Literature Reviews

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Bronfort, G., W. Assendelft, et al. (2001).
Efficacy of spinal manipulation for chronic
headache A systematic review. JMPT 24(7)
457-466.
Davis, C.G. (1998) Rear-end impacts vehicle and
occupant response. JMPT, 21(9) 629-39.
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Literature Reviews

• Another Descriptive Design
• (Along with case reports, surveys,
• and case series)

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DESCRIPTIVE DESIGNS
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The Literature Review

• Summarizes all available literature on a topic to
  produce a single paper
• Imperative to carry out in an objective and
  critical format
• Can cover a broad issue or a very focused
  clinical question
• Example I Cervical manipulation of whiplash
  patients
• Example II Cervical manipulation of whiplash
  patients with signs of VBI

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Literature Review

• A great deal of information is brought together
  and written so the reader can clearly understand
  the topic
• Literature reviews provide a new conclusion to
  the literature . . . a synthesis
• Not just rehashing all the articles involved

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Purpose

• Objectively report current knowledge concerning a
  certain topic based upon previously published
  research
• Provide a comprehensive overview of the topic
• Place information into perspective
• Find out what others have to say

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Reasons to Read Literature Reviews

• Save time when searching for information about
  patient care
• The author of the literature review has already
  done most of the work
• Provide information for decision makers
• Researchers use them to develop hypotheses and to
  identify pitfalls in previous research

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Literature Reviews

• May offer more conclusive results than a single
  primary research study
• Reviewing all studies on a topic tends to
  neutralize the extremes
• May provide a very high level of evidence
• Meta-analyses
• However, readers must consider the possibility of
  author bias

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Three Classifications

• Narrative review
• A comprehensive narrative synthesis of previously
  published information
• Qualitative systematic review
• A detailed search of the literature based upon a
  focused question
• Employs detailed, rigorous and explicit search
  methods

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Three Classifications Cont.

• Quantitative systematic review
• Evaluates each reviewed paper and statistically
  combines the results of the studies

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From JMPT Instructions for Authors

• Literature reviews
• Critical assessments of current knowledge of a
  particular subject of interest
• With emphasis on better correlation
• The pointing up of ambiguities
• And the delineation of areas that may constitute
  hypotheses for further study
• Meta-analysis is included

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Narrative Literature Review

• Three types
• Editorials
• Are typically written by the journals editor or
  an invited guest
• Commentaries
• Typically express an opinion (biased)
• Overview articles
• A narrative review that draws upon the wisdom of
  the commentator (biased)
• AKA unsystematic narrative reviews

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Why Narrative Literature Reviews?

• Usually more up to date than textbooks
• However, probably published 2 years after the
  research was done
• Presents a broad perspective on a given topic
• Practitioners can obtain up to date clinical
  protocols
• Often specific authors are solicited to write
  narrative overviews who are experts
• Many times they have conducted related research

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Systematic Methods Required

• Methods used in creating the paper should be
  revealed
• Inclusion/exclusion criteria explained
• Language, timeframe, specific type of tx.
• The list of sources used to locate literature
  should be complete
• Regarding chiropractic Not just PubMed
• Should include MANTIS, CINAHL, ICL, and others

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Narrative Overviews - Evidence

• One of the weakest forms of evidence for making
  clinical decisions
• They deal with broader issues than focused
  clinical problems
• They are potentially more biased
• Which is why they are one of the weakest

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Qualitative Systematic Literature Review

• AKA systematic review
• Detailed, rigorous and explicit methods are
  utilized
• Methodology is described step-by-step
• Noted for having a focused question or purpose
• All original (primary) research studies published
  on the topic are included

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Systematic Review Searching

• Multiple databases should be searched
• Also hand searches
• Should contact authors of previously published
  research
• Attempt to locate articles that may not have been
  published
• Failed studies

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Systematic Reviewing Process

• Papers are reviewed systematically and
  consistently
• Apply the same criteria to each one reviewed
• Several independent reviewers are typically
  involved
• Papers are rated using a scoring system
• Checklists are typically involved
• Then individual studies are integrated

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Systematic Review - Evidence

• More powerful evidence-based source of clinical
  information than narrative reviews
• Better-quality evidence than
• Case reports and case series
• Even better than poorly conducted RCTs

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Quantitative Systematic Literature Review

• Commonly known as a meta-analysis
• A systematic review that not only critically
  evaluates each paper, but also statistically
  combines the results of the studies
• Are very methodological like qualitative
  systematic reviews

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Meta-analyses Major Benefit

• Pooling of data between studies
• All of the original patient data from the studies
  under review are pooled
• Creates a larger sample size for statistical
  testing
• Increases power of the individual studies
• However, it is often difficult to find studies
  that are similar enough to pool data

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Meta-analyses - Evidence

• Considered a very high form of evidence for
  making clinical decisions
• More generalizable conclusions are possible
• More power
• Tends to even out extreme values through a
  process of averaging

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Writing a Narrative Review of the Literature

• Select topic that you are very interested in
• Need to have momentum to finish
• Select topic with a feasible focus
• Headaches would be impossible too broad
• Better chiropractic management of muscle
  tension headaches more focused
• Get help from experienced (published) colleagues
  or faculty
• Possibly offer co-authorship in return

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Step One

• Perform a preliminary literature search
• This applies for any research endeavor
• To see what has already been published on the
  topic
• There may already be a review published about the
  topic
• However, may still be able to get a review
  published using a different perspective

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General Guidelines

• Use the required writing elements for a narrative
  review
• Be well structured
• Synthesize the available evidence
• Convey a clear message
• Use an objective and scientific approach
• Follow the Uniform Requirements for Manuscripts
  Submitted to Biomedical Journals formatting
  guidelines

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Guidelines Cont.

