Embase: Systematic Searching
BLITS:
Getting the Best
MLA 2011,
fromConvention Centre
Minneapolis
EMBASE.com
Minneapolis,
MN
Planning a Systematic Review
Planning the search strategy and process in advance
helps you to:
• Systematically retrieve the maximum number of
highly relevant references
• Extract the available evidence
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A checklist may be used to
review the search or used to help
set up a well planned search
Reviewing Search Strategies
• Checklist is taken from:
Jessie McGowan, Margaret Sampson, Carol Lefebvre. An
Evidence Based Checklist for the Peer Review of Electronic Search
Strategies (PRESS EBC). Evidence Based Library and Information
Practice 2010;5(1):149-54.
• The following article also helped inspire this presentation:
Sampson M, McGowan J, Cogo E, et al. An evidence-based
practice guideline for the peer review of electronic search
strategies. Journal of Clinical Epidemiology 2009 (Sep); 62(9):
944–952
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Choosing your database
There is some evidence of added value in searching Embase, as well as
MEDLINE, for studies for inclusion in systematic reviews, as the
additional studies identified contribute to the overall findings of the
review; this may be attributed in part to the greater coverage of some
languages other than English in Embase.
Lefebvre C, Eisinga A, McDonald S, Paul N. Enhancing access to reports of clinical trials published
world-wide – the contribution of EMBASE records to the Cochrane Central Register of Controlled Trials
(CENTRAL) in The Cochrane Library. Emerging Themes in Epidemiology 2008;5:13.
Embase Content Overview
Emtree: Biomedical thesaurus, over 60k terms
1947
1950
1974
2009
Embase: Fully indexed: Over 7,700 journals, 1974-
MEDLINE: 2,500 journals unique to Embase, mapped to Embase
indexing, 1950- (including MEDLINE Classic)
Embase Classic:
Digitally scanned and
re-indexed, 1947-1973
AIP and In Process:
Indexing added, from 2009
Conference Abstracts:
Indexing added, from 2009
Unique content in Embase
Presented by Carol Lefebvre MLA 2010
• ‘Embase is a rich source of reports of randomized trials
that are either not included in MEDLINE or not indexed
as trials in MEDLINE, especially reports in some
languages other than English’.
• ‘In addition to searching CENTRAL, people looking for
reports of randomized trials should search Embase, as
well as MEDLINE, for reports published in recent years
that have not yet been considered for inclusion in
CENTRAL’.
Ref: Lefebvre et al. Emerging Themes
in Epidemiology 2008 5:13
Embase vs MEDLINE
Randomized controlled trials
Language
Embase
Medline
Embase
advantage
Turkish
613
75
538
717%
Korean
134
46
88
191%
Portuguese
712
442
270
61%
Dutch
606
442
164
37%
Chinese
5366
3945
1421
36%
Polish
491
434
57
13%
Spanish
2316
2137
179
8%
French
3952
3904
48
1%
German
8393
8566
-173
-2%
Percent
Search date: 14 June 2010
Conferences
• 2009 – Elsevier started indexing conference abstracts in
Embase
• Currently nearly 400K conference abstracts in Embase
from 1K conferences
• Each abstract is searchable using Emtree
• Currently adding nearly 1K abstracts per day
• from journals and journal supplements published in
2009/2010/2011
• Conference abstracts are not in MEDLINE
• In BIOSIS for 2009/2010: “less than 165,000
records, of which just 11% have online abstracts”
• See http://www.embase.com/info/what-isembase/coverage for more information
Sample Review Question
Are there any risks associated with the administration of
antibiotics together with digoxin in a patient with
congestive heart failure who has contracted
pneumonia?
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Emtree (from Jan 2011)
• 60K preferred terms (more than 28K drugs and
chemicals, including all generic names recognised by
FDA, EMEA and WHO from 2000)
• >260,000 synonyms (>172,000 drugs and chemicals)
• 7,500 explosion terms (that define the hierarchical
structure)
• 78 subheadings (64 drug and 14 disease subheadings)
• 14 study types including Randomised Controlled Trial,
Systematic Reviews and the NEWLY introduced
Diagnostic Test Accuracy Study
• Links to over 21,000 CAS registry numbers
• All MeSH terms are included
• Updated 3 times a year (from 2011)
Benefits of Emtree
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Easy to search for terms and all synonyms
Comprehensive drug searching
Up-to-date
Explosion (tree) searching
Polyhierarchical structure
Natural language terminology
Inclusive terminology
Review www.embase.com/info/emtree for more
information
Start with Emtree
Find subject headings for your search
Click here to search further in an
Embase search form.
Click “nn Records” link to perform an
explosion search, if applicable.
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Reviewing an Emtree term
Consider the term’s History
Take note of any Synonyms listed
Look at the CAS registry number(s) displayed
Read the entry provided from
Dorland’s dictionary, when
available
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Emtree Term History
• If your term has not always existed in Emtree (this is after
1974), then perform a Field search of Article title (:ti)
using your term
• Review the Emtree terms in your retrieved records and
consider adding these subject headings to your search
strategy
• Review the abstracts to identify any alternative
expressions used by authors to add as additional free
text search terms.
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Free-text Term Searching
Perform a free text search for the Emtree term and all
synonyms in the title and abstract fields.
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Search unique fields
Include the Drug trade name (:tn) field with the Article title
and Abstract fields, where appropriate
Include the CAS registry number (:rn) displayed in the
Emtree record, when available
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Cannot find an appropriate Emtree
term?
• Perform a free text search in the article title field(:ti) using
your term
• Look through the resulting list of records and use “Add to
Clipboard” link for any articles deemed relevant
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Further tips for free text searching in
Embase (Elsevier only)
• Consider using truncation or wildcard characters (*, ?)
• Proximity operators are supported such as NEXT and NEAR
• When performing free-text searches, remember to
consider variant spellings including British and American
spellings and terminology
o e.g., tumor vs tumour; diaper vs nappy; pediatric vs
paediatric; otorhinolaryngology vs ear, nose and
throat; overuse injury vs repetitive strain injury
• Refer to www.trainingdesk.elsevier.com/embase and the
Quick User Guide for more guidance
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Filters
The most common
type of search filter
is for specific study
types, found in
Filters on Session
Results.
Other filters may
include publication
type .
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Diagnostic Test Accuracy Study
•Definition: Used for original studies
or systematic reviews which assess
how accurately a test distinguishes
humans or animals having a condition
or disease from those who do not.
Typically, the test under evaluation is
called the index test and its results are
compared to the results of the best.
•Previously: Did not exist
•From 2011: This is a new check tag
and unique to Embase
Embase study types
• Go to
http://pbt.up2els.com/sites/default/files/Embase%20chec
k%20tags%202011%20(4).27April2011.pdf for a list of
Embase study types and their definitions.
Save Search and Email Alert
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Coming in June 2011
Searches are saved
with all steps of
the strategy
clearly visible. The
user, can update
and rerun saved
search strategies
Coming in August 2011:
Editing your saved searches
Saved searches
can be edited,
and changes
previewed and
accepted.
When rerun, the
result count will
be updated
Thank you!
Contact us: http://embase.com/info/contact-us