How to update your review

Section 10.10 of the Reviewers' Handbook discusses some of the issues involved in updating your review and you should read it now.

The process of updating a Cochrane review will depend on the structure of the original review and the amount of new data available since the previous publication of the review. Probably the key factor in updating your review is to periodically update your literature search to assess if there are any new studies relevant to your review question. Some review groups will be able to give you more help with this than others. Some intermittently send new trials to reviewers, and all groups will maintain their own trial register. At the least you should keep an eye on the Cochrane Central Register of Controlled Trials, published on The Cochrane Library, and your review group's trial register

If new trials are identified, they need to be assessed for inclusion in your review using the same process (and form) as your original review. If they are to be included, data are extracted and entered into RevMan as in your original review. Don't forget to update your results text, discussion, conclusions, and abstract accounting for the new evidence, and highlight any differences it may have made in the What's New section of your review.

Sometimes updating your review results in new outcomes or comparisons being added. If this is the case, your original data extraction forms may need to be altered or extended, and piloted again. If this is the case, it might be necessary to go back to the original included trials and check that they did not include any information relevant to this new outcome or comparison.

Another possible update to a review is more methodological. As systematic review methodology advances, and the techniques available in RevMan are extended, it may be possible to perform additional analyses or strengthen existing ones not available in an earlier version of your review.

There is variability between review groups about when and if your updated review should again go through the process of editorial review. If your update involves no further analysis or change of result, it may not need to be refereed, however if there are new analyses and changes to conclusion, the same pre-publication process that was followed for your original review is likely to be repeated. You will need to check with your review group regarding their editorial policy for updated reviews.

If the update of your review leads to changes that you and your review group decide are important enough that anyone who read the review in the past should read it again, you should mark the review as a 'substantive update' when making the changes in RevMan.

Sometimes a search of the new evidence reveals there is no need to update your review. If this is the case, you should still update the date of the search strategy and indicate in the What's New section of your review that a search has been done, resulting in no additions or changes to your review.

Comments and Criticisms

The ability to comment on a review allows users of Cochrane reviews to contribute to the updating process. Section 10.11 of the Reviewers' Handbook discusses responding to criticisms and you should read it now.

A strength of Cochrane reviews is that they can be updated every quarter with publication of the new issue of The Cochrane Library. This means that you can alter or correct your review in response to valid criticism or comment, which is posted to your review group's Criticism Editor via the 'Feedback' or 'Comments/criticisms' on The Cochrane Library, or via the Cochrane website. Sometimes these criticisms take the form of letting reviewers know of a new or missed trial to be assessed for inclusion in an update, and sometimes they point out a potential error in the review which can be corrected, or the criticism responded to as appropriate.

Summary

While time consuming and ongoing, the process of updating Cochrane reviews is one of the key factors setting them apart from almost all other reviews. You need to carefully plan how and when you are going to update your review, and who will take responsibility to ensure it happens.