Systematic Reviews and Meta Analysis

From the Cochrane Handbook:

“The protocol sets out the context in which the review is being conducted. It presents an opportunity to develop ideas that are foundational for the review.”

“Preparing a systematic review is complex and involves many judgements. To minimize the potential for bias in the review process, these judgements should be made as far as possible in ways that do not depend on the findings of the studies included in the review.”

“Publication of a protocol for a review that is written without knowledge of the available studies reduces the impact of review authors’ biases, promotes transparency of methods and processes, reduces the potential for duplication, allows peer review of the planned methods before they have been completed, and offers an opportunity for the review team to plan resources and logistics for undertaking the review itself.”

Lasserson TJ, Thomas J, Higgins JPT. Chapter 1: Starting a review. In: Higgins JPT, Thomas J, Chandler J, Cumpston M, Li T, Page MJ, Welch VA (editors). Cochrane Handbook for Systematic Reviews of Interventions version 6.4 (updated August 2023). Cochrane, 2023. Available from www.training.cochrane.org/handbook.

A protocol is your plan for carrying out your knowledge synthesis. It presents the rationale for carrying out the project and clearly states the aims of the work. The protocol describes the process for selecting research for inclusion, including the provision of explicit criteria for assessing reports for inclusion and for analyzing the included reports. Hence, it is an internal document that helps team members work together more smoothly. But it also is a hedge against bias by clearly stating the rules of the game before any work has begun. A protocol makes it more difficult to alter selection patterns based on perceived results. Beyond acting as a roadmap for your research, protocols, when registered or published in some way, allow others to see your research plan, establishing priority and reducing the risk of duplicate research.