1. Developing Search Methods
for Systematic Review
Farhad Shokraneh
Medical Information Specialist
Cochrane Schizophrenia Group
Presentation at: Developing Search Methods for Systematic Review Workshop; September 19, 2015; Sina
Trauma and Surgery Research Centre , Sina Hospital, Tehran University of Medical Sciences, Tehran, Iran
DOI: 10.13140/RG.2.1.2744.6248
Permanent Link: http://dx.doi.org/10.13140/RG.2.1.2744.6248

2. Introduce yourself, please!
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3. What is this workshop about?
• Developing your search protocol
• Running your searches
• Managing your search results and alerts
• Documenting and reporting your search
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4. Typology of Reviews
• Traditional/Narrative Reviews
• Scoping Reviews
• Systematic Reviews
– A research review!
• etc.
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5. Steps to develop a search protocol
• Verifying your research question [Already?]
• Turning your research question into PICO
• Breaking each PICO concept into keywords
• Providing the list of search resources/methods
• Developing search strategy for each database
• Peer-review of search strategies
• Revising the search protocol and finalizing
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6. Turning research question into PICO
• Extract main concepts also referred as:
– PICO/PECO
– PICOS
– PICOT
– etc.
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7. PICO for interventional reviews
• P for
– Patients [age group, gender, etc.]
– Population
– Problem
– Participants
• I for
– Intervention
– Index Test
– Exposure
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8. PICO for interventional reviews
• C for
– Comparison [Intervention/Index Test]
– Control Group
– Comparator
• O for
– Outcomes [Including Scales and Measurements]
• T for
– Time
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9. PICO for interventional reviews
• S for
– Study design [research methodology]
• S for
– Setting [rural/urban, in/outpatient, hospital, EM, etc.]
• Anything missing from PICO?
– Anatomy [what part of body]
– Geography [certain country?]
– etc.
• Usually we have at least one P, at least one I, and
at least one S [study design] in an interventional
review search
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10. Practice: What is your PICO?
• Create and save a word document and name
it properly. This document will be your search
methods/report at the end
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11. Breaking PICO concepts into words
• Famous Example:
– Concept:
• Cancer
– Keywords:
• Cancer
• Cancers
• Cancerous
• Neoplasm
• Neoplasms
• Neoplasma
• Neoplasmatic [?]
• Neoplastic [?]
• Tumor
• Tumors
• Tumour
• Tumours
• Cyst [?]
• Cysts [?]
• Malignancy
• Malignancies
• Malignant
• Metastasis
• Metastases
• Metastatic
• Words end in ‘-oma’ [?]
– Carcinoma
– Carcinogen [?]
– etc.
• O_0
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12. Breaking PICO concepts into words
• Why are so many keywords for one concept?
– Synonyms [generic drug name vs. commercial drug name]
– Derivatives from same root [cancer and cancerous]
– Highly relevant/connected word [metastasis]
– Specific/broad terms of concept [cancer vs. carcinoma]
– British/American spelling variations [tumor]
• Aetiology; behaviour; centre; randomised; etc.
– Word in other languages
– Have I missed anything, share your experience?
Consider all the aforementioned roles!
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13. Breaking PICO concepts into words
• Methods to collect the keywords
– Objective Methods
• Use Controlled Vocabulary [MeSH, EMTREE, CINAHL Headings, etc.]
• Checking previous systematic reviews
• Searching for published search strategies [search filters]
– Subjective Methods
• Your mind
• Reading reviews or doing a literature review
• Experts write reviews! Ask experts!
• Test search results
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14. Breaking PICO concepts into words
• Medical Subject Heading (MeSH) could be used for
several purposes and two of them are related to this
workshop:
– Using MeSH for collecting words
– Using Mesh for subject searching
• Using MeSH for collecting words
– Accessing and Searching MeSH
– Structure of a MeSH Record
– Options in MeSH Search Interface
– Using Entry terms and MeSH heading as words
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15. Practice: Break your PICO down
1. Your mind
2. Experts
3. MeSH
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16. Providing the list of search resources/methods
• First things first
– This list depends on
• Your topic
• Your time and money
• Human resources
• Funder’s/grant’s criteria
• International guide that you follow
• Accessibility of resources
• Minimum requirements for publication/presentation
• etc.
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17. Providing the list of search resources/methods
• First Search Level: Databases
– Your research questions is about medicine/health? [Broad Topic]
• MEDLINE and/or PubMed [What is the difference?]
• EMBASE
– Yours research question is interventional? [Study Design]
• Cochrane Library [CDSR; DARE; HTA; CENTRAL; CMR; NHS EED]
– Yours research question is about nursing or psychology?
