Designing the review

Abstract

Overviews of systematic reviews are a relatively new research synthesis method that has emerged, due to the massive publication of systematic reviews and the need to answer complex clinical questions in a timely manner. Although the number of the overviews of systematic reviews has increased, no defi nitive guidelines regarding their conduct and reporting exist up to now. Some guidance regarding overview procedures can be, however, extrapolated from systematic review methodology, given the similarities that these two methods of evidence synthesis possess. On the other hand, considerable differences between overviews and systematic reviews exist regarding their scope, their eligibility criteria, and their analysis. It is therefore the aim of this chapter to provide a comprehensive guide through the steps of an overview of reviews, which will guide both interested readers and researchers willing to embark on such a journey themselves. This chapter's main emphasis is given to the most widely known type of overview, the umbrella reviews, as the same principles apply to almost all overviews. Finally, specifi c considerations are given for the other main type of overviews of reviews, namely, meta-epidemiological studies.