Background: The Cochrane Library’s unique selling point is that it contains up-to-date reviews. However, this is not always the case: some reviews address historical questions; in some reviews the weight of evidence is such that no further trials are justified; and in others, the authors are in the process of updating the review. It is not immediately explicit to The Cochrane Library readership what the update status of a review is.

Objectives: To develop a clear, simple, transparent classification system for reviews to help readers understand whether our reviews are up-to-date or relevant.

Methods: We established a classification system based on two parameters: relevance and status. For relevance we identified two options: historical question, where an intervention or policy had been superseded by new medical developments (such as a new drug), and a current question, which was still relevant to current policy or practice. Thus a review that was no longer relevant to current practice was labelled as 'Historical: no update intended’. For reviews with a current question, we then used three status categories: 'up to date’, 'update pending’, or 'no update intended’. There then follows a slot, which allowed the author or editor to provide a little more detail. For 'update pending’ we might have given the number of trials waiting assessment and refer people to the 'trials waiting assessment section’. For 'no update intended’ we had two categories: 'review findings conclusive’, and 'topic covered in another review (see xxxx review)’.

Results: We have applied this to over 80 of our reviews and are currently inserting this in our published reviews. We will provide examples to illustrate how this works.

Conclusions: It is worth other groups considering adopting this approach.