guide
The Cochrane Library – Quick Guide
Claire Carolan and Melanie Bickerton, June 2012
QG MED007
[https://www.abdn.ac.uk/library/documents/guides/med/qgmed007.pdf]
Introduction
The Cochrane Library is a major resource for finding information on the effectiveness of healthcare
interventions. Updated regularly, it is a collection of six databases compiled by the Cochrane Collaboration, the
NHS Centre for Reviews and Dissemination, and others. The Cochrane Library is available online,
We recommend accessing the Cochrane Library via the University of Aberdeen Library, Special Collections
and Museums (LSC&M) home page.
This guide aims to give an introduction to the Cochrane Library. If you would like more help please contact
the Medical Library staff, email: [email protected] .

ACCESS INFORMATION:
UK-wide national provision to the Cochrane Library, access via the Aberdeen University Library,
Special Collections and Museums home page.
To access the Cochrane Library:
1. Go to the LSC&M home page at: www.abdn.ac.uk/library.
2.
Type: Cochrane in the ‘Search Our Collections’ box. The Cochrane Library is the first result on the list.
3.
Click on Cochrane Library to get to the Cochrane Library homepage.
4.
Click on Advanced Search to open the search page.
See information below/overleaf for information on how to search the Cochrane Library databases.
Free online video tutorials also available at www.thecochranelibrary.com/view/0/HowtoUse.html.
Content
Cochrane Database of
Systematic Reviews/
CDSR/Cochrane DSR
Database of Abstracts
of Reviews of Effects
Cochrane Central
Register of Controlled
Trials / CCTR
/CENTRAL
Full text of completed systematic reviews carried out by the Cochrane
Collaboration, plus protocols for reviews currently in preparation. Reviews are
updated in the light of new evidence and the date of the latest update is given.
(formerly Database of Abstracts of Reviews of Effectiveness):
Specially written structured abstracts of quality assessed systematic reviews
published elsewhere in the medical literature.
References to randomised control trials (RCTs) identified through hand
searching of journals and databases.
The Library also includes the Health Technology Assessment database (HTA), the NHS Economic
Evaluation Database (NHSEED) and the Cochrane Methodology Register (CMR), a database of articles on
methodology. There is also information about the Cochrane Collaboration itself.
The University of Aberdeen is a charity registered in Scotland, No SC013683
Definitions
Systematic Review
A review of a clearly formulated question that uses systematic and explicit methods
to identify, select and critically appraise relevant research, and to collect and
analyse data from the studies that are included in the review.
Randomised
controlled trial (RCT)
An experiment in which investigators randomly allocate eligible people into (e.g.
treatment and control) groups to receive or not to receive one or more interventions
that are being compared.
Meta analysis
A statistical technique for assembling the results of several studies in a review into
a single numerical estimate.
Search rules
1.
2.
3.
4.
Expand your search using the truncation symbol * e.g. depress* finds depression or depressive,
depressed etc. The truncation symbol can be used at the beginning and the end of your term.
* is also a wildcard to signify letter(s) within a word e.g. p*ediatric finds paediatric or pediatric.
Note that singular and plural alternatives are automatically searched.
Combine and separate your search terms using the Boolean Operators AND or OR or NOT.
If combining phrases in the same line, enclose each phrase in parentheses.
Starting your search
Search for your term(s) using both MeSH terms and natural language.
Searching for your term using the Medical Subject Headings (MeSH Descriptor)
1.
Click on Advanced Search. Click on MeSH Search. Enter your first term into the Search for a
MeSH Descriptor box. Click the Thesaurus button.
The MeSH descriptors make up the thesaurus of the Cochrane Library. When you search for a term
using the MeSH Thesaurus button, the database will search for all of the MeSH descriptors that
contain your term. By selecting the MeSH descriptor through the Thesaurus, the database will
retrieve results containing the MeSH descriptor and related narrower terms (e.g. the MeSH
descriptor Myocardial Infarction will find that term, but also Anterior Wall Myocardial Infarction;
Inferior Wall Myocardial Infarction; Myocardial Stunning; Shock, Carcinogenic etc.).
2.
A list of MeSH Descriptors (MeSH terms) will now be displayed. Click on the relevant descriptor to
see its place in the Cochrane Library’s Thesaurus Tree(s). These trees show where the descriptor
has been indexed in relation to broader and narrower terms.
3.
If you wish to search for the descriptor only, select the Search this term only box. If you wish to
search for the descriptor and its narrower terms, select the Tree Number * box (es). The Explode
box is a quick way to select all of the Trees.
4.
To further narrow down your search, click on the Add qualifier restriction drop-down menu. You
can select as many qualifiers as required. Click on the View Results button.
5.
Repeat steps 1-5 for all of your terms. Click on Search History. Scroll down to your Current Search
History. Each search has a number.
Searching for your term using Natural Language
There are 2 ways to search using natural language
1.
2.
Using the Advanced Search option, type in your first term into the search box. Select Title,
Abstract or Keywords from the drop-down menu.
Click the Search button.
Go to the Search History page and type in your first term into the search box. Directly after the term
enter the field codes to narrow down your search. The field code for title is ti; for abstract is ab; for
keyword is kw. So an example would be myocardial-infarction; ti, ab
Click the Go button.
Beware: When you search using natural language, you will not retrieve singular/plurals,
American/UK spellings e.g. mouse/mice, esophagus/oesophagus. Natural language searching can
be used where a MeSH search gives nothing useful, but should be used with care – MeSH
searching is usually more accurate.
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Combining your searches
Once you have looked for one or more term(s), go to the Search History page.
The Current Search History will look like this:
Each search has an ID number.
Type the relevant ID numbers and the hash symbol (e.g. #1 AND #2; #2 OR #5) in the Search for
box using AND or OR or NOT to combine the search terms.
AND narrows your search. It will only retrieve results where both terms occur in the same reference.
OR broadens your search. It will retrieve results on Term 1 or Term 2 whether or not they are
related.
NOT removes an unwanted term from any set.
Displaying and viewing the results
Click on the appropriate line (in the example above you would click on #1 AND #2) to open the
Search Results page. The Search Results page displays the total number of hits and the number of
hits in each database. By default, the Cochrane Reviews (CDSR) results are displayed. Click on the
title of a database to view the records retrieved. The order of the results can be resorted by
relevance (Match %), date or record title (alphabetical ).
Scroll down the screen to browse the record entries, and click on the title to view the full text (CDSR
and CDMR databases only) or the structured abstract.
The record appears on the right-hand side of the screen. To the left is a table of contents, which enables
you to jump to a particular section. This can be useful: in the Cochrane Reviews (CDSR), jump to
Authors’ conclusions to see at a glance the Implications for practice and Implications for research.
The left-hand frame also provides a link to the PDF of the full text.
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Saving and Exporting results
Saving records
1.
Select the relevant result(s) by checking the box to the left of the result.
2.
Scroll down to the bottom of the page. Click the Export Selected Citations button.
3.
Select your export options: Export Type and File Type (most likely will be PC).
4.
Click on Export Citation button.
5.
A file download box will open. Click on Save.
6.
Select appropriate location to save the file (e.g. your H: Drive).
7.
Click on Save again.
Exporting bibliographic details to a reference management package such as RefWorks.
Information on how to import references from the Cochrane Library into RefWorks can be found in
the library guide Instructions for Importing Records from Information Databases into RefWorks
at: www.abdn.ac.uk/library/documents/guides/rfw/importing.pdf
To import records from The Cochrane Library provided by Wiley Online Library follow the instructions
for Wiley Interscience.
To import records from The Cochrane Library provided by OVID follow the instructions for Medline
provided by OVID.
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Workshops on using RefWorks can be booked online via www.abdn.ac.uk/coursebooking/
NOTE
Personal Account
A Personal Account with the CL allows you to create and maintain a private workspace for your
saved search strategies and AutoAlerts. There are also more features available to you in the search
results screen. To create a Personal Account do the following:
1.
Log in to the CL using your University username and password.
2.
Once in the CL, go to the Advanced Search page within the database. Click on Login (top righthand corner) and click on Register now and complete the form.
The odds-ratio diagram in the CDSR
To view the odds-ration diagrams
To view the odds-ratio diagrams (found in most complete reviews in CDSR), click on the record title in
your search results. The table of contents for the review appear in a column on the left-hand side of
the screen. Click on the Figures option in the table of contents.
What is an odds-ratio diagram?
Each review on the CDSR combines the results of individual RCTs, usually found under the link Figures.
Specific outcomes are monitored for each group in the RCT and results may be positive or negative.
Meta analysis is the method of combining the results of different RCTs (for the same intervention). An
odds-ratio diagram intends to present what are complicated results in a clear visual fashion.
The odds of an event are calculated as the number of events divided by the number of non-events. An
odds-ratio result is calculated by dividing the odds in the treated or exposed group by the odds in the
control group.
In the odds-ratio diagram each individual trial in the odds ratio result is represented by a box, the horizontal
line through it representing the confidence interval for that result. The meta analysis result is represented by
a diamond the width of which represents the confidence interval. The horizontal axis shows the odds ratio.
The vertical line represents an odds ratio of one and is known as the line of no effect.
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Interpreting an odd-ratio diagram
In order to interpret an odds-ratio diagram you must ascertain:

