how to conduct a literature review (israpm 2014)

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Saeid Safari MD, Anesthesiologist Editorial Manager of Anesthesiology and Pain Medicine [email protected] How to Conduct a Literature Review Searching references in medical journalism ISRAPM 2014

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Page 1: How to Conduct a Literature Review  (ISRAPM 2014)

Saeid SafariMD, Anesthesiologist

Editorial Manager of Anesthesiology and Pain Medicine

[email protected]

How to Conduct a Literature ReviewSearching references in medical journalism

ISRAPM 2014

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Objectives List four categories of information resources

Apply selection criteria to identify appropriate

information resource

List five databases to find primary studies

Strategize and execute a systematic, explicit and

reproducible search of the biomedical literature

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Searching for scientific problemReview of literature

H y p o t h e s i sAims of research

M e t h o d s Plan of research

ResearchResults

Researchers work in graphic form

Aztec Pyramide

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What’s a Research Lit Review?

A research literature review is a systematic, explicit and

reproducible method for identifying, evaluating, and synthesizing

the existing body of completed and recorded work produced by

researchers, scholars, and practitioners.*

*Fink, A. (2005). Conducting Research Literature Reviews. London: Sage.

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Level of Evidence Pyramid

Qualitative Studies

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Criteria for Selecting a Resource1. Soundness of evidence-based approach

2. Comprehensiveness and specificity

3. Ease of use

4. Availability

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Questions to Ask Bias? Conflict of interest?

Evidence grading or ranking applied?

Links?

Discipline coverage?

Consistent and quick to search?

Cost?

Available in my location?

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HOW TO SEARCH STUDIES

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A Comprehensive Search is... Systematic

Explicit

Reproducible

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7 tasks in the Research Lit Review

1. Selecting research questions

2. Selecting your sources

3. Choosing search terms

4. Running your search

5. Applying practical screening criteria

6. Applying methodological screening criteria

7. Synthesizing the results

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SELECTING RESEARCH QUESTIONS

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Why do you need a research question?

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Scenario

You’re applying for a grant to support your research on

management of patients with atrial fibrillation.

Think of a question related to this topic...

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Possible questionsBroad:

What is the prevalence of atrial fibrillation?

Narrow:

What costs are associated with hospitalization for atrial fibrillation?

Very Narrow:

What strategies have been utilized in Iran to reduce length of stay for

patients with atrial fibrillation?

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How questions influence search results

Relevancy

Retrieval(# of search results)

Broad Questions

Narrow Questions

High = lots of articles

Low = very few articles

High = directly relevant articles

Low = mostly irrelevant articles

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Sample Search Statements I am looking for articles about osteoarthritis of the knee.

13,886 articles in PubMed

I am looking for RCTs on arthroscopic surgery for osteoarthritis

of the knee that include placebo surgery as a control. 9 articles in PubMed

I am looking for RCTs on arthroscopic surgery conducted in

latino females with type 1 diabetes mellitus. 0 articles in PubMed

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Stage In Searching1. Define search topics

2. Choose appropriate search terms/keywords that represent the

topic

3. Decide where to search/which sources to use (e.g. library

catalog, online databases)

4. Develop search strategy by optimizing search tools

5. Observe search results

6. Revise the search as necessary

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Turn your statement into a strategy

1. Break you question into concepts

2. Identify subject headings for each concept

3. Identify keywords for each concept

Tips: Use a “target article” to help identify search terms

Use a strategy worksheet to keep track of your terms:

http://www.lib.uwo.ca/files/taylor/grad/Search_Strategy_Worksheet.pdf

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Does hand washing prevent MRSA? in the ICU?

Hand washing MRSA ICU Prevention

Handwashing [MeSH]

Methicillin-Resistant Staphylococcus aureus [MeSH]

Intensive care units [MeSH] +

Handwash$.mp. Methicillin resistant staphylococcus aureus.mp.

Intensive care unit$.mp.

Prevent$.mp.

Hand wash.mp. MRSA.mp. ICU.mp.

Hand disinfect.mp. Critical care unit$.mp.

Surgical scrub$.mp.

Hand clean$.mp.

