Types of reviews

• Reviews in general

  In the literature there is no consensus on how to describe and define different types of reviews. The different types of reviews are characterised by both similarities and differences (Gough, Thomas & Oliver, 2012).

  Moreover, the rather unprecise definitions mean that most reviews can be placed under more headings in the overview above (Grant & Booth, 2009).

  Please note, that it is not possible to make a totally precise definition of different types of reviews.

  Within the field of health, the different types of reviews may be more precisely defined. See the article by Grant & Booth below where the different types of reviews are included.

  Overall, the search and selection process in connection with reviews consist of the following phases: defining of the research question, defining of the different aspects of the research question, finding good search words for each aspect, selecting databases, making systematic searches in different databases and selecting texts on the basis of inclusion and exclusion criteria.  

  During the whole process it should be noted: which searches in which databases and how many hits? How many went through the first screening on e.g. title, how many went through the second screening on e.g. abstract and how many could be used in the review after reading in full?

  A way to make the search and selection of the material transparent is to make a flow diagram e.g. on PRISMA where you can see a suggested flow diagram.

  When this work is done, you proceed with synthesising and analysing data.
   

  Bibliography

  Grant, M. J., & Booth, A. (2009). A typology of reviews: An analysis of 14 review types and associated methodologies. Health Information and Libraries Journal, 26(2), 91–108. https://doi.org/10.1111/j.1471-1842.2009.00848.x

  Gough, D., Thomas, J., & Oliver, S. (2012). Clarifying differences between review designs and methods. Systematic Reviews, 1(28), 1–9. https://doi.org/10.1186/2046-4053-1-28

• Literature review

  A literature review can be defined as a synthesis and analysis of scientific material on a specific subject (Garrard, 2014).

  This method tries to identify what has previously been written about a certain subject, which makes it possible to sum up and add to previous work, to avoid double work and to identify gaps in the research field. 

  This covers a very varying degree of comprehensiveness and there is thus a risk of bias and that certain important aspects of the literature have been missed (Grant & Booth, 2009).

  The method does not necessarily use standards for search protocols and reporting of searches. The term ”literature review” is by some used synonymously with the term Narrative reviews (Grant & Booth, 2009)

  	Literature review
  Timeframe	Variable.
  Sources	Selected sources and databases for searching.
  Searches	Searches can be more or less comprehensive (Grant & Booth, 2009).
  Synthesis	Often narrative (Grant & Booth, 2009)

  
  Bibliography

  Garrard, J. (2014). Health sciences literature review made easy: the matrix method e (4. udg.). Burlington: Jones & Bartlett Learning.

  Grant, M. J., & Booth, A. (2009). A typology of reviews: An analysis of 14 review types and associated methodologies. Health Information and Libraries Journal, 26(2), 91–108. https://doi.org/10.1111/j.1471-1842.2009.00848.x

• Narrative review

  Narrative reviews rarely describe the search methods applied to find and select the literature (Callcut & Branson). Thus, a systematic information searching has not necessarily been used and the narrative review can tend to focus on a limited number of studies which are based on what was accessible and/or what the researcher has chosen (Uman, 2011).

  The term Narrative review is by some used synonymously with the term Literature review (Grant & Booth, 2009).

  	Narrative review
  Timeframe	Variable.
  Sources	A limited number of sources and not always sources mentioned (Callcut & Branson, 2009).
  Searches	It is not always described how searches were made (Callcut & Branson, 2009; Uman, 2011).
  Synthesis	Narrative synthesis.

  
  Bibliography

  Callcut, R. a, & Branson, R. D. (2009). How to read a review paper. Respiratory care, 54(10), 1379–85.

  Grant, M. J., & Booth, A. (2009). A typology of reviews: An analysis of 14 review types and associated methodologies. Health Information and Libraries Journal, 26(2), 91–108. https://doi.org/10.1111/j.1471-1842.2009.00848.x

  Uman, L. S. (2011). Information management for the busy practitioner: Systematic reviews and meta-analyses. Journal of the American Academy of Child and Adolescent Psychiatry, 20(1), 57–59. https://doi.org/10.1016/j.revmed.2014.05.011

• Rapid review

  Assessment of the current knowledge of a given policy or practice subject. Uses systematic review methods to search for and assess the quality of existing research. Is often applied in connection with short deadlines. The extent of the systematic methods depends on the limitation of the field and the search strategy (Virginia Commonwealth University, u.å.). 
  
