta-analyses that provides them with a minimum set of items to be included in the protocol.' - PRISMA-P Statement, p. 2

Publisher requirement

While PRISMA-P is the preferred reporting items for systematic reviews and meta-analysis, there may be other specific requirements from your review body or publisher, for example:

  • breakdown of number identified through databases searches.
  • breakdown of number of records excluded through:
    • title screening
    • abstract screening
    • full-text screening 

To view criteria descriptions, hover the cursor over the green arrow, or download the file below.

The hierarchy of evidence

Many tables have been developed to show you the different levels of evidence.

The image below represents the hierarchy of evidence adapted from the National Health and Medical Research Council (NHMRC)

Level of evidence hierarchy. At the bottom of the pyramid, the volume of studies is high but the level of evidence is low. As you move up the pyramid the number of studies decreases but the quality increases.

Guidelines and standards

'Provide registration information for the review, including register name and registration number, or state that the review was not registered.'

'Indicate where the review protocol can be accessed, or state that a protocol was not prepared.'

'Describe and explain any amendments to information provided at registration or in the protocol.' 

- PRISMA 2020 Explanation and Elaboration, p. 28


Other standards

Make your protocol visible

Registering your protocol

It is a good practice to register your protocol, as you do not want anyone else to do the exact same review you are doing.

A good place to register a health review is PROSPERO. Once you register, your review will:

  • be available open access through the PROSPERO database.
  • have a unique registration number. This number can be cited in publications and reports to provide the link between your planned and completed review. This is recommended by PRISMA (2009) and many publishers.
Publishing your protocol

You can publish your protocol in the following journals and databases:

Protocols for Cochrane and Joanna Briggs Institute reviews are published on their websites:

Many other journals will allow you to publish your protocol. You should also look for relevant journals within your discipline area.

Further resources