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SELECTING YOUR SOURCES

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Lit reviews depend on data from seven sources

1. Online public bibliographic databases

2. Commercial bibliographic databases

3. Specialized bibliographic databases

4. Manual or “hand searches” of references lists

5. “Grey literature”

6. Web reports

7. Expert opinions

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Where to search Bibliographic Databases

Medicine PubMed (or Ovid MEDLINE), EMBASE, Cochrane Library, PsycINFO

Multidisciplinary Scopus

Web of Science

Nursing and Allied Health CINAHL

Websites

Associations, Organizations & Government World Health Organization, Health Canada, Canadian Medical Association, etc.

Other

“Grey Literature” Dissertations & Theses, SCOPUS (conference proceedings), Web search engines

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CHOOSING SEARCH TERMS

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Different databases have different subject headings

Tips:

Select subject headings that are the closest match for your concept

Pay attention to “explode” commands – some databases will search related

headings by default, others will not

Database Subject HeadingsMedline MeSH

EMBASE EMTREE

CINAHL CINAHL Headings

Cochrane Library MeSH

PsycINFO Thesaurus of Psychological Index Terms

Scopus, Web of Science N/A

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Which term explodes?

A. Bird Diseases B. Neutropenia

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Identifying concepts & MeSH headings

Which concepts are contained in the question:

Does hydration decrease incidence of delirium

at the end of life?

Find the MeSH heading(s) for each concept & add them to your worksheet

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AND AND

OR exp Fluid Therapy/ Delirium/ exp Terminal Care/

OR Palliative Care/

exp Terminally Ill/

OR

OR

OR

Concept #1

Ovid MEDLINE strategy

Concept #2 Concept #3

Subject Headings

TextWords

Blank worksheets: http://muhclibraries.mcgill.ca/SearchStrategyWorksheet.doc

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Key Operators in OvidOperator Command Example

* Find alternate endings to this word

nurs* [will find nurse, nursing, nurses]

.tw. Search for this term in the Title and Abstract fields

anxiety.tw.

adj Search for one term within x number of terms from another

patient adj3 anxiety [will find patient within three words of anxiety]

AND Find articles where both terms appear

smoking AND cessation

OR Find articles where either term appears

smoking OR tobacco

Page 31: How to Conduct a Literature Review  (ISRAPM 2014)

AND AND

OR exp Fluid Therapy/ Delirium/ exp Terminal Care/

OR Palliative Care/

exp Terminally Ill/

OR

hydrat*.tw. deliri*.tw. (terminal* adj4 patient*).tw.

OR

fluid*.tw. palliative.tw.

ORwater.tw. end of life.tw.

Concept #1

Ovid MEDLINE strategy

Concept #2 Concept #3

Subject Headings

TextWords

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RUNNING YOUR SEARCH

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Running your search(es) Start with your first concept

Search for the subject headings first

Then search text words

Combine these synonymous searches with OR using your

search history

Repeat for your second, third, and subsequent concepts

Finally, combine large search results set with AND

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Running your search(es)

Search #2 =

Search #3 =

Search #4 =

Search #5 = #1 OR #2 OR #3 OR #4

Search #1 =

Concept 1

Search #6 =

Search #7 =

Search #8 =

Search #9 =

Concept 2

Search #10 = #6 OR #7 OR #8 OR #9

Search #11 = #5 AND #10

Results

Page 35: How to Conduct a Literature Review  (ISRAPM 2014)

Please complete the following search in Ovid Medline

AND AND

OR exp Fluid Therapy/ Delirium/ exp Terminal Care/

OR Palliative Care/

exp Terminally Ill/

OR

hydrat*.tw. deliri*.tw. (terminal* adj4 patient*).tw.

OR

fluid*.tw. palliative.tw.

ORwater.tw. end of life.tw.

Concept #1 Concept #2 Concept #3

Subject Headings

Text Words

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APPLYING PRACTICAL SCREENING CRITERIA

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Screening Two kinds: practical and methodological

Use practical screening to identify a broad range of

potentially useful studies

Use methodological screening to identify the best available

studies

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Practical Screening Criteria –examples

1. Date of publication

only studies conducted between 2005 and 2010

2. Participants or subjects

only children 6 to 12 years of age

3. Publication language

only materials written in English or French

4. Research design

only clinical trials

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Apply Practical Screens Add the following screens (limits) to your combined search

result set:

English Language

Publication Year: 2001 – Current

Humans

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LIMITS/FILTERS• Most databases offer limit functions to help users limit

search results that are too broad or too many

• Limits are commonly specified according to:

- date of publication

- type of publications (books, journals, news, etc)

- age group

- language

- sex (male/female)

- type of files

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NEXT STEPS

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Working with your results Save or export search results into a citation manager (i.e.,

Endnote)

Remove duplicates

Remove inappropriate studies by applying methodological

screens

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Methodological Screening Criteria - some questions to ask

Is the study’s research design internally & externally valid?

