e3 - review of literature [dr a bermudez]

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Amiel Nazer C Bermudez, MD, MPH 1

Conduc'ng & Wri'ng the Review of Literature

Amiel Nazer C. Bermudez, MD, MPH Department of Epidemiology & BiostaDsDcs

College of Public Health University of the Philippines Manila

Learning ObjecDves

At the end of the session, parDcipants should be able to:

§  Enumerate the reasons for reviewing the literature

§  Enumerate the steps in conducDng a literature review

§ Conduct a focused literature search using MEDLINE

§  Fill out a literature matrix appropriately

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Literature

§ Refers to the broad spectrum of sources that are relevant to an inves'ga'on.

§ No longer limited to books or periodical, especially with the explosion of informaDon on the internet.

Reasons for reviewing the literature

§  Determine previous research on the topic

§  Determine the level of knowledge on the topic

§  Determine the relevance of current knowledge base to the problem area

§  Provide ra'onale for selecDon of research strategy

(DuPoy & Gitlin, 2011)

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Steps in conduc'ng a literature search

Step 1: Delimit what is searched

§  Involves seZng parameters as to what is relevant to search

§  Boundaries set must ensure a review that is comprehensive but s'll prac'cal and not overwhelming

§  No hard and fast rule on how to delimit the literature search but it always helps to refer to the research objec've

§  A pracDcal strategy is to base a search on the core concepts and constructs


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Delimit what is searched PEO

PopulaDon

Exposure

Outcome

Delimit what is searched PICOM

PopulaDon

IntervenDon (or Exposure)

Control

Outcome

Methods / Design

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Delimit what is searched Other strategies (and examples)

§  Date §  Last 5 years §  1990 onwards

§  Language §  English

§  Type §  Academic literature §  Newspaper arDcles §  Web blogs

§  Sources §  Academic databases §  Official websites

§  Country §  Developing countries §  Asian countries §  ASEAN countries

Delimit what is searched Developing the search strategy

§  List all possible related terms or synonyms.

§ Make use of Boolean operators.

OPERATOR RESULTS USES

AND Includes records that contain both the search terms

Narrows the focus of the search by including search terms

OR Includes records that contain either of the search terms or both

Expands the search; ensures that synonyms or related terms are included in the search

NOT Excludes records that contain the search term(s) it precedes

Narrows the focus of the search by excluding search terms

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Delimit what is searched Use of Boolean operators

“adult” OR “essenDal hypertension” OR “primary hypertension” OR “secondary hypertension”

4,389,594

“adult” OR “essenDal hypertension” OR “primary hypertension” NOT “secondary hypertension”

4,388,248

“adult” AND (“essenDal hypertension” OR “primary hypertension”) NOT “secondary hypertension”

10,851

Step 2: Perform a literature search

Where to search?

•  Card catalogues or online public access catalogues

•  Printed indices (e.g. Index Medicus)

•  Online databases (e.g. MEDLINE, OVID, HERDIN)

•  Bibliographies

•  RouDnely-‐collected data

•  Responses to inquiries about an ongoing research

(WHO – WPRO, 2001)

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UP Manila Web Online Public Access Catalogue h@p://lib.upm.edu.ph/index.php/webopac

Philippine Index Medicus h@p://pimedicus.upm.edu.ph/

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HERDIN h@p://www.herdin.ph/

OVID h@p://gateway.ovid.com

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MEDLINE h@p://www.ncbi.nlm.nih.gov/pubmed

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Searching the MEDLINE database IllustraGve example

§  Research objecDve §  To determine the associaDon between birth weight and adult hypertension

§  Delimit what is searched §  P = Adults §  E = Birth weight §  O = Hypertension

§  IdenDfy search terms §  Adults = “adults”, “adult” §  Birth weight = “birth weight”, “birth weight” §  Hypertension = “essenDal hypertension”, “primary hypertension”

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Step 3: Organize informaDon

§  Read abstracts (of journals) or table of content (of books) to determine the value of the source to the study

§  Classify the source according to relevance; may use the categories suggested by Findley

A Highly relevant Absolutely must be read

B Somewhat relevant Probably will be read depending on the direcDon taken

C Might be relevant May be read depending on the direcDon taken

X Not relevant Will not be read (but will be kept just in case)


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Step 3: Organize informaDon

§  Read through the sources and take notes; note-‐taking styles may vary from person to person but should include the following §  Complete bibliographic citaDon §  Conceptual framework §  Methodology §  Brief review of findings

§  A literature review matrix may help in organizing informaDon from sources (i.e. contents of the matrix may be customized based on the preferences of the researcher).

Sample literature review matrix

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Step 4: CriDcally evaluate the literature

§  Conceptual framework §  Are the aims clearly stated and research ques'ons clearly iden'fied?

§  Does the author link the work to an exis'ng body of knowledge?

§  Study design §  Are the methods appropriate and clearly described? §  Is the context of the study well set out? Did the research design account for possible bias?

§  Are the limita'ons of the study explicitly iden'fied?

(Jones, 2007)

Step 4: CriDcally evaluate the literature

§  Research analysis §  Are the results clearly described, valid and reliable? §  Is the analysis clearly described?

§  Conclusions §  Are all possible influences on the observed outcomes considered?

