Medical/clinical research

• Traditionally has relied on meta-analysis of published clinical trials.

• Now there is a strong endorsement for the consideration of inclusion of unpublished (grey) trials

• Found in sources like ClinicalTrials.gov Cochrane Central Register of Controlled Trials and Current Controlled Trials

Conference proceedings• Trials and studies are often reported in

conference presentations but over one-half of these never reach full publication

• “Failure to identify trials reported in conference proceedings might affect the results or threaten the validity of a systematic review” (Scherer 2007)

Cochrane Collaboration

“Published trials tend to be larger and show an overall greater treatment effect than grey trials. This has important implications for reviewers who need to ensure they identify grey trials, in order to minimise the risk of introducing bias into their review”

(Hopewell, 2007)

Campbell Collaboration

• “Campbell reviews must include a systematic search for unpublished reports (to avoid publication bias” (Campbell Collaboration, nd)

“Locating studies ..... [search] multiple sources of grey literature (websites, special registers, reference lists, listservs, personal contacts)” (C2 2010)

Joanna Briggs Institute• “In addition to databases of published

research, there are several online sources of Grey or unpublished literature that should be considered.”

• “Grey literature has the potential to complement and communicate findings to a wider audience, as well as to reduce publication bias.”

(Thomas, 2008)

Health research• For the evidence base to be comprehensive

and representative … “there is a need to tap into evidence from the widest variety of sources, so as to reflect the complexities of the issue and perceptions of end-users” (Tyndall, 2012)

• Reports, working papers, dissertations, focus groups, surveys, presentations, opinion polls, conference papers, crowd-sourcing ...

For complex health interventions

GL is needed to fill the information gap as “an essential part of the evidence base for practice in complex interventions, which may have multi-stakeholders, have multi-variables, have a lack of predictability and robust data and require a broad literature approach”

(Simkhada 2004)

For policy makers• policymakers, more than any other

research group, found GL especially relevant for context, and for its ability to reflect and map “how debate changes over time on a particular topic” (AcademyHealth, 2006)

• The recent Australian Dietary Guidelines consulted over 200 GL sources, making up 20% of their evidence base. Public consultation + expert review.

Dark data

Reusing research data

GRAPHC

References• AcademyHealth for the National Library of Medicine. Health Services Research and Health Policy

Grey Literature Project: Summary Report. Bethedsa, Md: National Library of Medicine, 2006. http://www.nlm.nih.gov/nichsr/greylitreport_06.html#_Toc124061657

• Campbell Collaboration. What is a systematic review? [nd] <http://www.campbellcollaboration.org/what_is_a_systematic_review/index.php>

• C2 Training materials 2010 http://www.campbellcollaboration.org/artman2/uploads/1/3_Information_retreival_South_Africa_2010-8-11.pdf

• Hopewell S, McDonald S, Clarke M. et al Grey literature in meta analyses of randomized trials of ‐health care interventions. Cochrane Database of Systematic Reviews 2007; Issue 2.

• Scherer RW, Langenberg P, von Elm E. Full publication of results initially presented in abstracts. Cochrane Database of Systematic Reviews 2007, Issue 2.

• Simkhada P, Knight J, Reid G, Wyness L, Mandava L. Chasing the grey evidence: a standardised systematic critical literature review approach: Paper presented at the Sixth International conference on grey literature “Work on Grey in Progress” 6-7 December 2004, New York <http://www.opengrey.eu/data/69/78/51/GL6_Simkhada_et_al_2005_Conference_Preprint.pdf>

• Thomas P. Shades of grey: the role of grey literature in systematic reviews. PACEsetters: A health care publication of the Joanna Briggs Institute: promoting and supporting Best Practice 2008; 5: 22-23

• Tyndall J, Merlin T. Lockwood, C. Impact of findings from grey literature on the outcomes of systematic reviews on interventions to prevent obesity among children: a systematic review. 2012 JBI Library Systematic Review, JBL000707 (JBI EBP database, viaOvid)