Are the data sources used in the study reliable & valid?

Are the analytic methods appropriate?

Are the results meaningful in practical & statistical terms?*

*Fink, A. (2005). Conducting Research Literature Reviews. London: Sage.

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Moving to another source Retain as much of your original strategy as possible

Recognize that subject headings will be different (or non-

existent)

Keep track of your search terms using new worksheets

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Hand searching and final steps Locate the reference lists for selected articles*

Identify new articles that have cited your articles*

Identify key journals and “hand search” their issues

Test your search strategy by checking to see if a few “target

articles” appear in the results

* Use Web of Science or Scopus

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SYNTHESIZING THE RESULTS

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Use your results to...1. Describe current knowledge about your research topic

2. Support the need for and significance of new research

3. Explain research findings

4. Describe the quality of a body of research*

*Fink, A. (2005). Conducting Research Literature Reviews. London: Sage.

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Tips For Effective Searches1. Plan your search – identify the words that represent the topic of

your search

2. Avoid using too broad or general terms, use specific terms instead

to get limited but relevant results.

3. Use limit/filter functions as necessary

4. Create an account. Most online databases allow you to sign up for

an account/personal folder in their database that helps you manage

searches, search results or references, set up preferences, alerts,

and many others.

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Research strategy guide for finding quality, credible sources

1. Get organized

2. Articulate your topic

3. Locate background information

4. Identify your information needs

5. List keywords and concepts for search engines and databases

6. Consider the scope of your topic

7. Conduct your searches

8. Evaluate the information sources you found

9. Analyze and adjust your research strategy

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• Basic computer skill: More than

• Windows

• Word

• PowerPoint

• Excel

• SPSS

• Adobe photoshop

• Medline search

• Endnote

Basic skills for a scientist

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• Paper reading

• Critically and actively

• Ability to recognize problems in the

experimental design

• Ability to recognize key sentences

Basic skills for a scientist

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• Understanding and use of the literature

• Ability to evaluate a paper critically and accurately

• Familiarity to a broad-based, relevant and current literature

• Ability to generate useful notes while reading the literature

• Ability to generate interesting and important questions

• Ability to generate original ideas on the literature

Basic skills for a scientist

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• Experimental design

• Ability to get techniques to work predictably and reproducibly

• Ability to generate high quality data with both positive and negative controls that

can give clear cut answer to a question

• Ability to find the best available information from the best sources

• Ability to interpret fully your data, generate next question or hypothesis and

design the next experiment

• Ability to troubleshoot and solve a technical problem

• Resistance to doing an incomplete experiment using whatever reagents or cells

that happen to be available ”to see what happens”

Basic skills for a scientist

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• Paper writing

• Ability to group data in a logical fashion into good figures

• Ability to make a good-looking figure

• Ability to interpret data in relation to existing literature and

come up with new ideas

• Ability to write a good and useful first draft

• Ability to use key sentence

Basic skills for a scientist

Page 55: How to Conduct a Literature Review  (ISRAPM 2014)

Scholar Google

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Results in scholar Google

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Google Scholar Profile

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TUMS Digital Library

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All EBM Reviews (OVID)

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Cochrane Library

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Drug Information Full Text

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Scopus

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UpToDate

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ULRICHS WEB

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MD Consult

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ScienceDirect

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Emerald Insight

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Iran Medex

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JAMA

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Wiley Online Library

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MagIran

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MEDLIB

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Springer Link

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Theime

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PubMed

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MeSH (Medical Subject Headings)

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MeSH Subheadings

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MeSH

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Result, PMID, Related Articles!

