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/exclusion 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 at a later date, 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:
Protocols can be used as in-house documentation or can be registered to increase visibility of what you're undertaking (see below). 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.