[Evidence syntheses in public health: An overview]

Since the beginning of the COVID-19 pandemic, there has been a high demand for rapid evidence syntheses to answer urgent public health questions. This article provides an overview of different types of reviews for public health questions and a synthesis of existing recommendations for the preparation of reviews. The aim is to support the planning of one's own review and the critical evaluation of published reviews.

The basis of this summary is an extensive search for guidelines and recommendations for different review types. Furthermore, internal journal clubs were held to determine knowledge needs and to critically discuss the various review types. Relating to the dissemination of results, fact sheets were developed for the individual review types including the most important information, prerequisites and work steps, as well as a decision tree for identifying the appropriate review type for the respective question.

Of the review types identified, Systematic, Rapid, Scoping, Umbrella, and Narrative Reviews were considered in more detail because they are particularly relevant to public health issues. Together with scoping and umbrella reviews, systematic reviews have the highest resource requirements due to the demands for extensive, systematic evidence synthesis and reproducibility. Rapid methods can accelerate the review process, for example by a very narrowly formulated question, a limited literature search, or the execution of certain steps by one instead of two persons.

Systematic Reviews may be considered as the gold standard, but they were developed primarily for clinical questions relating to interventions. This article, however, focusses on review types that consider the diversity of questions as well as the predominant use of quantitative methods in the field of public health. The fact sheets developed and the decision tree should enable low-threshold access to reviews while linking the perspectives of research and resource planning. They complement existing guidelines and recommendations.

To answer the diverse spectrum of public health questions, various types of reviews with various requirements and approaches are available. Given this diversity, a systematic introduction can be helpful for researchers planning or assessing a review.