This document describes how to construct a PICO search strategy to answer clinical questions using Embase. It explains that PICO search strategies are comprised of separate search strings for the patient population (P), intervention (I), and study type. It provides examples of search strings for common study types like randomized controlled trials, cohort studies, and systematic reviews. The document demonstrates how to build a prognosis PICO search strategy step-by-step, including combining the P, I, and study type search strings with filters and limits. The goal is to retrieve the most relevant evidence while excluding irrelevant publication types and animal studies.

1. PICO search strategies
Techniques and tips to answer well-developed clinical
questions using Embase
Wednesday, 22 April 2015
Maura Sostack, MLS, AHIP
EBM Librarian
Evidence-Based Medicine Center
Clinical Solutions
Elsevier Health Sciences

2. Learning Objectives
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 Describe the three concepts that form the basis of a PICO
search strategy.
 Create search filters using natural language words and
phrases and controlled vocabulary terms.
 Identify study type with its corresponding PICO question.

3. Table of Contents
 Deconstruct a protocol
 PICO search strategy
 The building blocks of a PICO search
 Use Embase to answer a well-developed prognosis PICO
question
 Summary
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4. DECONSTRUCT A PROTOCOL
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5. EBM Center Protocol: title page
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6. EBM Center Protocol: table of contents
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7. EBM Center Protocol: PICO question
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8. EBM Center Protocol: study eligibility
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9. EBM Center Protocol: exclusion criteria
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10. Protocol: search strategy
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11. PICO SEARCH STRATEGY
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12. PICO search strategy
A number of our PICO search strategies are comprised of three
sets of separate and distinct controlled vocabulary and natural
language terms:
• Terms for the health condition of the patient(s) or
population=P
• Terms for intervention(s)=I
• Terms for study type(s).

13. PICO search strategy : step by step
• Create P and I search strings.
• Use the Boolean operator AND to create a P&I search string set.
• Create a study specific search string or, if applicable, use a validated study
hedge.
• Use the Boolean operator AND to combine the study string set(s) with the P & I
set.
• Use the NOT Boolean operator to remove non-essential publication types and
animal studies.
• To reflect continuous updating, use the AND Boolean operator to add the ‘since
date’ search string to create the search of record.

14. PICO search strategy : caveat
Generally speaking, it is inadvisable to search on every
aspect of the clinical question within the confines of one
search strategy session.

15. THE BUILDING BLOCKS OF A PICO
SEARCH
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16. What’s in a name? Hedges; optimal filters; quality filters;
evidence-based filters=search strings
• Hedges and filters are search strings that contain controlled vocabulary
(EMTREE, MeSH, etc.) and natural language words and phrases.
• A validated hedge or filter contains both controlled vocabulary and natural
language words and phrases and has been put through a formal validation
process.
• Validated and un-validated hedges and filters are used to search for
American and British spelling of concepts and terms and to find incorrectly
indexed and e-pub ahead of print citations.
• Sets are created within the database interface when these hedges and
filters are used.
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17. Hedges and filters: +/∆
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+ ∆
Hedges, filters  Control
 Ensure retrieval of e-pub
ahead of print and online
first citations
 Incorrectly indexed
citations
 Complex and require
deep understanding of
basic & advanced search
techniques
 Require time to develop
 Require time to validate

18. Hedges, filters, & search term resources
McMaster University Health Information Research Unit (HIRU) Hedge Project:
http://hiru.mcmaster.ca/hiru/HIRU_Hedges_home.aspx
The InterTASC Information Specialists' Sub-Group Search Filter Resource:
https://sites.google.com/a/york.ac.uk/issg-search-filters-resource/
University of Pittsburgh MedTerm Search Assist:
http://www.hsls.pitt.edu/terms/
HLWIKI International: http://hlwiki.slais.ubc.ca/index.php/Filters_(ie._hedges)
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19. Question type Question definition Study methodology Embase study string
Diagnosis Diagnosis: the nature of
a disease; the
identification of an
illness.
Prospective, blind comparison
to a gold standard
(‘sensitivity and specificity'/de ) OR
(specificity:ab,ti )OR ('sensitivity and
specificity':ab,ti)
Prevention Prevention: to avert,
avoid or prevent the
onset of disease.
Randomized Controlled Trial
(RCT)
random*:ab,ti AND trial*:ab,ti OR
'randomized controlled trial'/de
Prognosis Prognosis: The forecast
of the probable outcome
or course of a disease;
the patient's chance of
recovery.
Prospective cohort; case-
control; case series
'incidence'/de OR 'mortality'/de OR
'follow up'/de OR 'prognosis'/de OR
'prediction and forecasting'/exp OR
'cohort analysis'/exp OR
incidence:ab,ti OR mortality:ab,ti OR
'follow up':ab,ti OR prognos*:ab,ti
OR predict*:ab,ti OR cohort:ab,ti
Embase: EBM Center’s study filters

20. Question type Question definition Study methodology Embase study string
Therapy /
Treatment
Therapy: the treatment
of disease. Therapy is
synonymous with
treatment.
Randomized Control Trial
(RCT)
(random*:ab,ti AND trial*:ab,ti) OR
('randomized controlled trial'/de)
Harms A measure of patient
safety considering
errors or mistakes
which result in harm to
the patient.
Observational studies;
nationally representative
prospective cohort studies
with multivariate adjustment
of adverse effects.
multivar*:ab,ti OR adjust*:ab,ti OR
'multivariate analysis'/exp
Embase: EBM Center’s study filters

