Last update:
15-Jan-2020

The number of systematic reviews and meta-analyses in clinical research is still growing and now there is a need for a new methodology in the field of evidence synthesis, which will provide an overview of research data in a broad research topic. This new type of evidence synthesis, whose main feature is the inclusion of existing systematic reviews and meta-analyses, has been reported by different names, one of which is the umbrella review. Umbrella reviews are conducted to provide an overview of the body of information available for a given topic, and to compare and contrast the results of published systematic reviews and meta-analyses. Umbrella reviews are a very useful tool for clinical and policy decisions as well as for applying research findings into research recommendations and guidelines. An umbrella review collects and assess in a systematic way information from multiple systematic reviews and metaanalyses concerning all the outcomes. Using umbrella reviews, we understand the reliability and the validity of the research data, we find failures in a specific research area and we find the sources of decreased reliability and validity.

Key words: Systematic review, Meta-analysis, Methodology, Umbrella review.