- Peer reviewers should be experts in the manuscript’s content area, research methods, or both; a critique of writing style alone is not sufficient.

- Peer reviewers should be selected based on their expertise and ability to provide high quality, constructive, and fair reviews.

- For research manuscripts, editors may, in addition, seek the opinion of a statistical reviewer.

- Peer reviewers advise editors on how a manuscript might be improved and on its priority for publication in that journal.

- Editors decide whether and under which conditions manuscripts are accepted for publication, assisted by reviewers’ advice.

- Peer reviewers are sometimes paid for their efforts but usually provide their opinions free of charge, as a service to their profession.

- Editors should require all peer reviewers to disclose any conflicts of interest, financial or otherwise, related to a particular manuscript and should take this information into account when deciding how to use their review. Generally speaking, people with a direct financial interest in the results of the manuscripts should not be reviewers.

- To be considered peer reviewed, a journal should have obtained external reviews for the majority of manuscripts it publishes, including all original research and review articles. Some editors request peer review for other kinds of articles, such as opinion pieces (commentaries/editorials) and correspondence. To have been peer reviewed, a manuscript should have been reviewed by at least one external reviewer; it is typical to have two reviewers and sometimes more opinions are sought.

- Editors of peer-reviewed journals need not send all submitted manuscripts out for review. Manuscripts that seem unlikely to be published in that journal may be returned to authors without external review, to allow authors to submit the manuscript to another journal without delay and to make efficient use of reviewers’ and editors’ time.

- Editors should state their journal’s peer review policies, including which kinds of article are peer reviewed and by how many reviewers, in the instructions for authors.

- Editors should also periodically publish statistics describing their journal’s review process, such as number of manuscripts submitted, acceptance rate, and average times from manuscript submission to rejection letter to authors and, for accepted manuscripts, time to publication.

- Editors should avoid using only author-recommended peer reviewers to review a paper.

- Editors should not use an author-recommended reviewer unless the person’s contact information is obtained from an independently validated source, e.g., from the reviewer’s publications or referred by a member of the Journal’s editorial board. Note that email addresses with top level domains such as .edu are more likely to be reliably linked to the correct individual than those with other less tightly controlled domains (e.g., gmail or yahoo accounts). However, editors should not require reviewers to use their .edu or other professional email addresses because some institutions may not have reliable email access, particularly in low or middle income countries, and their faculty may prefer to use non-institutional email addresses. [In these limited cases, Editors may want to encourage potential reviewers to include the non-institutional email address on their institutional Web page]. Editors should consider applying similar diligence to reviewer-suggested reviewer names and emails.

- Editors should make every effort to find expert reviewers in the topics(s) addressed in the manuscript who are free of significant conflicts of interest. These efforts include the editors’ own expertise, and use of electronic databases, manuscript reference lists, editorial board recommendations, journal database searches, and the like. For highly specialized areas, chairs of departments and the like may have suggestions as to faculty with expertise.

- To avoid inviting peer reviewers with significant conflicts of interest, editors generally should exclude from consideration:

(a) individuals who have coauthored manuscripts with the authors in the recent (e.g., 10 years) past,

(b) individuals who work at the same institution as the authors, particularly if they are in the same area as an author or the institution is small, and

(c) individuals who have other conflicts of interest, financial or otherwise, for or against the paper.

If editors make exceptions to these general principles when inviting reviewers, they should keep in mind the exception and its potential implications for the reviewer’s recommendations.

- Potential reviewers should be asked to recuse themselves prior to accept a peer review invitation if they have a conflict of interest for or against the manuscript or if they are otherwise unable to review the manuscript objectively. Reviewers who agree to review and then discover a potential conflict should contact the editor.

- Every peer-reviewed medical journal should have its own Conflict of Interest policies for authors, reviewers, and editors that are publicly available and these should be provided to potential reviewers (see here).

- Journal peer review systems should include a step asking the reviewers to report their potential conflicts of interest, requesting explanation and preventing review without editor intervention if reviewers answer in the affirmative.