The co-publication of Cochrane Reviews in other journals is permitted in certain circumstances to support the dissemination of the findings of Cochrane Reviews. In general, the journal for the co-publication is likely to be a specialist publication (and therefore reaching a specialist audience) or published in a language other than English (reaching a wider audience). The underlying principles that govern co-publication include the following:

• Honesty and transparency are crucial, for example between the editorial teams of the Cochrane Review Group (CRG), the review authors, and journal editors/publishers, and also to inform the reader that different versions of the same data exist.
• The needs of end users are the prevailing consideration but the wellbeing of Cochrane, the Cochrane brand, and the Cochrane Database of Systematic Reviews (CDSR) are also crucial to any decision.
• Cochrane Review authors and CRG editorial teams who have contributed to the development of a Cochrane Review should be involved in any decision-making in relation to co-publication, and co-publication requires the permission of all the authors on the by-line of the Cochrane Review.
• The primary publication of a Cochrane Review (and subsequent updates) is in the CDSR; any exception to this requires permission from the Editor in Chief.
• All co-publication of Cochrane content needs to be consistent with the guidance of the International Committee of Medical Journal Editors (ICMJE), particularly the section on overlapping publication (accessed 22 August 2018).

Co-publications may take one of the following forms:

• Republication of the Abstract and/or Plain language summary, with the option of an accompanying original commentary (previously referred to as a ‘Cochrane Corner’).
• Shortened version of the full review.
• The above in English (language of original publication) or translated into a specific language.

Before proceeding with a co-publication, authors must also consider that the editor of the other journal may consider the publication to be redundant (duplicate) publication, that is, "publication of a paper that overlaps substantially with one already published in print or electronic media" (ICMJE recommendations on overlapping publications; accessed 22 August 2018); and that the authors of published Cochrane Reviews have granted Cochrane an exclusive licence for publication for the Cochrane Review, and the journal editor needs to be aware of this to ensure that the journal licensing does not impose restrictions on the original licenced content.

It is likely that a co-publishing journal will request that the abridged version of the Cochrane Review is peer reviewed and edited according to the journal’s editorial process, and it is possible that the authors will receive additional edits or feedback as part of this process. If appropriate, authors of the Cochrane Review should take these changes into account in the next update of the Cochrane Review. If, during the journal peer review process, authors are asked to change the way they present the review data (e.g. the results and/or conclusions change) in comparison to the CDSR version, the authors should discuss this with the CRG (and Editorial Methods Department, if necessary).

Note that if an original commentary is published alongside the co-publication, the journal must ensure to clearly differentiate between the author(s) of the commentary and the author(s) of the Cochrane Review (i.e. it should not appear that a Cochrane Review has been published by a different set of authors).

Authors considering co-publication of an updated version of a Cochrane Review must also consider the following:

• Cochrane Reviews should be updated in the Cochrane Database of Systematic Reviews (CDSR).
• The co-publication of any updated Cochrane Review must be substantially different to any previous co-publication of the same Cochrane Review (e.g. the conclusions are different).
• The editor of the journal may consider the publication to be redundant (duplicate) publication, that is, “publication of a paper that overlaps substantially with one already published in print or electronic media” (ICMJE recommendations on overlapping publications; accessed 22 Aug 2018).

Occasionally Wiley and the Cochrane EMD request to have sight of the proofs of the review article prior to publication. This is on a case-by-case basis and is primarily intended to ensure that co-published versions of the Cochrane Review adhere to the current co-publication policy.

For permission to co-publish an updated version of a Cochrane Review, please contact the Managing Editor of your CRG, using the ‘Permission to co-publish’ form (see Co-publication forms); your case may be referred to the Cochrane Editorial & Methods Department and Wiley for further guidance. The guidance given in the following section should also be followed: Arranging co-publication of a Cochrane Review.