Google Scholar as a Resource for Systematic Reviews in Clinical Medicine

Authors of systematic reviews must select, among several options, the databases for searching articles for inclusion in their analyses. Google Scholar is readily available, easy to use, and widely accepted for everyday information searches, including scientific research. However, there is no consensus for its use as a resource in systematic reviews.

This study assessed the proportion of systematic reviews that used Google Scholar as a resource, the search strategies used, and the number of potentially missed articles if the search in Google Scholar was omitted and focused on PubMed, Cochrane Library, and Scopus. We also analyzed data from the most recent systematic reviews in clinical medicine indexed in PubMed that listed Google Scholar as one of the resources used for literature searches.

The term 'Google Scholar' was included in the title and/or abstract of 6.1% of systematic reviews archived by PubMed, compared to 37.5%, 36.1%, 31.8%, 18.5%, and 14.1% for the terms 'PubMed', 'Embase', 'Cochrane', 'Web of Science', and 'Scopus', respectively. Almost all (1029/1030) articles in the results section of the evaluated systematic reviews could be found in Google Scholar searches. If Google Scholar was omitted as a resource, the missed articles were 5% (53/1029). Twenty-one of 50 (42%) of the evaluated systematic reviews did not mention the number of articles identified from Google Scholar searches.

Google Scholar, as the most inclusive resource, should be used along with other established resources for systematic reviews. Advances in artificial intelligence may facilitate its use for this scientific purpose.