[How do authors of systematic reviews restrict their literature searches when only studies from Germany should be included?]

INTRODUCTION: The use of search filters (e. g. for study types) facilitates the process of literature searching. Regional limits might be helpful depending on the research question. Regional search filters are already available for some regions, but not for Germany. Our aim is to give an overview of applied search strategies in systematic reviews (SRs) focusing on Germany.

METHODS: We searched Medline (via Pubmed) applying a focused search strategy to identify SRs focusing on Germany in January 2016. Study selection and data extraction were performed by two reviewers independently. The search strategies with a focus on Germany were analyzed in terms of reasonableness and completeness relying on the Peer Review of Electronic Search Strategies (PRESS) criteria. A narrative evidence synthesis was performed.

RESULTS: In total, 36 SRs (13 written in English) were included. 78% were published in 2012 or later. The majority (89%) of SRs utilized at least two different sources for their search with databases and checking references being the most common. 17 SRs did not use any truncations, ten SRs did not restrict their search to Germany, six SRs reported to have searched for German OR Germany. Only ten articles searched for the term Germany (occasionally jointly with the term Deutschland) without any use of an adjective such as German.

DISCUSSION: There is a high interest in regionally focused SRs. The identified search strategies revealed a need for improvement. It would be helpful to develop a regional search filter for Germany that is able to identify studies performed in Germany.