[Specific/Narrow Topic]
• CINAHL
• PsycINFO
– The disease/intervention’s geographical epidemiology
[National/Regional Databases]
• Chinese Databases for Chinese Traditional Medicine
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18. Providing the list of search resources/methods
• Second Search Level
– Happens in search step
• Grey Literature [Please Refer to Webinar]
– ClinicalTrials.Gov
– WHO ICTRP
– Dissertations databases
– Reports and guidelines
– Conference abstracts databases
– Contacting the authors, researchers, and organizations
– Hand-searching of journals and conference
– Happens during research
• Retrospective Approach
– References of Screened Full Texts
– References of Previous Systematic Reviews
• Prospective Approach
– Citations to Screened Full Texts
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19. Practice: List your search sources
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20. Practice: Registration in sources
• Please register in
– Ovid SP [for MEDLINE]
– NCBI [for PubMed]
– Cochrane Library
• And note your username and password in a
safe place
• If you have done it before it is not required
again, please use your login info and login in
Ovid SP
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21. Developing search strategy for each database
• How to put all words together and make the
database understand what we want?
• Formulation of search strings [formula?]
– A time travel to high school mathematics
– Set theory and Venn diagrams
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22. Developing search strategy for each database
• Boolean Operators
– Use OR
• among the words that you have collected for one concept
• Put whole string between two parentheses to make a ‘set’
• Example
– String 1: (Cancer OR Cancers OR Cancerous OR Tumour OR
Tumours OR Tumor OR Tumors OR Metastasis OR Metastases OR
Metastatic OR Malignancy OR Malignancies OR Malignant OR
Neoplasm OR Neoplasms)
– String 2: (Aspirin OR Acetylsalicylic Acid OR Acylpyrin OR
Aloxiprimum OR Colfarit OR Dispril OR Easprin OR Ecotrin OR
Endosprin OR Magnecyl OR Micristin OR Polopirin OR Polopiryna
OR Solprin OR Solupsan OR Zorprin OR Acetysal)
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23. Developing search strategy for each database
• Boolean Operators
– Use AND
• To compine PICO concepts back together
• Example
1. (Cancer OR Cancers OR Cancerous OR Tumour OR Tumours OR
Tumor OR Tumors OR Metastasis OR Metastases OR Metastatic
OR Malignancy OR Malignancies OR Malignant OR Neoplasm OR
Neoplasms)
2. (Aspirin OR Acetylsalicylic Acid OR Acylpyrin OR Aloxiprimum OR
Colfarit OR Dispril OR Easprin OR Ecotrin OR Endosprin OR
Magnecyl OR Micristin OR Polopirin OR Polopiryna OR Solprin OR
Solupsan OR Zorprin OR Acetysal)
3. 1 AND 2
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24. Developing search strategy for each database
• Boolean Operators
– Use NOT
• To exclude a set from your search results
• We are not using NOT so often
• One of popular uses of NOT is in excluding animal studies
– We’ll see soon!
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25. Developing search strategy for MEDLINE via
Ovid SP
• So for now this is my search strategy but:
1. (Cancer OR Cancers OR Cancerous OR Tumour OR Tumours OR
Tumor OR Tumors OR Metastasis OR Metastases OR Metastatic
OR Malignancy OR Malignancies OR Malignant OR Neoplasm OR
Neoplasms)
2. (Aspirin OR Acetylsalicylic Acid OR Acylpyrin OR Aloxiprimum OR
Colfarit OR Dispril OR Easprin OR Ecotrin OR Endosprin OR
Magnecyl OR Micristin OR Polopirin OR Polopiryna OR Solprin OR
Solupsan OR Zorprin OR Acetysal)
3. 1 AND 2
Can I make it shorter? Of course!
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26. Developing search strategy for MEDLINE via
Ovid SP
• Truncation or stemming a root word in Ovid SP
– Search the root of the word and put $ at the end to
get the rest of root variations
– Search spelling variation of one or zero character
using wild card putting ? in middle or end of a word:
Tumo?r?
1. (Cancer$ OR Tumo?r? OR Metasta$ OR Malignan$ OR Neoplas$)
2. (Aspirin OR Acetylsalicylic Acid OR Acylpyrin OR Aloxiprimum OR
Colfarit OR Dispril OR Easprin OR Ecotrin OR Endosprin OR
Magnecyl OR Micristin OR Polopirin OR Polopiryna OR Solprin OR
Solupsan OR Zorprin OR Acetysal)
3. 1 AND 2
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27. Developing search strategy for MEDLINE via
Ovid SP
• What part [field] of the paper do we search? Title, abstract, text
words, authors, journal name, publication year!
• For field searching in Ovid for title and abstract use ‘default’ field
tags after end parenthesis: .ti,ab.