§  Are conclusions linked to the aims of the study? §  Are conclusions linked to analysis and interpreta'on of data?

(Jones, 2007)

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Checklist in evaluaDng research arDcles (1/4) (From DuPont & Gatlin, 2011)

§  Was the study clear, unambiguous, and internally consistent?

§  What is / are the research quesDons(s)? Are they clearly and adequately stated?

§  What is the purpose of the study?

§  How does the purpose influence the design and conclusion?

§  Describe the theory that guides the study and the conceptual framework for the project. Are they clearly presented and relevant to the study?

§  What are the key constructs idenDfied in the literature review?


§  What level of theory is suggested in the literature review? Is it consistent with the selected research strategy?

§  What is the raDonale for the design found in the literature review? Is it sound?

§  Does the design of the project fit the level of theory? Is the relevant knowledge presented in the literature review?

§  Diagram the design.

§  Does the design answer the research quesDon(s)? Why or why not?

§  What are the boundaries of the study? How are the boundaries selected?

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§  What efforts did the invesDgator make to ensure validity and reliability?

§  What data collecDon techniques were used? Is the raDonale for these techniques specified in the literature review and / or in the methods secDon?

§  How does data collecDon fit with the study purpose and study quesDon?

§  How are the data analyzed? Does the data analysis plan make sense for the study? How does the data analysis plan fit with the study purpose and study quesDon?

§  Are the conclusions supported by the study?


§  What are the strengths of the study?

§  What level of knowledge is generated?

§  What use dies this knowledge have for health and human service pracDce?

§  Are there ethical dilemmas presented in the arDcle? What are they? Did the author(s) resolve the dilemma in a reasonable and ethical manner?

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Step 5: Write the literature review

§  The literature review is not simple a regurgitaDon of who said what on a parDcular subject.

§  A successful review is an interpreta've piece of work that acknowledges what has come before, and how this can be built upon and expanded.

(Jones, 2007)

Some pointers in wriDng the literature review

§ Define key concepts to be used in the research, and how these will be used within the researcher’s own work.

§  In discussing the theoreDcal framework, jus'fy why a certain theory has been adopted, and spell out what research ques'ons are raised by this approach.

§ Discuss previous empirical work, methods adopted, and salient findings.

(Jones, 2007)

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Developing the argument

Where there is agreement and disagreement on parDcular issues:

“While there is general agreement that Z occurred [insert references], there has been some debate whether this is due to A [insert references] or B [insert references].”

(Jones, 2007)

IllustraDve Example Factors associated with Kawasaki Disease

In terms of climaGc factors, a study conducted in California revealed no associaGon between KD incidence and temperature or precipitaGon (Chang, 2002). However, Bronstein et al in 2000 revealed that KD incidence was inversely associated with average monthly temperature (r = -‐ 0.47, P < 0.001) and posiGvely associated with average monthly precipitaGon (r = -‐ 0.52, P < 0.001).

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On criDcisms that are leveled at parDcular studies:

“Bermudez’s findings have been criGcized because of A, B, C [insert references], but are, nonetheless, relevant in this research because it suggests X, Y, Z.”

(Jones, 2007)


Offering suggesDons of what can be surmised or understood from the literature:

“In summary, it is possible to suggest that A is related to B. However, what is sGll not known is how C fits in this relaGonship, which is the purpose of this research.”

(Jones, 2007)

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IllustraDve Example Factors associated with Kawasaki Disease

There have been studies that suggest the involvement of infecGous agents such as Parvovirus B19, Bocavirus, Cytomegalovirus or other viruses, Propionibacterium acnes, Ricke@siae, and Yersiniae in the development of KD (Skevaki, et al., 2011). KD simulates many infecGve exanthema of childhood and there are reports of preceding infecGon in some that lead to a consideraGon of an infecGous eGology. It is hypothesized that KD is a mul3factorial disease occurring in gene3cally predisposed children, precipitated by some bacterial super an3gens that results in host immune ac3va3on (Palit & Inamadar, 2009).

Referencing in a literature review

§  It is not necessary to quote or cite every reference retrieved, only those that are relevant to the research ques'on.

§  Correct aTribu'on is of utmost importance! §  Referencing style depends on preference or insDtuDonal requirements (e.g. Harvard, Oxford, APA)

§ May use free bibliographic / citaDon tools or sooware (e.g. EndNote, Zotero, built-‐in tools in MS Word)

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References

§  DePoy E & Gitlin L. (2011). IntroducDon to research: Understanding and applying mulDple strategies, 4th ediDon. Elsevier Mosby: St Louis, Missouri.

§ World Health OrganizaDon – Regional Office for the Western Pacific. (2001). Health research methodology: A guide for training in research methods, 2nd ediDon. World Health OrganizaDon – Regional Office for the Western Pacific: Manila.

§  Jones K. (2007).Doing a literature review in health. In Researching health: QualitaDve, quanDtaDve and mixed methods. Saks M & Allsop J (eds). Sage: London

Thank you J [email protected]

e3 - review of literature [dr a bermudez]

Documents

search terms

literature search step

focused literature search

amiel nazer c bermudez

literature review

search strategy list

essendal hypertension

primary hypertension