Systematic Reviews - Part II
Karen Poole
karen.poole@kcl.ac.uk
Information Specialist – School of Biomedical Sciences
John Gale
john.r.gale@kcl.ac.uk
Information Specialist – Institute of Psychiatry
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Introduction
• More advanced search techniques using Ovid
software
• Reading a search strategy
• Grey literature: dissertations, conference
proceedings, Government reports, unpublished trials
etc
• Selecting studies to include in your review
• Documenting your search
• Where to go to get extra help/find out more
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An example of a search strategy
http://onlinelibrary.wiley.com/doi/10.1002/146
51858.CD006911.pub2/abstract
(navigate to Appendices for search strategy
via ‘Jump to’ box under Article tab).
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Practical
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Truncation – behavio* therapy
Wildcard searching – p?ediatrics
Adjacency searching – acute adj5 otitis media
Boolean operators – AND/OR/NOT
Floating sub-headings
Limiting to fields – PT, TW, AB
Subject headings vs free-text searching
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Using Filters
• Cochrane filter for RCTs
– http://www.cochrane.org/handbook/6411-search-filters
• SIGN
– http://www.sign.ac.uk/methodology/filters.html
• Centre for Reviews and Dissemination
– http://www.york.ac.uk/inst/crd/intertasc/rct.htm
• National Clinical Guideline Centre
– http://www.ncgc.ac.uk/Guidelines/
(navigate to appendix of specific guideline)
• McMaster University Hedges Project
– http://hiru.mcmaster.ca/hiru/HIRU_Hedges_home.aspx
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Grey Literature
“There are many definitions of grey literature, but it is
usually taken to mean literature that is not formally
published in sources such as books or journal
articles.” (Cochrane Handbook, 2011)
Examples of grey literature include:
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Technical or research reports from government agencies
Reports from scientific research groups
Working papers from research groups or committees
Doctoral dissertations
Some conference proceedings and official publications
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Publication bias
Papers with more ‘interesting’ results are more likely to
be:
• Submitted for publication
• Accepted for publication
• Published in a major journal
• Published in the English language
• Publication bias and outcome reporting bias:
agomelatine as a case example. Howland, R. H.
Journal of Psychoscocial Nursing and Mental Health
Services 49(9), September 2011
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Searching grey literature
• openGrey (System for Information on Grey
Literature) http://www.opengrey.eu/
• HMIC (The Healthcare Management Information
Consortium) – DH and King’s Fund – via Databases
list on OneSpace (King’s username and password)
• The National Technical Information Service (NTIS)
US and non-US government-sponsored research
www.ntis.gov/
• Libraries of specialist research organisations and
professional societies
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Conference Proceedings
Need to try and get full-text if possible
Can be found on:
• Web of Science
• Scopus
• Zetoc
Available on the Library Services database list
If full text isn’t available then order through the free
inter-library loan service (ILL).
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Theses and Dissertations
Some databases e.g. CINAHL and PsycInfo include
dissertations
WorldCat dissertations and Theses (OCLC) can be
accessed via OneSpace
AND – via Senate House – Index to Theses in Great
Britain and Ireland covers >500,000 theses
BUT – usually not full text so might need to get them via
ILL or travel to other libraries
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Trials Registers
Metaregisters of Controlled Trials – which bring together
several international sources
• The IFPMA clinical trial portal
• The International Standard Randomised Controlled
Trial Number (ISRCTN) register
• The WHO International Clinical Trials registry
• US register of clinical trials
• Other resources available in the Cochrane Handbook
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Handsearching
Physically searching the contents of journals,
conference proceedings and abstracts page by page
• Can identify articles not yet included in electronic
databases
• Articles or studies not indexed properly
BUT it’s impossible to search all journals so prioritise
using the results of your searches of databases such
as MEDLINE, EMBASE etc
You can also use the reference lists of papers you have
found earlier
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Direct Contact
• Making direct contact – usually by email – with the
authors or organisations who are experts in this field
• Authors often include their contact details in abstracts
• Can find out about ongoing or unpublished research
• Papers not on your list which authors might be aware
of
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Relevant internet resources
This does NOT mean Google or Google Scholar!
