Systematic review protocols describe the rationale, hypothesis, and planned methods of the review. It should be prepared before a review is started and used as a guide to carry out the review. Reporting the planned methods ahead of conducting the review allows the review process to be transparent, and helps reduce bias in the final product of the review.
Detailed protocols should be developed a priori, made publicly available, and registered in a registry, such as PROSPERO, or published in a journal like Systematic Reviews.
For more on systematic review protocols, take a look at this post from BioMedCentral, co-written by one of the founding Editors-in-Chief of Systematic Reviews.
PRISMA (Preferred Reporting items for Systematic Reviews and Meta-Analyses) protocols are one of the most common protocol types for systematic reviews. The website provides a protocol checklist (to help you write your protocol), extensions to the protocols (for additional details), and documentation that helps explain each aspect of the protocol.
Cochrane Systematic Reviews follow the procedures outlined in the Cochrane Review handbook. Further, Cochrane has explicit methodological standards that all Cochrane protocols, reviews, and updates are expected to adhere- see more at Methodological Expectations of Cochrane Intervention Reviews.
MOOSE stands for Meta-Analysis of Observational Studies in Epidemiology, and the reporting guidelines are made to specifically focus on observational studies and the statistical analysis of their results. For more information, take a look at the original paper: Meta-analysis of Observational Studies in Epidemiology: A Proposal for Reporting by Stroup, Berlin, Morton, et al.