21. Embase: systematic review/meta-
analysis filter
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('meta analysis'/de OR 'metaanalyses':ti
OR 'metaanalysis':ti OR 'meta analysis':ti
OR 'meta analyses':ti OR 'systematic
review':ti OR 'systematic review'/de OR
'cochrane database of systematic
reviews':jt)

22. Embase: publication types
We use this search string to NOT out specific
publication types:
'letter'/de OR 'editorial'/de OR 'note'/de OR 'short
survey'/exp
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23. Embase: animal studies
We use this search string to eliminate animal
studies from search results:
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NOT ('animals'/exp NOT 'humans'/exp)

24. Embase: ‘since date’ for citation
indexing
Search string to limit citations by a specific
indexing date:
[11-4-2011]/sd
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25. Prognosis PICO

26. EBM Center Protocol: Prognosis PICO question
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27. Protocol: search strategy
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28. 28

29. Prognosis PICO: P search strings
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30. Prognosis PICO: P & I search stings
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31. Prognosis PICO: study filter
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32. Prognosis PICO: NOT publications,
NOT animal studies and final results
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Search conducted on 7 April 2015

33. Prognosis PICO : combined harms, prognosis study
and systematic review/meta searches
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Search conducted on 21 April 2015

34. Prognosis PICO: study search of
record
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'community acquired infection'/de OR 'community acquired
infection':ab,ti OR 'community acquired disease':ab,ti AND
('pneumonia'/exp OR pneumonia:ab,ti) OR 'community acquired
pneumonia'/de OR 'community acquired pneumonia':ab,ti AND
('pneumonia outcomes research team':ab,ti OR port:ab,ti OR 'smart-
cop':ab,ti OR 'a-drop':ab,ti OR 'pneumonia severity index'/de OR
'pneumonia severity index':ab,ti OR 'psi':ab,ti OR 'curb 65 score':ab,ti
OR 'scoring system'/de) AND ('incidence'/de OR 'mortality'/de OR
'follow up'/de OR 'prognosis'/de OR 'prediction and forecasting'/exp
OR 'cohort analysis'/exp OR incidence:ab,ti OR mortality:ab,ti OR
'follow up':ab,ti OR prognos*:ab,ti OR predict*:ab,ti OR cohort:ab,ti)
NOT ('animal'/exp NOT 'human'/exp) NOT ('letter'/de OR 'book'/de OR
'editorial'/de OR 'note'/de OR 'short survey'/exp) AND [7-4-2011]/sd

35. 35
Prognosis PICO: harms search of
record
'community acquired infection'/de OR 'community acquired infection':ab,ti
OR 'community acquired disease':ab,ti AND ('pneumonia'/exp OR
pneumonia:ab,ti) OR 'community acquired pneumonia'/de OR 'community
acquired pneumonia':ab,ti AND ('pneumonia outcomes research
team':ab,ti OR port:ab,ti OR 'smart-cop':ab,ti OR 'a-drop':ab,ti OR
'pneumonia severity index'/de OR 'pneumonia severity index':ab,ti OR
'psi':ab,ti OR 'curb 65 score':ab,ti OR 'scoring system'/de) AND
(multivar*:ab,ti OR adjust*:ab,ti OR 'multivariate analysis'/exp) NOT
('letter'/de OR 'book'/de OR 'editorial'/de OR 'note'/de OR 'conference
paper'/de OR 'short survey'/exp OR 'conference abstract'/it) NOT
('animals'/exp NOT 'humans'/exp) AND [7-4-2011]/sd

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Prognosis PICO : systematic review and
meta-analysis study search of record
'community acquired infection'/de OR 'community acquired
infection':ab,ti OR 'community acquired disease':ab,ti AND
('pneumonia'/exp OR pneumonia:ab,ti) OR 'community acquired
pneumonia'/de OR 'community acquired pneumonia':ab,ti AND
('pneumonia outcomes research team':ab,ti OR port:ab,ti OR 'smart-
cop':ab,ti OR 'a-drop':ab,ti OR 'pneumonia severity index'/de OR
'pneumonia severity index':ab,ti OR 'psi':ab,ti OR 'curb 65
score':ab,ti OR 'scoring system'/de) AND ('meta analysis'/de OR
'metaanalyses':ti OR 'metaanalysis':ti OR 'meta analysis':ti OR 'meta
analyses':ti OR 'systematic review':ti OR 'systematic review'/de OR
'cochrane database of systematic reviews':jt) NOT ('animal'/exp
NOT 'human'/exp) NOT ('letter'/de OR 'book'/de OR 'editorial'/de OR
'note'/de OR 'short survey'/exp) AND [7-4-2011]/sd

37. Summary
Work with your investigators to:
• Identify terms and preferred filter methodology.
Deconstruct a protocol:
• Select the important concepts expressed in the P and I
portion of the PICO question.
Develop search strings:
• Use controlled vocabulary and natural language words
and phrases of British and American derivation to
construct search strings.
Use validated hedges:
• When applicable to your specific clinical question.
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38. THANK YOU!
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