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Useful Sites CADTH. Grey Matters: a practical search tool for

evidence-based medicine -

http://cadth.ca/en/resources/grey-matters

Cochrane Handbook for Systematic Reviews and

Interventions - http://www.cochrane-handbook.org/

IOM (Institute of Medicine). Finding what works in health

care: standards for systematic reviews -

http://www.iom.edu/Reports/2011/Finding-What-Works-in-Health-Care-Standards-for-Systematic-Reviews.aspx

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Recap

How would you describe a quality literature review?

Synonymous searches are combined with ___

Can you apply methodological screens with a database?

Finally, please make your librarian happy by filling out your

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EFFECTIVE MEDICAL LITERATURE SEARCHING

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Objectives

1. Formulate your question2. Understand basic database structure3. Use of Boolean Logic4. Use Field Searching5. Use of Controlled Vocabulary6. Specialty techniques (truncation, etc.)7. Building your search strategy

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Reasons for Searching the Medical Literature

To answer a specific patient case-related question (clinical practice)

To learn more about a medical topic (education)

To determine current best practice (guideline)

To give the best possible care to patients using evidence-based medicine

Page 88: How to Conduct a Literature Review  (ISRAPM 2014)

Information OverloadPubMed

(Medline) contains over 18 million journal citations going back to ~1950

Year # new citations added*

2005 606,0002006 623,089 2007 670,943 2008 671,904

*statistics from http://www.nlm.nih.gov/bsd/bsd_key.html

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Asking the Question: PICO Patient, Population or Problem

What are the characteristics of the patient or population?

What is the condition or disease you are interested in? Intervention or exposure

What do you want to do with this patient (e.g. treat, diagnose, observe)?

Comparison What is the alternative to the intervention (e.g.

placebo, different drug, surgery)? Outcome

What are the relevant outcomes (e.g. morbidity, death, complications)?

http://healthlinks.washington.edu/ebp/pico.html

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Parsing the Question What are the main concepts in your

question?Sample question:

Does nutrition therapy improve decubitus (pressure) ulcer healing in an elderly patient?

Concepts:

Nutrition therapy

Decubitus/pressure ulcers

Ulcer healing Elderly patientsTreatment efficacy

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A database is an organized collection of data.

Bibliographic databases are searched through many of the same techniques as any other database

Focus will be on PubMed, but these techniques apply to ANY literature database

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Examples of Records and FieldsRecord #

Author Title Publisher Date of Publication

1 Jones KM Infectious Diseases

Wiley 2001

2 Smith BR Medicine Cambridge Univ. Press

2004

3 Johnson AS

Cancer Elsevier 2005

4 Bradley PL

Asthma Synergy 2003

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Examples of Records and FieldsRecord #

Author Title Publisher Date of Publication

1 Jones KM Infectious Diseases

Wiley 2001

2 Smith BR Medicine Cambridge Univ. Press

2004

3 Johnson AS

Cancer Elsevier 2005

4 Bradley PL

Asthma Synergy 2003

RED=RECORD BLUE=FIELD PURPLE = ONE PIECE OF DATA

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Searching a DatabaseDifferent search interfaces do the same things in slightly different

ways

Good search interfaces should provide Ability to search for a specific item Ability to search for related items to a

known item Ability to search in a specific field or fields Ability to combine search terms using

Boolean Logic Ability to retrieve search results in a useful

way

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Boolean LogicA British mathematician named George

Boole (1815-1864) developed an algebraic system of logic that is now widely used in computer and electronic systems including database searching.

While Boole’s algebraic system can be complex, a very simple form of Boolean Logic is used for searching most bibliographic databases.

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Boolean OperatorsStandard Boolean Logic for database

searching uses 3 relationships among search terms.

ANDOR NOT

It is both simple and powerful.

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AND

BOTH terms included in any results.

If a record has only one of the two terms, it will not be retrieved.

If the record has neither term, it will not be retrieved.

What does this do to the amount of records retrieved?

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OROnly one (NOT both)

of the terms are in the results

‘OR’ will retrieve the record if both are included.

What does OR do to the amount of records retrieved?

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NOTExcludes any

results containing the term

Records containing both will not be retrieved.

What does NOT do to the amount of records retrieved?