  

  	Rapid review
  Timeframe	Variable – the narrower the limitation of the field and search strategy, the shorter the time.
  Sources	Existing research, limited review of the amount of grey literature (Grant, 2009).
  Searches	The comprehensiveness of the literature search and thus the quality assessment of findings depend on possible timeframe for the project (Grant, 2009).
  Synthesis	Typical narrative and in tabular form (Grant, 2009).

  
  Bibliography

  Grant, M. J., & Booth, A. (2009). A typology of reviews: An analysis of 14 review types and associated methodologies. Health Information and Libraries Journal, 26(2), 91–108. https://doi.org/10.1111/j.1471-1842.2009.00848.x

  Virginia Commonwealth University. (u. å.). Rapid Review Protocol. Hentet fra https://guides.library.vcu.edu/rapidreview

• Rapid Evidence Assessments (REA)

  A systematic mapping of research within a smaller and limited field. Consists of explicit and transparent selection and quality criteria for the studies to be included in the review as well as the level of information to be met for each study (Varker et al., 2015).

  REA is considered an alternative to the more time-demanding systematic reviews and is gaining ground as decision-makers and practitioners demand quicker answers (Thomas, Newman & Oliver, 2013).

  Is equated with Rapid reviews (Varker et al., 2015).

  	Rapid Evidence Assessments (REA)
  Timeframe	Depends on the timeframe of the project, but typically between 1 and 6 months (Thomas et. Al, 2013).
  Sources	Limited number of databases and excludes non-published research. Includes typically only specific research designs.
  Searches	Characterised by searching in selected databases.
  Synthesis	Narrative.

  
  Bibliography

  Thomas, J., Newman, M., & Oliver, S. (2013). Rapid evidence assessments of research to inform social policy: Taking stock and moving forward. Evidence and Policy, 9(1), 5–27. https://doi.org/10.1332/174426413X662572
  
  Varker, T., Forbes, D., Dell, L., Weston, A., Merlin, T., Hodson, S., & O’Donnell, M. (2015). Rapid evidence assessment: Increasing the transparency of an emerging methodology. Journal of Evaluation in Clinical Practice, 21(6), 1199–1204. https://doi.org/10.1111/jep.12405

• Scoping review

  A scoping review maps existing literature within a specific field and identifies gaps in the existing research/literature (Peters et al., 2015). At the same time, it attempts to give an indication of the extent and type of accessible literature within a field (Paré, Trudel, Jaana, & Kitsiou, 2015)

  A Scoping review is also called Scoping Study, Systematic Scoping Review, Scoping Report, Scope of the Evidence, Rapid Scoping Review, Structured Literature Review, Scoping Project and Scoping Meta Review (Temple University Libraries, 2018).

  	Scoping review
  Timeframe	Variable.
  Sources	Initial assessment of the potential amount of scientific literature  (Grant & Booth, 2009).
  Searches	Comprehensiveness of the search is determined by limitations in time and extent of the review. May include ongoing research (Grant & Booth, 2009). A systematic search is made (Pedersen, 2017).
  Synthesis	Tabular form with narrative comments and maybe a visual presentation of the evidence (Grant & Booth, 2009).

  
  Bibliography

  Grant, M. J., & Booth, A. (2009). A typology of reviews: An analysis of 14 review types and associated methodologies. Health Information and Libraries Journal, 26(2), 91–108. https://doi.org/10.1111/j.1471-1842.2009.00848.x

  Paré, G., Trudel, M. C., Jaana, M., & Kitsiou, S. (2015). Synthesizing information systems knowledge: A typology of literature reviews. Information and Management. https://doi.org/10.1016/j.im.2014.08.008

  Pedersen, P. U. (2017). Fra forskning til praksis. Kbh.: Munksgaard.
  
  Peters, M. D. J., Godfrey, C. M., Khalil, H., McInerney, P., Parker, D., Soares, C. B., & Peters  Christina M ; Khalil, Hanan ; Mcinerney, Patricia ; Parker, Deborah ; Soares, Cassia Baldini, M. D. J. ; G. (2015). Guidance for conducting systematic scoping reviews. International Journal of Evidence-Based Healthcare, 13(3), 141–146.

  Temple University Libraries. (2018). Systematic Reviews and Other Review Types. Hentet fra http://guides.temple.edu/c.php?g=78618&p=4156607

• State-of-the-art review

  In several places equated with research overviews or research mapping of a specific limited field. A State-of-the-art review aims at providing an overview of research-based knowledge within typically a broader field. May indicate areas where more research is needed (Grant & Booth, 2009).
  
