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Grey Matters: a practical tool for searching health-related grey literature

Date: December 1, 2015
Result type: Resources

Go beyond the “grey zone”: Take advantage of some of the best IS expertise among HTA agencies worldwide with CADTH’s new online resource for grey literature searching, Grey Matters: a practical tool for searching health-related grey literature.

Now revised and updated, explore CADTH’s free online resource for grey literature searching, “Grey matters.”

Grey Matters: a practical tool for searching health-related grey literature

In order to use the tool:

  • save file
  • open file
  • “Open as read only?” will appear
  • click “No”



The Canadian Agency for Drugs and Technologies in Health (CADTH) provides Canada’s federal, provincial, and territorial health care decision makers with credible, impartial advice and evidence-based information about the effectiveness and efficiency of drugs and other health technologies. To achieve its mandate, CADTH produces a variety of publications that range from comprehensive systematic reviews and economic evaluations to more concise bulletins and updates.

In order to search for and retrieve the evidence base required to produce CADTH reports, the Information Services team has developed a grey literature checklist. Grey literature includes reports and government information that are not published commercially and that are inaccessible via bibliographic databases. The checklist is used to:

  • ensure the retrieval of all relevant health technology assessment (HTA), government, and evidence-based agency reports that may not be indexed in bibliographic databases such as MEDLINE
  • help document the grey literature search process, thereby increasing transparency and the potential for reproducibility
  • ensure that grey literature searching is done in a standardized and comprehensive way.


This checklist includes national and international HTA web sites, drug and device regulatory agencies, clinical trial registries, health economics resources, Canadian health prevalence or incidence databases, and drug formulary web sites.

Organized by topic, the checklist includes tips on navigating the web sites. Although the web sites are usually assigned to only one category, in many cases an individual web site may have relevancy in additional categories. The checklist does not supply background information on the agencies. If available, however, the name of the web site is a hyperlink to a brief description of the agency.

This checklist is meant to be used to document all aspects of the search process. This includes the documentation of all keywords used in the search and information about the availability of each web site as well as the use of a drop-down box beside each web site to indicate the success or relevancy of the retrieval.


The CADTH grey literature checklist is not exhaustive, but it does strive to be comprehensive regarding Canadian and international HTA agencies. To compensate for the focused characteristics of the checklist, supplemental keyword searches on two search engines are part of the process.

Commercial bibliographic databases, such as MEDLINE, EMBASE, and The Cochrane Library, are also searched for CADTH reports. Because this checklist focuses on grey literature, these bibliographic databases are not listed here (although we have included a few free databases that contain commercially published literature; for example, PubMed).

This publication is provided only online because it is a tool for evidence-based searching on the Internet. The checklist is updated regularly to reflect changes in web site addresses. Nevertheless, CADTH cannot be held responsible for occasional inaccuracies due to web site changes or due to the changing nature of the Internet.


This checklist is intended for the use of information specialists or researchers who are producing systematic reviews, HTAs, or economic evaluations.


CADTH Information Specialists play an integral part in the production of evidence-based publications and products at CADTH. With the growing importance of grey literature in evidence-based medicine and in an effort to ensure systematic and comprehensiveness in grey literature searching, we decided to develop this search tool. Calibrated over the years, it is now a useful tool for anyone engaged in searching for HTAs or drug assessments.