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Using OR“OR” groupings contain terms for the same

idea/concept and are usually put in parenthesis

(term OR term OR term) where all terms are difference ways of

representing the same concept

(faculty OR teachers OR professors)

(students OR learners OR pupils)

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Using AND“AND” groupings contain terms for different

ideas/concepts and can combine OR groupings

Term AND (Term OR Term) where each represents a different concept

heart attack AND smoking

Diabetes AND exercise

Cancer AND (treatment OR therapy)

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Using NOT“NOT” statements are usually put last and

can contain an “OR” grouping; they are often used to get rid of a common subgroup

Students NOT dental

Diabetes NOT juvenile

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Putting Them Together1. Identify the concepts (Parse the

question)2. List specific terms for each concept3. Put the terms for each concept in an

OR statements within parentheses4. Combine OR statements with AND5. Add any NOT statements to the end

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Creating a Boolean Search

Concept 1Influenza

Concept 2Vitamin C

Concept 3Treatment

Concept 4helpfulness

Influenza Vitamin C Treatment OutcomeFlu Ascorbic acid Therapy Recovery

Orange Juice Management Success

QUESTION: Is Vitamin C helpful in treating the flu?1. Identify concepts and list terms

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Step 22. Make your OR statements, one per

concept (influenza OR flu OR orthomyxovirus) (vitamin C OR ascorbic acid OR

ascorbate) (treatment OR therapy OR management) (outcome OR recovery OR success)

Page 106: How to Conduct a Literature Review  (ISRAPM 2014)

Steps 3 and 4 3. Put “AND” between each of the OR

statements(influenza OR flu) AND (vitamin C OR

ascorbic acid OR orange juice) AND (treatment OR therapy OR management) AND (outcome OR recovery OR success)

4. Consider any NOT statements you might want to add.

Note: NOT isn’t used very often

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Parsing a Boolean Search(emergency OR acute OR critical) AND

(treatment OR therapy OR management OR care) AND (motor vehicle accident OR car crash) NOT (pedestrian OR walking)

What are the four concepts?What terms are used for each concept?Which three concepts must be included in all

records found?Which concept must not be included in any record

found?

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Beyond Basic Boolean Field Searching Controlled Vocabulary

Subject vs. Keyword Searching Specialty Features

Truncation Phrase searching

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Field SearchingAlmost all databases will provide you with

some ability to search a specific field or fields.

Allows faster searching Allows more accurate searching

Not all databases may make all fields searchable.

Each search system will require a specific format.

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All Field vs. Specific Field Searches

I would like to find articles by John Smith.

Search all fields: John Smith Search Author Field only: John Smith

I would like to find an article published in 1997.

Search all fields: 1997 Search Publication Date Field: 1997

Why waste time searching for a date in the author field or an author in the volume field?

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Formats for Field SearchingDifferent databases provide different

formats for specifying fields.

Most use field names or nicknames Field ‘tags’ OR ‘labels’which may follow a period or be placed in

brackets or parentheses.

Some databases offer forms or drop-down menus.

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PubMedField tags go in [] and follow termField tags can be used within Boolean

queries

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PubMed Field Tagshttp://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=helppubmed.section.pubmedhelp.Search_Field_Descrip

[au] = author[ti] = title[tw] = textword[tiab] = title and abstract[mh] = medical subject heading

[dp] = date of publication[la] = language[gr] = grant number[ta] = journal name[ad] = affiliation

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OVID databases require field tags to follow the term separated by a period.

Meharry.in and 2005.yr

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Some databases, such as the ISI’s Web of Science (Science Citation Index Expanded) provide forms to fill out.

Select Field from drop-down menu

Select Boolean Operator

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Combining Field SearchesMultiple field searches can be combined

using Boolean logic.

Find a 2005 article by an author named Hubble about ankle fractures.

Combine with AND: 2005 in date/year field Hubble in author field Ankle fractures in title field

2005[dp] AND Hubble[au] AND ankle fractures[ti]

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Final Notes on Fields Each database provides its own specific

fields Each database requires a specific format

to designate field searching When searching a new database, take a

moment to read the help documentation; most will provide a list of fields and how to search them.

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Controlled VocabularyA controlled vocabulary is a set of

established terms where every term represents a single concept only one term is used for that concept

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Another example How many words could you think of for

the idea of “cancer”? Cancer, tumor, malignancy, neoplasm,

sarcoma…

Articles in a database Article one: “Breast tumors in young women” Article two: “Surgery for prostrate cancer.” Article three: “Diagnosing Melanoma.”

