Grey Literature Searching for Systematic Reviews in the Health Sciences

The growing volume of scholarly information makes it difficult for professionals to keep up with pertinent research literature. In the health sciences, standard bibliographic databases like PubMed that compile published articles are essential for the health care researcher and practitioner to obtain the latest peer-reviewed information. Many research results are available outside the formal publication process through unpublished reports, conference abstracts, preprints, and more, which are widely distributed across the internet. The systematic review, a type of publication that pulls together and then appraises findings from multiple individual clinical trials, helps inform health-care providers in their practices. Clinical information changes with each new trial or reanalysis, making recency of the findings to be especially importance. Grey literature is not peer-reviewed and omitting this time-consuming step may have the advantage of accelerating the process, which sometimes takes priority in rapidly evolving medical topics. On the other hand, cursory reviews have their costs as seen in the rise of preprints discussing the coronavirus pandemic in 2020. In this paper, the author discusses the unique needs of grey literature searching in the health sciences with a focus on the systematic review and similar publication types. A well conducted literature search for these reviews must be carefully managed in a replicable manner, thoroughly documented, and transparently reported, all challenges for grey literature searching. As an alternative to a highly sensitive strategy that a searcher commonly applies using standard bibliographic databases, the paper offers recommendations on a targeted approach specifying what grey document types to search and its resources, that balances practicality while maintaining methodological rigor. Finally, it includes a brief primer on using Google to find grey information.