1. (Cancer$ OR Tumo?r? OR Metasta$ OR Malignan$ OR
Neoplas$).ti,ab.
2. (Aspirin OR Acetylsalicylic Acid OR Acylpyrin OR
Aloxiprimum OR Colfarit OR Dispril OR Easprin OR Ecotrin
OR Endosprin OR Magnecyl OR Micristin OR Polopirin OR
Polopiryna OR Solprin OR Solupsan OR Zorprin OR
Acetysal).ti,ab.
3. 1 AND 2
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28. Developing search strategy for MEDLINE via
Ovid SP
• Adding MeSH for subject searching
– Where is my main concepts as MeSH [if exist]?
1. exp Neoplasms/ OR (Cancer$ OR Tumo?r? OR Metasta$
OR Malignan$ OR Neoplas$).ti,ab.
2. exp Aspirin/ OR (Aspirin OR Acetylsalicylic Acid OR
Acylpyrin OR Aloxiprimum OR Colfarit OR Dispril OR
Easprin OR Ecotrin OR Endosprin OR Magnecyl OR
Micristin OR Polopirin OR Polopiryna OR Solprin OR
Solupsan OR Zorprin OR Acetysal).ti,ab.
3. 1 AND 2
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29. Developing search strategy for MEDLINE via
Ovid SP
• If you want to add another [set] for study design
[for example RCT], you can use the available
search filters for example Cochrane MEDLINE
[Ovid] filter for RCTs
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30. Developing search strategy for MEDLINE via
Ovid SP
4. randomized controlled trial.pt.
5. controlled clinical trial.pt.
6. randomized.ab.
7. placebo.ab.
8. drug therapy.fs.
9. randomly.ab.
10. trial.ab.
11. groups.ab.
12. 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11
13. exp animals/ not humans.sh.
14. 12 not 13
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31. Developing search strategy for MEDLINE via
Ovid SP
To sum up the first strategy for MEDLINE via Ovid:
1. exp Neoplasms/ OR (Cancer$ OR Tumo?r? OR Metasta$ OR
Malignan$ OR Neoplas$).ti,ab.
2. exp Aspirin/ OR (Aspirin OR Acetylsalicylic Acid OR Acylpyrin OR
Aloxiprimum OR Colfarit OR Dispril OR Easprin OR Ecotrin OR
Endosprin OR Magnecyl OR Micristin OR Polopirin OR Polopiryna
OR Solprin OR Solupsan OR Zorprin OR Acetysal).ti,ab.
3. (randomized controlled trial or controlled clinical trial or pragmatic
clinical trial).pt. or (randomi?ed or randomly or placebo or trial or
groups).ab. or drug therapy.fs. not (animals not (humans and
animals)).sh.
4. 1 AND 2 AND 3
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32. Practice: Let’s finish the first strategy
• Let your colleague peer-review your search
strategy using PRESS check list
• Export the search results in EndNote format
and name the exported file properly
• Save the search and set the alert
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33. Operators to be use carefully
• NOT [as explained]
• Adjacency: e.g. in Ovid SP: spinal adj2 cord
• Exact Phrase: e.g. "Spinal Cord"
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34. Differences in search among databases
MEDLINE via Ovid SP PubMed Cochrane Library
Boolean and, or, not AND, OR, NOT and, or, not
Set Making () () ()
Truncation $ * *
Wild Card ? Automatically Happens
Adjacency adj, adj1, adj2 NEAR, NEAR/1, NEXT
Phrase "" "" ""
Field Tags .ti. .ab. .ti,ab. .tw,ot.
After end parenthesis
[ti] [tiab] [tw]
After each word
:ti :ti,ab :ti,ab,kw
MeSH exp Neoplasms/ Neoplasms[MeSH] MeSH descriptor:
[Neoplasms] explode all trees
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35. Practice: Adopting your MEDLINE Ovid SP
search strategy for PubMed
Note: Hear is Cochrane’s search strategy for RCTs in PubMed:
Separated strings:
1. randomized controlled trial[pt]
2. controlled clinical trial[pt]
3. randomized[tiab]
4. placebo[tiab]
5. drug therapy[sh]
6. randomly[tiab]
7. trial[tiab]
8. groups[tiab]
9. #1 OR #2 OR #3 OR #4 OR #5 OR #6 OR #7 OR #8
10. animals[mh] NOT humans[mh]
11. #9 NOT #10
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36. Practice: Adopting your MEDLINE Ovid SP
search strategy for PubMed
Note: Hear is Cochrane’s search strategy for RCTs in PubMed:
One go string:
(randomized controlled trial or controlled clinical trial or
pragmatic clinical trial).pt. or (randomi?ed or randomly or
placebo or trial or groups).ab. or drug therapy.fs. not (animals
not (humans and animals)).sh.