The nature of the intervention under investigation.

The outcomes being measured.

Whether the outcome is positive or negative.

Whether the odds ratio for the summary result(s) are greater or less than one (to the right or to
the left of the vertical line which represents no effect).

Whether the confidence intervals (represented by horizontal lines) cross the vertical (no effect) line.

Whether the summary result (at the bottom of the diagram and represented by a black diamond
rather than a blue box) 'looks' as if it is a fair representation of the individual trial results.
The results that you read from the odds-ratio diagram should agree with the textual results and
implications given in the main body of the review.
Summary of findings
An odds ratio to the left of the vertical line means less of the outcome and to the right, more.
A beneficial result for a bad/negative outcome is an odds ratio to the left of the vertical line (odds ratio of
less than one).
A beneficial result for a good/positive outcome is an odds ratio to the right of the vertical line (odds
ratio of more than one).
For More Information:
The Cochrane Handbook for Systematic Reviews of Interventions is at: www.cochrane-handbook.org/
Tutorials and User guides can be found at: http://olabout.wiley.com/WileyCDA/Section/id-390244.html
Deeks, John. Bandolier. Swots corner: What is an odds ratio? [webpage on the Internet]. Oxford: Bandolier;
2006 [cited 2010 August 6] Available from: www.medicine.ox.ac.uk/bandolier/band25/b25-6.html
Problems: If in difficulty, please ask the library staff – we are always happy to help.
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