Is a one-size-fits-all ‘12-month rule’ appropriate when it comes to the last search date in systematic reviews?

The problem: conducted a year or more before submission of a systematic review (SR) paper can result in journal editors or peer-reviewers rejecting it. Their concerns are that findings from SRs with ‘out-of-date’ searches might provide decision-makers with misleading evidence. 1 Although recent technological advances have helped to speed up some review processes, 2 other methodological advances have increased the work required such that reviews often require longer than 12 months to produce useful and rigorous findings. This puts many SRs at risk of rejection by journal editors. argue that a blanket 12-month cut-off point for searches is not appropriate, that it may hinder the dissemination of important research, and may have a knock-on impact on reviewers’ willingness to undertake the most ambitious reviews. We also argue that not all SRs are equally at risk of being ‘out of date’ at 12 months; while intervention effectiveness reviews in fast-moving areas may become outdated well before 12 months, 3 others, such as qualitative evidence syntheses, are unlikely to have their findings substantially changed by the inclusion of new evidence. We focus on recent developments in SR designs, methods and technologies, to reflect on whether existing journal publishing guidelines are at odds with current SR approaches designed to improve review quality and usefulness.