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Types of Medical Literature Reviews

Not all review types listed below are considered as systematic presentations of medical evidence.    Some  reviews are more systematic than others. For publication, systematic reviews and, increasingly, scoping reviews require a research team and creation of a protocol, e.g. Cochrane or Prisma. The table below outlines the characteristics of different types of review literature.   

Review Type Description Search Appraisal Synthesis Analysis
Critical review

Aims to show that writer has extensively searched the literature & critically evaluated its quality. Provides a degree of analysis & conceptual innovation. Often results in hypothesis or model.

Example

 Seeks to identify the most significant items in the field No formal quality assessment. Attempts to evaluate according to contribution Typically narrative, may be conceptual or chronological Significant component: seeks to identify conceptual contribution to embody existing or derive new theory

Literature or Narrative  review

 		 Generic term: published materials that provide examination of recent or current literature. Can cover wide range of subjects at various levels of completeness and comprehensiveness.May include research findings. May or may not include comprehensive searching May or may not include quality assessment Typically narrative  May be chronological, conceptual, thematic, etc.
Mapping review

Map out and categorize existing literature from which to commission further reviews and/or primary research by identifying gaps in research literature.

Example

 

 Completeness of search depends on time/scope constraints No formal quality assessment May be graphical and tabular Characterizes quantity of literature, perhaps by study design and other key features. May identify need for primary or secondary research
Meta-analysis

A study that systematically combines the results of quantitative studies & uses statistical analysis to provide a more precise effect of the results.

Example

 Aims for exhaustive comprehensive searching. May use funnel plot to assess completeness Quality assessment may determine inclusion/exclusion and/or sensitivity analyses Graphical and tabular with narrative commentary Numerical analysis of measures of effect assuming absence of heterogeneity
Mixed methods review

Combination of methods where one significant component is a literature review (usually systematic). In a review context it refers to a combination of review approaches, e.g. combining quantitative with qualitative research.

Example

 Requires either very sensitive search to retrieve all studies or separately conceived quantitative and qualitative strategies Requires either a generic appraisal instrument or separate appraisal processes with corresponding checklists Typically both components will be presented as narrative and in tables. May also employ graphical means of integrating quantitative and qualitative studies Analysis characterizes both literatures and look for correlations  between characteristics or use gap analysis to identify aspects absent in one literature but present in the other.
Qualitative Systematic review

Integrates or compares the findings from qualitative studies. Looks for themes or constructs that lie in or across individual qualitative studies.

Example

 May employ selective or purposive sampling Quality assessment typically used to mediate messages not for inclusion/exclusion Qualitative narrative synthesis Thematic analysis, may include conceptual models
Rapid review

Assesses what is already known about a policy or practical issue, by using systematic review methods to search and critically appraise existing research.

Example

 Completeness of searching determined by time constraints Time-limited formal quality assessment Typically narrative and tabular Quantities of literature and overall quality /direction of effect of literature
Scoping review

Preliminary investigation of potential size and scope of available research. Aims to identify nature and extent of research evidence (usually including ongoing research). Requires following a protocol, e.g. Cochrane or Prisma. 

Example

 Completeness of searching  determined by time/scope constraints. May include research in progress No formal quality assessment Typically tabular with some narrative commentary Characterizes quantity and quality of literature, perhaps by study design and other key features. Attempts to specify a viable review
Systematic review

 Poses a well formulated research question to systematically search for, appraise and synthesize existing research evidence.  Requires following a protocol, e.g. Cochrane or Prisma. 

Example

 Aims for exhaustive, comprehensive  searching Quality assessment may determine inclusion/ exclusion Typically narrative, may have tabular accompaniment What is known: recommendations for practice. What remains unknown; uncertainty around findings, recommendation for future research
Umbrella review

A review compiling evidence from multiple reviews into one accessible and usable document. Focuses on broad condition or problem. Useful for gathering reviews of   competing interventions. Analyses and highlights   these interventions and their results.

Example

 Identification of component reviews,but no search for primary studies Quality assessment of studies within component reviews and/or of reviews themselves Graphical and tabular with narrative commentary What is known; recommendations for practice.What remains unknown; recommendations for future research

Table adapted from: Grant, M. and Booth,A.(2009) A typology of reviews: an analysis of 14 review types and associated methodologies Health Information and Libraries Journal. 26, pp.91-108.

The CRAAP Test

You have found some information  on a website, or a database, on Google or Google Scholar; but how can you assure yourself that the source of this information is good ?

Use the CRAAP Test to help you evaluate the information you find. Different criteria will be more or less important depending on the type of resource and the type of research you are doing.

Evaluation Criteria

 Currency: The timeliness of the information.

  • When was the information published or posted?
  • Has the information been revised or updated?
  • Does your topic require current information, or will older sources work as well?
  • Are the links functional?   

Relevance:The importance of the information for your needs.

