This is an archived version of the Handbook. For the current version, please go to training.cochrane.org/handbook/current or search for this chapter here.

3.4.1  Where to start

Few methodological studies have been conducted to inform decisions about how and when to update systematic reviews (Moher 2008), however this is a rapidly evolving area and the guidance contained in this chapter will be regularly updated in line with new knowledge from methodological research. An update to a Cochrane review should usually occur every two years and must involve a search for new studies. If new studies are identified, they must be assessed for inclusion and, if eligible, incorporated into the review. While preparing an update to a review, additional issues may be considered, for example:

  1. any need for a change in research question and selection criteria of the review: e.g. addition of a new outcome or comparison, adding a newly specified subgroup analysis following improved methods for categorizing the condition; and

  2. change to methodology: e.g. inclusion of ‘Risk of bias’ assessment of currently-included studies (Chapter 8) or the addition of a ‘Summary of findings’ table (Chapter 11).