In some instances, a review may become too large and it may be desirable to split the review into two or more new reviews. Splitting reviews into more narrowly defined review topics, with potentially fewer studies, may ease updating and allow for sharing of the updating burden between several review teams.
Splitting a review implies creating at least one new citation version of a review, and the formal link with previous versions of the review may be lost. Splitting a review sometimes involves withdrawing the original review. A decision to split a review should not be made lightly and always in consultation with the CRG’s editorial board.
Cochrane Overviews of reviews (see Chapter 22) may facilitate the splitting of reviews, with the possibility of several more narrowly defined reviews (for example of single interventions for a particular condition) being combined in an Overview of all interventions for that particular healthcare condition.