  • Does the information relate to your topic or answer your question?
  • Who is the intended audience?
  • Is the information at an appropriate level (i.e. not too elementary or advanced for your needs)?
  • Have you looked at a variety of sources before determining this is the one you will use?
  • Would you be comfortable citing this source in your research paper?  

Authority: The source of the information.

  • Who is the author / publisher / source / sponsor?
  • What are the author's credentials or organizational affiliations?
  • Is the author qualified to write on the topic?
  • Is there contact information, such as a publisher or email address?
  • Does the URL reveal anything about the author or source (examples: .com .edu .gov .org .net)?  

Accuracy: The reliability, truthfulness and correctness of the content.

  • Where does the information come from?
  • Is the information supported by evidence?
  • Has the information been reviewed or refereed?
  • Can you verify any of the information in another source or from personal knowledge?
  • Does the language or tone seem unbiased and free of emotion?
  • Are there spelling, grammar or typographical errors?

Purpose: The reason the information exists.

  • What is the purpose of the information? Is it to inform, teach, sell entertain or persuade?
  • Do the authors / sponsors make their intentions or purpose clear?
  • Is the information fact, opinion or propaganda?
  • Does the point of view appear objective and impartial?
  • Are there political, ideological, cultural, religious, institutional or personal biases?

Permission for use kindly granted by creator: Sara Blakeslee, California State University, Chico Campus.

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Using both Keyword  & Thesaurus terms in a database search will help you in the following ways.

Using PICO to to create a clinical question

The PICO method helps you derive an answerable clinical question to focus your search for resources on your topic of interest..

Once you have thought about your concepts & some related keyword, & formulated an answerable question, you are ready to choose an appropriate database to search.

Thesaurus/ mesh srch

About Thesaurus Terms:  A database thesaurus or controlled vocabulary is an index used to assign subject information to the research articles contained in database. The main thesaurus used in Medicine is called MeSH (Medical Subject Headings). MeSH is an index of medical terms used by specific databases  to classify all medical research.  When searching databases always check to see which controlled vocabulary is used. For detailed understanding of MeSH, follow this MEDLINE/PubMed Medical Subject Heading  tutorial.

Learn more about searching with subject headings on different databases

Database 

Subject Vocabulary

Subject Search Tutorials
Medline Complete & Cinahl MeSH / Cinahl Headings

 

https://youtu.be/eJJPp9yAIoA
Cochrane Library MeSH

https://youtu.be/HLD7w63rqB0
PsycInfo

Thesaurus of

Psychological

Index terms

https://youtu.be/IiW7rBBNdDg
PubMed MeSH https://youtu.be/o6CTfdx85ys
SCOPUS  No thesaurus https://youtu.be/uEHSnUh0Mag

 

Core Medical Databases

DATABASES COVERAGE PUBLICATION TYPES INCLUDED DATE RANGE
CINAHL Extensive collection nursing & allied health research Primary research articles, reviews, professional association articles, editorials, etc.  1937-present
Cochrane Library of Systemic Reviews Full text source of systematic reviews and ongoing clinical trial protocols. Gold standard systematic reviews on efficacy of clinical treatments 1995- present

Medline Complete  (Ebsco)

 

 Provides user friendly & up-to-date access to full-text & abstracts of all biomedical journals indexed in the Medline subset of PubMed.. Primary research articles, qualitative and quantitative reviews,editorials, etc.
 		 1946- present
PsycINFO  Psychology, behavioural science, mental health Journal articles, book chapters, conference proceedings 1806-present
PubMed PubMed® comprises 32 million+ citations for biomedical literature from MEDLINE; Also  Includes ahead of print citations, full text life science journals from PubMed Central & NCBI bookshelf titles.  Full text & abstracts primary research, systematic reviews, clinical trials, etc.  1946- present
Scopus Multi-disciplinary coverage – large subset of biomedical research Biomedical primary and secondary research articles, professional book series, conference proceedings with  forward citation links to related research 1970-present

Table adapted with permission from Schulich Library, McGill University, Canada.

 

primary seconday tertiary research

Primary

Secondary

 

Tertiary

 

Peer-reviewed

bioscience

journals

Narrative/

Literature

Reviews

 Handbooks
Dissertations

Systematic

Reviews

 Dictionaries

Conference

Proceedings

 Meta-analyses Fact Books

Tabulated

Statistics

Practice/

Treatment

guidelines

 Encyclopedias

 

google advanced search terms

 

allintext : search for documents with specific words in the text allinurl : find search terms in url inauthor :  find books written by specific author intitle : find your term in the title & document link :  find sites that link to a desired URL location : find results from a location (Google News only)
related : find web pages that are similar to a URL (helps find organizations you are not familiar with) site:country code : search for results from a specific country source :  find results from a specific source ? or * : internal & end of word wildcards -  :  exclude a search term from your results “ ” :  search by phrase all words together