There are four types of Cochrane reviews:

1. Intervention reviews assess the benefits and harms of interventions used in healthcare and health policy.
2. Diagnostic test accuracy reviews assess how well a diagnostic test performs in diagnosing and detecting a particular disease.
3. Overview of reviews.
4. Methodology reviews address issues relevant to how systematic reviews and clinical trials are conducted and reported.

For detailed information about the preparation of a Cochrane protocol or a review, peer reviewers of Cochrane Intervention protocols or reviews are referred to the Cochrane Handbook for Systematic Reviews of Interventions  and of Diagnostic Test Analysis protocols or reviews are referred to the Cochrane Handbook for Diagnostic Test Accuracy Reviews.

What is required of a peer reviewer?
Prior to publication, a protocol or a review (for short defined here as 'manuscript') is reviewed by at least one or more persons from each of the following groups: Cochrane review authors working in the area of interest, consumers or representatives of consumers acting as consumer peer reviewers, health-care professionals who are not Cochrane review authors, statisticians or methods expert, developing countries representatives. Peer reviewers should not have direct financial or personal conflicts of interest concerning the topic addressed. 

What is the process?
Peer reviewers are sent a copy of the protocol and a checklist for comments to be returned to the CHBG Managing Editor. We ask peer reviewers to submit courteous and constructive comments on the protocol that identify its weaknesses or fatal flaws, as well as ways of improving it. Peer reviewers are usually requested to return these comments within a specified in the letter time. 

Usually, one member of The CHBG Editorial Team is appointed Contact Editor of the manuscript. The Managing Editor, having collated the peer reviewer’s comments, forwards these to the Contact Editor and to the authors.

The revised and final version of the manuscript has to be approved by the Contact Editor or The Co-ordinating Editor or both prior to its publication on the Cochrane Library.

The CHBG's policy on commenting protocols and reviews
The peer reviewers’ process is ‘open’, ie, no attempt will be made to hide the identity of the peer reviewers from any one involved in the process as well as the general public. All feedback forms and other comments will be forwarded to the review authors. It is therefore important that no demeaning statements are included and that the comments raised are used to increase the quality.

The authors are requested to respond to the raised comments. The Contact Editor or the Co-ordinating Editor will have the final decision as to which of the peer reviewer’s’ comments need to be addressed in the event of disagreement between a peer reviewer and a team of authors.

- All peer reviewers will be asked to declare any potential conflict of interest.

- All peer reviewers are requested to adhere to the Committee on Publication Ethics (COPE) peer review ethical guidelines.

- ARCADIA: a tool for assessing the quality of peer-review reports in biomedical research

For some time now, CHBG authors are submitting their reviews to Cochrane’s central editorial office, which carries out the editorial processing and peer review, and provides methodological support.  

This mixed approach to editorial processing is happening while Cochrane moves to a new model of producing and publishing evidence syntheses. You can read more at https://futurecochrane.org/

The CHBG is one of the remaining functioning groups which continues with its activities. The CHBG is still conducting in-house peer review and quality assurance before a manuscript is submitted to the Cochrane Central Editorial Service for final peer review and publication.