• The necessary elements of a narrative review are
  similar to those required of any form of
  scholarly article
• Standard anatomy
• Title, Structured Abstract, Introduction, Method,
  Results, Discussion, Acknowledgements,
  References, Tables, Figures, and Figure captions

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Title

• Clearly describe the topic being reviewed
• May include the words literature review or
  review of the literature
• Example from JMPT
• Alcohol and low-back pain A systematic
  literature review

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Structured Abstract

• Objective Author should clearly state the
  purpose of the paper
• Background A description of what prompted the
  review or why it was written. Presentation of a
  context for the review.
• Methods Brief description of the methods used
  for the review.

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Structured Abstract Cont.

• Discussion Description of what information the
  review presents to the reader.
• Conclusion Summary of what the review
  contributes to the literature. What new
  conclusion can be drawn as a result of the
  synthesis of the literature.

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Key Words

• Use medical subheadings (MeSH) when possible
• Additional words that may be unique to this topic

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Introduction

• State the research purpose or focus
• Convince readers of the need or importance of the
  study
• Hasnt been reported previously
• Inadequately reported
• Incorrectly reported
• Define any unusual terms that are used

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Methods

• A step-by-step description of how the study was
  carried out
• List databases that were searched
• Typically must search at least two applicable
  databases in order to obtain a reasonable breadth
  and depth on a topic
• Articles harvested from reference sections
• Other sources for references
• Conference proceedings, communications with
  authors, books, etc.

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Describing Information Sources

• Name the database that was searched
• List search terms
• Define an inclusion timeframe
• Provide a starting year and an ending year and
  month
• Example
• A MEDLINE search was carried out using the terms
  neck pain and manipulation from 1966 through
  March, 2004.

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Parameters For The Literature Search

• Inclusion and exclusion criteria must be
  established to focus the search
• For example, exclude surgery related studies or
  drug trials
• Use Limits in PubMed and Advanced Search in
  MANTIS
• Choose language, date, discipline, etc.
• Search strategy should be described so another
  reviewer could duplicate results

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Results

• This section presents the outcome of the search
  process
• The number of articles that were retrieved
• How many of the articles were excluded from the
  review
• Which of the inclusion criteria they failed to
  meet

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Discussion

• The synthesis is the most demanding element of a
  narrative review
• All of the information retrieved in the
  literature search is combined into comprehensive
  paragraphs
• Notes must be kept for each study reviewed
  including the following information
• The purpose of the study being reviewed

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Discussion cont.

• A synopsis of the content
• The research design or methods used in the study
• A brief review of the findings

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Most reviews have a table of articles that were
utilized
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Synthesis

• The synthesis is the heart of the narrative
  review design
• Consequently it is important to ensure that a
  meaningful integration is accomplished
• Based on the literature reviewed, the author
  should offer an interpretation
• Also a critical appraisal of the papers reviewed
  may be in order

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Appendix A

• Check sheets or guides are helpful when
  critically appraising the articles
• Green BN, Johnson CD, Adams A. Writing Narrative
  Literature Reviews for Peer-reviewed Journals
  Secrets of the Trade. J Sports Chiropr Rehabil
  200115(1)
• 1 Absent, 2 Present but not complete, 3
  Present and complete

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Initial Impression

• Does the review appear to be relevant to an issue
  of interest?
• Dont waste your time reading articles that
  arent relevant or interesting There are plenty
  available that are relevant

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Abstract

• Is the specific purpose of the review stated?
• Is context for the overview provided?
• Is the type of research design stated?
• Are the search methods clearly summarized?
• Are the important findings clearly discussed?
• Are the major conclusions and recommendations
  clearly outlined?

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Introduction

• Is the specific purpose of the review clearly
  stated based upon a brief review of the
  literature?
• Is the need/importance and context of this study
  established?
• Are novel terms defined?

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Methods

• Were the electronic databases used to conduct the
  literature searches identified (MEDLINE, CINAHL,
  etc.)?
• Were the search years stated?
• Were the search terms stated?
• Were standard terms used as search terms,
  including Medical Subject Headings?
• Were the guidelines for including and excluding
  articles in the literature review clearly
  identified?

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Results - Discussion

• Were the results summarized in a comprehensible
  manner?
• Was the critical appraisal of each study the same
  and reproducible?
• Was the quality of the included articles assessed
  objectively?
• Was the variation in the findings of the studies
  critically analyzed?

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Discussion Cont.

• Was the meaning of the results addressed?
• Do the authors tie in the results of the study
  with previous research in a meaningful manner?
• Were the weak points and untoward events that
  occurred during the course of the study addressed
  by the authors?

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Conclusions

• Was a clear summary of pertinent findings
  provided?
• Were the authors conclusions supported by the
  evidence provided?
• Were specific directives for new research
  initiatives proposed?
• Specific implications to the practice environment
  are addressed?

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References

• Are references relevant, current and appropriate
  in number?
• Are all papers reviewed cited in the references?

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Overall Impressions

• Do the merits of this review of the literature
  outweigh the flaws?
• Were the authors unbiased in their approach to
  the review?
• Will the results of the paper help me in my
  philosophical or evidence based approach to
  patient care?

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