What is a Protocol?
A protocol is a document that serves as a work plan for your review that describes the rationale, hypothesis, and planned methods of the review. Your protocol should be prepared before you start your review, even if things change along the way. Following a protocol allows for transparency, reproducibility, and minimizes biases. Many journals now require submitted systematic reviews to have registered protocols.
For systematic reviews, the PRISMA website provides several sources of guidance on writing a protocol.
For scoping reviews, the Joanna Briggs Institute provides guidance for writing a protocol in section 11.2 of their chapter on scoping reviews. Resources for scoping reviews can be found through the JBI Scoping Review Network.
In general, your protocol should have the following elements:
- Background literature review
- Review question
- Criteria for inclusion/exclusion of studies
- Types of studies, populations, interventions/exposures, outcome measures
- Search strategy for identification of studies
- Study selection methods
- Assessment of methodological quality (if applicable)
- Data extraction and synthesis
- Timeframe for conducting the review
(Adapted from: Booth, A., Sutton, A. and Papaioannou, D. (2016). Defining the scope. Systematic Approaches to a Successful Literature Review, 2nd edition.)
The protocol should include:
- the rationale for the review
- key questions broken into PICO (or other structured research question) components
- inclusion/exclusion criteria
- literature searches for published/unpublished literature
- data abstraction/data management
- assessment of methodological quality/risk of bias of individual studies (not required for scoping reviews)
- data synthesis
- grading the evidence for each key question
One of the most common mistakes researchers make when conducting a review is failure to develop a robust protocol in advance of beginning searches or abstract review
Registering or Publishing A Completed Protocol
Once you have written your protocol, consider registering it with an organization or publishing it in a journal. Listed below are a few example resources:
PROSPERO - Initiated in early 2011, this international database allows free registration of systematic reviews of interventions and strategies to prevent, diagnose, treat, and monitor health conditions in humans, for which there is a health-related outcome. At the present time, PROSPERO does not accept scoping review protocols.
More information and guidance on registering in PROSPERO can be found on their website.
- OSF Registries - Use the OSF (Open Science Framework) platform to preregister the protocol for your knowledge synthesis. This is a useful option if you are not publishing a systematic review or a review of interventions with health-related outcomes.
- BioMed Central Protocols - BioMed Central will consider protocols of any type of research for publication, following the standard peer review.
- BMJ Open - BMJ Open "will consider publishing without peer review protocols that have formal ethical approval and funding from a recognized, open access advocating research-funding body". Otherwise, protocols are peer reviewed.
- Systematic Reviews, a BioMed Central journal - This open access title publishes protocols of systematic reviews broadly related to health sciences.
Scoping reviews may not be registered with PROSPERO. Currently, they can be registered with the Open Science Framework or Figshare.
Publishing a Protocol
- BioMed Central Protocols
BioMed Central will consider protocols of any type of research for publication, following the standard peer review.
- BMJ Open
BMJ Open "will consider publishing without peer review protocols that have formal ethical approval and funding from a recognized, open access advocating research-funding body". Otherwise, protocols are peer reviewed.
- JBI Evidence Synthesis
Like systematic reviews, scoping review protocols can be published in some journals.
- Systematic Reviews, a BioMed Central journal
This open access title publishes protocols of systematic reviews broadly related to health sciences.