The review protocol sets out the methods to be used in the review and provides an explicit plan for your work. Decisions about the review question, inclusion criteria, search strategy, study selection, data extraction, quality assessment, data synthesis and plans for dissemination should be addressed. If modifications to the protocol are required, these should be clearly documented and justified. Modifications may arise from a clearer understanding of the review question, and should not be made because of an awareness of the results of individual studies.
Protocols help the systematic team stay on track and answering the original question, not something else. It also establishes a time-frame so it assists the team moving forward along the timeline.
The protocol should include:
- Search question or objective
- Inclusion/exclusion criteria (scope including types of studies, participants, interventions)
- Databases to be searched
- Proposed search strategy
- Methodology for data extraction and analysis
- Declaration of interests
- Time-frame
Protocols can be used as in-house documentation or can be registered to increase visibility of what you're undertaking. This may link you with other researchers with the same interests or alert others that your systematic review is in process and avoid duplication. You should also check to be sure someone else has not submitted a protocol similar to the one you're thinking of doing.
Consider registering your protocol. PROSPERO, from the Centre for Reviews and Dissemination at the University of York, is an international database of registered reviews in health and social care. Key features from registered reviews and recorded and maintained as a permanent record. Registration helps to promote transparency in the review process and also reduces the potential for duplication.