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37. Practice: Adopting your MEDLINE Ovid SP
search strategy for PubMed
• Let your colleague peer-review your search
strategy using PRESS check list
• Export the search results in EndNote format
and name the exported file properly
• Save the search and set the alert
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38. Practice: Adopting your MEDLINE Ovid SP
search strategy for Cochrane Library
Note: you don’t need to use RCT filter for
Cochrane Library
• Let your colleague peer-review your search
strategy using PRESS check list
• Export the search results in EndNote format
and name the exported file properly
• Save the search and set the alert
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39. Limitations in search and publication bias
• When to Use Date/Time Limits
– When updating a review if you have forgotten to set alert
– When the searched concept [disease or intervention] has been
emerged since a certain year
– Periodical searching [per 5-10 years] to update a project depending on
grant, e.g. Burden of disease
– When you are searching to study the time trend of a topic
– Commissioner’s advises you to limit the search to a certain year
onward
– Searching for events-related searches for example war or natural
disasters
– If you need a stratified sample of publications during time periods [for
special needs]
• You should provide a good reason for limiting the search time
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40. Limitations in search and publication bias
• Publication type/status limitation
– Only journal papers?
– How about Grey literature?
• ClinicalTrials.gov and WHO ICTRP
• Dissertations
• Conference Proceedings
• There a good examples of change in conclusion of
systematic reviews including unpublished/grey
literature (e.g. Oseltamivir (Tamiflu))
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41. Limitations in search and publication bias
• Language bias: Only English
• Database bias: PubMed [Geographical and
Language Bias]
• Full Text Bias: Only free or open access papers
• Published Literature Bias
• Date/Time Limitation Bias
• All biases should be noticed and mentioned in
the systematic review
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42. Practice: Working with EndNote
• Tricks to be used
– Import/export the records
– Modifying import filters
– Modifying export filters
– Using DOI and PMID for updating records
– De-duplicating in a few clicks
– Full Text Finder
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43. Managing your search results
• Create an EndNote Library and name it
properly
• Import all three exported files one by one
using the related import filter and note the
number of search results per database and
total number of results
• De-duplication
– Check the default de-duplication fields in EndNote
– Use find duplicate to find, check and delete them
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44. Managing your search results
• De-duplication
– What causes de-duplication
– What are available methods for de-duplication
– Note the number of duplicates
– There are methods for de-duplication in search step!
• EMBASE let’s you to exclude ‘MEDLINE Journals’
• You can use ‘NOT MEDLINE[sb]’ at the end of your string to
exclude MEDLINE records in PubMed search
• There is an option in some of Ovid SP databases to remove
the duplicated
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45. Search Methods are Part of Research
Methods: Reproducible?
• Now you have:
– Search Date
– Search strategies per database
– Total number of search results and duplicates
• Could any other researcher repeat this search
using your search report and get the same
number of results?
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46. Screening via checking title/abstract
• Using EndNote for Screening
– Change of View
– Searching for Screening inside EndNote
• Using Highlighted Word Document
• Note the number of screened records
checking the title and abstract
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47. Getting the full texts of screened records
• EndNote feature
• Contacting the authors
• Using available online databases/services
• Inter-Library Loan
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48. Studification: Putting salami back together
• Putting separate reports of one study under
one study name
– Check PICO of two similar papers/reports
– Do not delete any relevant report
– Contact the authors to make sure they belong to
the same study
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49. Non-English literature
• Check title and abstract with your inclusion/exclusion criteria
• Use Google Translate
• Contact the authors of the paper
• Contacting the authors who have cited the non-English paper
• Finding volunteer/fee-based services to do the translation
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50. Categorization of Studies in Review
• Included Studies
• Excluded Studies
• Studies Awaiting Assessment: If you could not get
the full text or enough info to decide on
inclusion/exclusion; it will be mentioned in the
review in this section
• On-Going Studies: If the records and/or
contacting the researchers shows that the study
has not been finished yet, the study will be
mentioned in the review in this section
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51. Search team
(at least one librarian/information specialist)
AND
(at least one expert in the topic)
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52. From Search Protocol to Search Report
• Structure of the search report
• PRISMA Flow Diagram
– Use the Word Template in PRISMA Website
– Use Review Manager
– Use PRISMA Flow Diagram Generator
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53. Register you systematic review
• Go ‘Cochrane’!
• PROSPERO [Cochrane does it for you]
• Publish in Systematic Reviews journal
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54. Thanks for Your Attention
and
Question Me, Please!
• Feel free to contact me at
– farhadshokraneh [at] gmail.com
– farhad.shokraneh [at] nottingham.ac.uk
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