- Publishing a protocol for a Cochrane Review establishes a public record of the review question and planned methods.
- Reporting clear definitions will help authors to adhere to a well formulated approach.
- Readers need to determine how far the review will address their own questions of interest.
- Changes to the review question or methods will need to be clearly described and justified in the full review.
Publishing the protocol for a Cochrane Systematic Review is a key milestone in the review process. As with any other form of research, it finalizes the development of the research question and sets out the different methods that will be used to address it.
Preparing and publishing a clearly conceived and well-written protocol serves a number of purposes. Investment of effort in the development of the review question and methods and the definition of the different aspects of the eligibility criteria will provide review authors with a clear plan to guide implementation of methods and reporting the full review, reducing their reliance on post hoc decisions. Publishing the protocol gives readers access to the plan from which the review will develop. It also helps them to judge how the eligibility criteria of the review, stated outcomes and planned methods will address the intended question of interest.
The protocol is a public record of the question of interest and the intended methods before results of the studies are fully known. This helps anyone who evaluates the review to judge how far it fulfills the original objectives. One of the key parts of the Cochrane Review prepublication screening programme involves the comparison between the intended methods with those implemented during the preparation of the review. It is crucial that review authors acknowledge and justify important differences between methods stated in the protocol and those used to produce the review findings. This is key to supporting replication, and provides users of the review with a sense of how far the review preserves the research question. Particularly important changes concern eligibility criteria, the definition or status of outcome measurements and methods relating to effect measures, data analysis and exploration of heterogeneity. Any changes that are made to these aspects of the review could potentially impact on the overall objectives as well as the interpretation of the evidence summarized by the review.
On publication Cochrane systematic review protocols are automatically assigned a record on PROSPERO, the register of ongoing and completed systematic reviews. For more information see www.crd.york.ac.uk/PROSPERO/.
Deputy Editor in Chief
Cochrane Editorial and Methods Department