All three articles are about types of cancer but different terms are used in titles.

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In a controlled vocabulary ONE word (i.e., cancer) is chosen and placed in a special field, usually called a subject field.

For all three articles Article one: “Breast tumors in young women” Article two: “Surgery for prostrate cancer.” Article three: “Diagnosing Melanoma.”

The subject term (concept term) “cancer” is placed in the subject field by database indexers.

Now, Searching the database for cancer in the subject field will identify all records about the concept of cancer even if a different word for cancer is used.

Search ‘cancer-in-subject-field’ finds all three articles

How many articles would the search ‘cancer-in-title-field’ find?

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Structure of Controlled Vocabulary

Broader Concepts

Narrower Concepts

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More on Controlled Vocabulary “Expanding” = Search includes all

narrower terms beneath the searched term Some databases do it automatically, others

don’t “Focusing” or “Majoring” = For a given

item, some subject terms are considered the major focus; you can select to return only those articles. Hip fracture[majr] = only give me articles

where hip fracture is an important concept

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Subject vs. Keyword Searching

Controlled vocabulary searching

Matches terms against a

specific field in the record.

You need to consult a thesaurus (paper or online) to find out what the controlled vocabulary term is for each concept.

Free-text (keyword) searching

Some concepts have many synonyms. A free-text search statement would mean "OR"ing all those terms together

Matches terms against words anywhere in record (abstract, title, etc.).

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Advantages to Controlled Vocabularies Using the controlled vocabulary can make your

search more precise and easier. Increases the relevancy of results (fewer false

drops) The indexers have already done much of the

work for you. Searchable tree structures of terms can help you

find new terms to use.

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Problems with Controlled Vocabularies

NOT all databases use a controlled vocabulary

New concepts take time to be added There is often a lag phase during which the

newest articles aren’t indexed Controlled vocabularies can contain some

very strange things and some concepts may not be handled well

The controlled vocabulary must be easily searchable

Trying to understand what is and isn’t in a particular controlled vocabulary can give you a big headache!

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Combining Subject and Keyword Searching

To be comprehensive, it is often helpful to combine subject and keyword searching

(diabetes mellitus[mh] OR diabetes[tw])

(sickle cell anemia[mh] OR sickle cell anaemia[ti])

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Don’t forget… Boolean logic to combine terms Use of other search fields in combination

with subject terms

A Complex Search:(head[mh] OR head[tw]) AND (wound and

injuries[mh] OR trauma[ti] OR injury[ti]) AND 2005[dp] AND English[la]

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Some Specialty Features Truncation Phrase searching Neighboring and other rarer Boolean

operators

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TruncationWhat about including the singular and plural versions

of words as well as other word variations?For example: therapy, therapies, therapeutics,

You could combine them all in an OR relationship:

(therapy OR therapies OR therapeutics OR therapeutic)

But an easier way is by the use of truncation. therap*

Each database handles truncation in a unique way. The ‘*’ and ‘$’ are the most common wildcard symbols.

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More on TruncationSome examples:

Bacter$Proc*Vir?Staph?

Be cautious when truncating!

If the word stem is too short, there may be too many possible variations and you might pick up unrelated terms.

For example, using proc* for finding procaine-like drugs will also include words like proceedings and process.

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Phrase Searching Sometimes you want to force the

database to search for a set of words in exact order

“fever of unknown origin”

Most databases will accept a phrase in quotes.

BUT…some do not handle phrases well and will automatically break them up – usually ‘AND’-ing the terms

Check how the database handles phrase searching before doing it!

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Limits Options Many databases provide “limits” pages

that make it easier for you to select common options such as language, article type, publication dates, human or animal, gender, age groups, etc.

Each database’s limits options are unique

Most limits can be done ‘by hand’ using field tags, but sometimes limit pages save time

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PubMed Limits Page

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Step-By-Step Search Construction1. State the question 2. Identify the concepts in the question3. For each concept, determine keywords and

subject terms4. Specify field tags after terms if needed5. Combine terms for the same concept with “OR”

in parenthesis6. Combine “OR” statements with AND7. Put any NOT terms at the end

Keep track of your searches, how many articles were found total, and how many you selected as relevant

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Example Question: What is the appropriate ED

medical management of adult patients with intracranial hemorrhage (either trauma or spontaneous)?