Literature Reviews for the Health Sciences

Robin FeatherstoneClinical Medicine Librarianrfeathe@uwo.ca

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.

Why would you have to conduct one?

• For your thesis• For your work as a research assistant• For a funding proposal or grant application• For your academic work as a faculty member• For your work as a professional researcher

7 tasks in the Research Lit Review

1. Selecting research questions2. Selecting your sources3. Choosing search terms4. Running your search5. Applying practical screening criteria6. Applying methodological screening criteria7. Synthesizing the results

Selecting research questions

Why do I need a research question?

• To guide your review• To provide you with keywords for your search• To give your research precision

Scenario

You’re applying for a grant to support your research on hypertension in patients with diabetes mellitus.

Think of some specific questions related to this topic...

QuestionsBroad:• What is the prevalence of hypertension in patients with

diabetes mellitus?

Narrow:• Does ambulatory BP readings improve detection rates for

hypertension in patients with type 1 diabetes mellitus?

Very Narrow:• What are the attitudes of general practitioners in Southern

Ontario to the use of ambulatory BP readings for patients with type 1 diabetes mellitus?

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

Good Question for Literature Review

Narrow:• Does ambulatory BP readings improve

detection rates for hypertension in patients with type 1 diabetes mellitus?

Selecting your sources

Lit reviews depend on data from seven sources

1. Online public bibliographic databases (i.e., MEDLINE)

2. Private bibliographic databases (i.e., EMBASE)3. Specialized bibliographic databases (i.e.,

Cochrane Database of Systematic Reviews)4. Manual or “hand searches” of references lists5. “Grey literature” -

http://www.slideshare.net/giustinid/libr534-class-vi-ib2

6. Web reports7. Experts

To find databases...

1. Try program pages from the library: www.lib.uwo.ca/programs/

2. Consult your librarian:www.lib.uwo.ca/contact/instruction

Selecting sources

Where are we likely to find articles that answer the question: Does ambulatory BP readings improve detection rates for hypertension in patients with type 1 diabetes mellitus?

Some places to search Bibliographic Databases• Medicine

– PubMed (or Ovid MEDLINE), EMBASE, Cochrane Library

• Multidisciplinary– Scopus– Web of Science

• Nursing and Allied Health– CINAHL

Websites• Associations, Organizations & Government

– WHO, American Diabetes Association, Canadian Diabetes Association, Health Canada, Public Health Agency Canada etc...

Other• “Grey Literature”

– ProQuest Dissertations & Theses, conference proceedings (i.e., AMA), etc...

Choosing search terms

Breaking down your question

1. Select your database2. Break you question into concepts3. Identify subject headings for each concept4. Identify keywords for each concept

• Tips: – Use a “target article” to help identify search terms– Use a concept map to keep track of your terms:

Why do I have to select a database first?

Your database will determine:1. Your subject headings2. Your operators (i.e., truncation symbols)

Different databases have different subject headings

• Tips:– Complete a concept map for each database that you search– Select subject headings that are the closest match for your concept

(remember: systematic, explicit and reproducible)– Pay attention to “explode” commands – some databases will search related

headings by default, others will not

Database Subject Headings

Medline MeSH

EMBASE EMTREE

CINAHL CINAHL Headings

Cochrane Library MeSH

Web of Science N/A

Scopus N/A

Identifying concepts

Which concepts are contained in the question: Does ambulatory BP readings improve detection rates for hypertension in patients with type 1 diabetes mellitus?

1.Hypertension2.Diabetes Mellitus, Type 13.Ambulatory blood pressure readings

Concept #1

Ovid MEDLINE search terms

Concept #2 Concept #3

Subject Headings

Keywords

AND AND

OR

Hypertension [MeSH]+ Diabetes Mellitus, Type 1 [MeSH]+ Blood Pressure Monitoring, Ambulatory [MeSH]

OR

OR

OR

OR

Hypertensi$.mp. (Diabetes mellitus adj5 (type 1 OR insulin?dependent OR juvenile?onset OR sudden?onset)).mp.

((blood pressure OR BP) adj2 (monitor$ OR test$) adj5 (home OR self OR ambulatory)).mp.

OR

((high OR elevated) adj2 (blood pressure OR BP)).mp.

Iddm.mp.

OR

OR

Some key operators in OvidOperator Command

$ Truncation (finds alternate endings)

? Wildcard (finds alternate spellings)

.mp. Mapping Alias (tells Ovid to search for your term in the Title, Abstract, Subject Headings, Table of Contents and Key Phrase Identifier fields) – useful for lit. reviews because it is broad

() Parentheses control the order of search operations

Adj Adjacency operator (can be followed by a number) tells Ovid terms must appear adjacent to one another

AND all terms must appear in results

OR any terms will appear in results

Note: These are recommended operators for research lit reviews. There are many, many more operators... Use Ovid‘s Help menu to locate them.

Running your search

Running your search(es)• Start with your first concept

– Search for the subject headings first– Then search keywords– 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

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

Please complete the following search in Ovid Medline

AND AND

OR

Hypertension [MeSH]+ Diabetes Mellitus, Type 1 [MeSH]+ Blood Pressure Monitoring, Ambulatory [MeSH]

OR

OR

Hypertensi$.mp. (Diabetes mellitus adj5 (type 1 OR insulin?dependent OR juvenile?onset OR sudden?onset)).mp.

((blood pressure OR BP) adj2 (monitor$ OR test$) adj5 (home OR self OR ambulatory)).mp.

OR

((high OR elevated) adj2 (blood pressure OR BP)).mp.

Iddm.mp.

Applying practical & methodological screening criteria

Screening

• Two kinds: practical and methodological • Why?

– Use practical screening to identify a broad range of potentially useful studies

– Use methodological screening to identify the best available studies

Practical Screening Criteria – some examples

1. Date of publication – only studies conducted between 2005 and 2010

2. Participants of subjects – only children 6 to 12 years of age

3. Publication language – only materials written in English

4. Research design – only clinical trials

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.

Applying Screens (or limits)

• Apply practical screens by using “limits” (may also be called “search options”)

• Apply methodological screens by reading through the articles

Apply Practical Screens

• Add the following limits to your combined search result set: – English Language– Publication Year: 2005 - Current

Next steps

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 a new concept map

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

Working with your results

• Export search results from each database or website into a citation manager (i.e., RefWorks)

• Remove duplicates• Remove inappropriate studies by applying

methodological screens

Synthesizing the results

Look for Patterns

• What conclusions did these studies reach? • Which studies agreed/disagreed with the

consensus?

• Consider using a synthesis matrix:www.ncsu.edu/tutorial_center/writespeak/download/Synthesis.pdf

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 findings4. Describe the quality of a body of research*

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

Recap• Remember... research lit review is: systematic, explicit and reproducible• Select appropriate research question• Identify appropriate databases• Break your question into concepts• Identify synonyms and subject headings for each concept • Combine synonym searches with OR • Combine concept searches with AND• Apply practical and methodological screens• Send search results to a citation manager• Remove duplicates• Use your lit review to summarize knowledge, assess research and

support new research initiatives

Questions

Robin FeatherstoneClinical Medicine Librarianrfeathe@uwo.ca