There is growing recognition that grey literature can be useful in systematic reviews. Searching for grey literature can be difficult, as it is not produced for commercial purposes, lacks bibliographic controls and may not be indexed in major databases.
This article has been cited by other articles in PMC. The inclusion of unpublished and grey literature is essential for minimizing the potential effects of publication bias. In issue 3,of the Cochrane Database of Systematic Reviews, there are 24 reviews of interventions for injury prevention published by the CIG.
These reviews examine a total of included studies, with The above figures highlight that there is a substantial amount of injury prevention research located in the grey and unpublished literature, which is never formally published.
Therefore, it is vital that review authors are proactive in their efforts to identify and obtain such research reports. However, identifying and obtaining reports on studies that have been completed, but never published, is extremely challenging.
There are a number of research data sources that we advise our authors to explore, in addition to the standard bibliographic database searching, in an attempt to identify unpublished reports. It incorporates not only records for controlled trials that have been downloaded from bibliographic databases, but it also includes records of unpublished studies identified through other means, such as handsearching.
It is generally limited to journal issues and conference proceedings collections, which include multiple individual reports or abstracts of studies that may not be adequately indexed elsewhere. Databases of unpublished and ongoing studies.
These are databases specifically containing grey literature, such as Zetoc http: With the increasing availability of reports and official documents on the Internet, searching for these documents is now easier, although full texts are not always available.
Authors can also target the websites of relevant organizations, which often have their own online, searchable publications library. Further studies can be identified by checking the reference lists of other eligible studies. The reference lists of any previous literature reviews can be particularly helpful for any further potentially relevant studies.
It can sometimes be worthwhile to contact experts in the field who are familiar with the literature and who might be able to advise review authors of any unpublished studies of which they are aware.
We would, therefore, suggest that authors make an effort to measure the extent to which publication bias may be present in their review, such as by examining funnel plots.
Grey literature, or evidence not published in commercial publications, can make important contributions to a systematic arteensevilla.com narrative review provides guidance about the benefits of. In a recently updated Cochrane methodology review, all five studies reviewed showed that published trials showed an overall greater treatment effect than grey literature trials (Hopewell b). Thus, failure to identify trials reported in conference proceedings and other grey literature might affect the results of a systematic review. To review systematically research studies, which have investigated the impact of grey literature in meta-analyses of randomized trials of health care interventions. Search strategy: We searched the Cochrane Methodology Register (The Cochrane Library Issue 3, ), MEDLINE ( to 20 May ), the Science Citation Index (June .
For further information about the work of the CIG, visit www. How important is publication bias? A synthesis of available data. Alderson P, Green S, eds. The Cochrane Collaboration open learning material.
Cochrane Database of Systematic Reviews ; Issue 2. Alcohol ignition interlock programmes for reducing drink driving recidivism. Cochrane Database of Systematic Reviews ; Issue 3.
Cochrane Database of Systematic Reviews ; Issue 1. CD [ PubMed ] 7. CD [ PubMed ] Many typical systematic review methods for searching, appraising, managing, and synthesising the evidence base can be adapted for use with grey literature and information.
Evidence synthesisers should carefully consider the opportunities and problems offered by including grey literature . It is therefore considered essential that active and extensive searching for unpublished and grey literature is undertaken as part of the review process for all CIG reviews, although we feel this to be particularly important for reviews of injury prevention interventions.
The above figures highlight. The System for Information on Grey Literature in Europe, is an open access database to bibliographical references of gray literature produced in Europe and allows you to export records and locate the documents in many research disciplines.
The purpose of this paper is to provide a detailed account of one systematic review team's experience in searching for grey literature and including it throughout the review.
We provide a brief overview of grey literature before describing our search and review approach. What is grey literature? Grey literature is “information produced by all levels of government, academics, business and industry in electronic and print formats not controlled by commercial publishing”.
and other published and unpublished sources. In addition, each Cochrane Review Group maintains and updates a collection of . Finally, we examined the section of the reviews describing the searching methods and documented if the review authors specifically indicated that they searched for unpublished studies (or grey literature), dissertations, or non-English studies.