Look at specific relevant websites aimed at a particular
topic or subject search engines:
• Royal College and Society webpages for reports and
guidance
• NHS Evidence - http://www.evidence.nhs.uk/
– NHS search engine to locate evidence in health and
social care.
• TRIP database http://www.tripdatabase.com/
– clinical search tool to identify the highest quality clinical
evidence for clinical practice.
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Selecting studies and managing
references
• Merge and de-duplicate search results using
bibliographic software (make a copy of de-duped)
• Examine title and abstracts
• Best practice to retain evidence of what articles have
been excluded (and potentially why)
• Retrieve full text of potentially relevant articles
• Link together multiple reports
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How much is enough?
• Funding/time
– A broad search topic or searching more
databases/resources etc all increases the amount of time
required to sift results. No set timescale – depends on your
circumstances and any funding restrictions
• Focusing on RCTs/observational studies
– Widening a SR to include observational studies is likely to
increase the number of results you have to sift through.
• Personal/team knowledge – are all key known papers
in your subject area retrieved in the search?
– Amend search if not/include further databases – you would
expect key papers to be returned by a successful search
strategy if indexed in the databases you are searching.
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Inclusion/Exclusion Criteria
• Randomised Controlled Trials (RCTs) usually seen as
the gold standard [e.g. required for Cochrane SRs on
interventions if possible]
– This not always possible e.g. Interventions on pregnant
women
• How big was the trial?
– Will you only include trials with >5; >10; >50; >100 active
participants?
• Double-blind?
• Compared to placebo, waiting list or another
treatment?
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Study flow diagrams
Flow diagram should present the number of:
• unique records identified by the searches
• records excluded after preliminary screening (e.g. of titles and
abstracts)
• records retrieved in full text
• records or studies excluded after assessment of full text
• studies meeting eligibility criteria for the review
• studies contributing to the main outcome
• check lists and flow diagrams available from the PRISMA web
site
(PRISMA, 2009)
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Documenting your search
This is crucial because:
It forms a vital part of the systematic review in its own
right
Your searches should be able to be evaluated by other
researchers and reproduced in the future
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Documenting your search 2
What you need to record:
Information about the databases and interfaces searched including
dates covered and when you did your search
Full, detailed search strategies (copied and pasted) and the
number of records retrieved
Details of other searches including conference proceedings,
handsearching, contact with experts, reference lists and citation
searching and internet searching
You’ll also need to specify the criteria you use to select trials –
beyond the scope of this course!
There are examples at
http://www.york.ac.uk/inst/crd/SysRev/!SSL!/WebHelp/SysRev3.ht
m
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External Resources
• CRD’s Guidance for undertaking reviews in
healthcare
http://www.york.ac.uk/inst/crd/index_guidance.htm
• Cochrane Handbook
http://www.cochrane-handbook.org/
http://training.cochrane.org/
• Intertasc – www.york.ac.uk/inst/crd/intertasc/
• PRISMA – www.prisma-statement.org
• Critical Appraisal Skills Programme
http://www.casp-uk.net/
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EndNote courses
• Keep an eye out on Skills Forge
https://training.kcl.ac.uk
• 1:1s available with your Information Specialist whose
contact details you can find at:
http://www.kcl.ac.uk/library/support/spec/specialists.a
spx
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Further information and support
Library Services’ Searching for Literature guide
• User guides on specific interfaces and databases available at
http://www.kcl.ac.uk/library/help/guides.aspx
• Contact your school’s Information Specialist at
http://www.kcl.ac.uk/library/contact/spec/specialists.aspx
• EndNote pages at
http://www.kcl.ac.uk/library/help/bibsoftware/endnote/index.aspx
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