  

  	State-of-the-art review
  Timeframe	Variable.
  Sources	No formal framework concerning quality.
  Searches	Aims at a thorough search of existing research-based knowledge (Grant & Booth, 2009).
  Synthesis	Typically narrative.

  
  Bibliography

  Grant, M. J., & Booth, A. (2009). A typology of reviews: An analysis of 14 review types and associated methodologies. Health Information and Libraries Journal, 26(2), 91–108. https://doi.org/10.1111/j.1471-1842.2009.00848.x

• Systematic review

  The purpose of a systematic review is to identify all relevant research within a specific subject and then assess the quality of the research. Both literature search and quality assessment of the identified literature are performed systematically and are also documented. A systematic review must be completely transparent and verifiable. Is used for study questions relating to the effect of a given intervention (Thomas m.fl., 2013).

  	Systematic review
  Timeframe	Time-demanding – between 9 and 12 months.
  Sources	All relevant.
  Searches	Aims at a thorough and comprehensive search (Syddansk Universitetsbibliotek, u.å.).
  Synthesis	Typically narrative and maybe supplemented by tables (Syddansk Universitetsbibliotek, 2021).

  
  Bibliography
  Syddansk Universitetsbibliotek. (u.å.). Type af review karakteriseret efter anvendt metode. SDU. https://www.sdu.dk/-/media/files/bibliotek/bibpdf/type+af+review+karakteriseret+efter+anvendt+metode.pdf

  Syddansk Universitetsbibliotek. (2021). Systematiske reviews. SDU. https://www.sdu.dk/da/bibliotek/forskere/litteratursoegninger+og+reviews/systematiske+reviews

  Thomas, J., Newman, M., & Oliver, S. (2013). Rapid evidence assessments of research to inform social policy: Taking stock and moving forward. Evidence and Policy, 9(1), 5–27. https://doi.org/10.1332/174426413X662572

• Meta-analysis

  A meta-analysis is a statistical method to combine and synthesise quantitative data from different primary studies with the purpose of creating a new foundation of parts of the results from primary studies (Johansen & Pors, 2013). To obtain valid meta-analyses, all included studies must be adequately similar. This concerns characteristics such as study population, the intervention explored and not least that what is measured is measured in the same way and with the same time interval (Grant & Booth, 2009).

  	Meta-analysis
  Timeframe	Relatively time-demanding – depending on the number of studies on the subject in question.
  Sources	All relevant.
  Searches	Aims at a thorough and comprehensive search which is systematic and documented.
  Synthesis	Graphic or in tabular form with narrative comments (Syddansk Universitetsbibliotek, u.å.).

  
  Bibliography

  Grant, M. J., & Booth, A. (2009). A typology of reviews: An analysis of 14 review types and associated methodologies. Health Information and Libraries Journal, 26(2), 91–108. https://doi.org/10.1111/j.1471-1842.2009.00848.x

  Johansen, C. G., & Pors, N. O. (2013). Evidens og systematiske reviews : en introduktion. Frederiksberg: Samfundslitteratur.

  Syddansk Universitetsbibliotek. (u.å.). Type af review karakteriseret efter anvendt metode. SDU. https://www.sdu.dk/-/media/files/bibliotek/bibpdf/type+af+review+karakteriseret+efter+anvendt+metode.pdf

• Meta-synthesis

  A meta-synthesis collects and synthesises qualitative research within a specific field. The meta-synthesis interprets other researchers’ interpretations in a total, new interpretation to accumulate the knowledge, similar to a meta-analysis; however, in a meta-synthesis the accumulation is not made by making comparisons and statistical calculations but by collecting and interpreting the findings of others (Frederiksen, Beedholm, & Glasdam, 2015).
  
  The meta-synthesis as a method is developed with the purpose of obtaining a full picture of qualitative research findings in a systematic way (Bidstrup Jørgensen & Steenfeldt, 2010, s. 31).

  	Meta-synthesis
  Timeframe	Relatively time-demanding – depending on the number of studies on the subject in question.
  Sources	All relevant.
  Searches	Aims at a thorough and comprehensive search which is systematic and documented.
  Synthesis	Narrative.

  
  Bibliography

  Bidstrup Jørgensen, B., & Steenfeldt, V. Ø. (Red.). (2010). Med sygeplejeteori som referenceramme - i forskning og udvikling. Kbh.: Gad.

  Frederiksen, K., Beedholm, K., & Glasdam, S. (2015). Litteraturreview. I S. Glasdam (Red.), Bachelorprojekter indenfor det sundhedsfaglige område : indblik i videnskabelige metoder (2. udg., s. 53–62). Kbh.: Nyt Nordisk Forlag.