what is a traditional literature review

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Traditional reviews vs. systematic reviews

Posted on 3rd February 2016 by Weyinmi Demeyin

Millions of articles are published yearly (1) , making it difficult for clinicians to keep abreast of the literature. Reviews of literature are necessary in order to provide clinicians with accurate, up to date information to ensure appropriate management of their patients. Reviews usually involve summaries and synthesis of primary research findings on a particular topic of interest and can be grouped into 2 main categories; the ‘traditional’ review and the ‘systematic’ review with major differences between them.

Traditional reviews provide a broad overview of a research topic with no clear methodological approach (2) . Information is collected and interpreted unsystematically with subjective summaries of findings. Authors aim to describe and discuss the literature from a contextual or theoretical point of view. Although the reviews may be conducted by topic experts, due to preconceived ideas or conclusions, they could be subject to bias.

Systematic reviews are overviews of the literature undertaken by identifying, critically appraising and synthesising results of primary research studies using an explicit, methodological approach(3). They aim to summarise the best available evidence on a particular research topic.

The main differences between traditional reviews and systematic reviews are summarised below in terms of the following characteristics: Authors, Study protocol, Research question, Search strategy, Sources of literature, Selection criteria, Critical appraisal, Synthesis, Conclusions, Reproducibility, and Update.

Traditional reviews

• Authors: One or more authors usually experts in the topic of interest
• Study protocol: No study protocol
• Research question: Broad to specific question, hypothesis not stated
• Search strategy: No detailed search strategy, search is probably conducted using keywords
• Sources of literature: Not usually stated and non-exhaustive, usually well-known articles. Prone to publication bias
• Selection criteria: No specific selection criteria, usually subjective. Prone to selection bias
• Critical appraisal: Variable evaluation of study quality or method
• Synthesis: Often qualitative synthesis of evidence
• Conclusions: Sometimes evidence based but can be influenced by author’s personal belief
• Reproducibility: Findings cannot be reproduced independently as conclusions may be subjective
• Update: Cannot be continuously updated

Systematic reviews

• Authors: Two or more authors are involved in good quality systematic reviews, may comprise experts in the different stages of the review
• Study protocol: Written study protocol which includes details of the methods to be used
• Research question: Specific question which may have all or some of PICO components (Population, Intervention, Comparator, and Outcome). Hypothesis is stated
• Search strategy: Detailed and comprehensive search strategy is developed
• Sources of literature: List of databases, websites and other sources of included studies are listed. Both published and unpublished literature are considered
• Selection criteria: Specific inclusion and exclusion criteria
• Critical appraisal: Rigorous appraisal of study quality
• Synthesis: Narrative, quantitative or qualitative synthesis
• Conclusions: Conclusions drawn are evidence based
• Reproducibility: Accurate documentation of method means results can be reproduced
• Update: Systematic reviews can be periodically updated to include new evidence

Decisions and health policies about patient care should be evidence based in order to provide the best treatment for patients. Systematic reviews provide a means of systematically identifying and synthesising the evidence, making it easier for policy makers and practitioners to assess such relevant information and hopefully improve patient outcomes.

• Fletcher RH, Fletcher SW. Evidence-Based Approach to the Medical Literature. Journal of General Internal Medicine. 1997; 12(Suppl 2):S5-S14. doi:10.1046/j.1525-1497.12.s2.1.x. Available from:  http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1497222/
• Rother ET. Systematic literature review X narrative review. Acta paul. enferm. [Internet]. 2007 June [cited 2015 Dec 25]; 20(2): v-vi. Available from: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-21002007000200001&lng=en. http://dx.doi.org/10.1590/S0103-21002007000200001
• Khan KS, Ter Riet G, Glanville J, Sowden AJ, Kleijnen J. Undertaking systematic reviews of research on effectiveness: CRD’s guidance for carrying out or commissioning reviews. NHS Centre for Reviews and Dissemination; 2001.

Weyinmi Demeyin

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No Comments on Traditional reviews vs. systematic reviews

THE INFORMATION IS VERY MUCH VALUABLE, A LOT IS INDEED EXPECTED IN ORDER TO MASTER SYSTEMATIC REVIEW

Thank you very much for the information here. My question is : Is it possible for me to do a systematic review which is not directed toward patients but just a specific population? To be specific can I do a systematic review on the mental health needs of students?

Hi Rosemary, I wonder whether it would be useful for you to look at Module 1 of the Cochrane Interactive Learning modules. This is a free module, open to everyone (you will just need to register for a Cochrane account if you don’t already have one). This guides you through conducting a systematic review, with a section specifically around defining your research question, which I feel will help you in understanding your question further. Head to this link for more details: https://training.cochrane.org/interactivelearning

I wonder if you have had a search on the Cochrane Library as yet, to see what Cochrane systematic reviews already exist? There is one review, titled “Psychological interventions to foster resilience in healthcare students” which may be of interest: https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD013684/full You can run searches on the library by the population and intervention you are interested in.

I hope these help you start in your investigations. Best wishes. Emma.

La revisión sistemática vale si hay solo un autor?

HI Alex, so sorry for the delay in replying to you. Yes, that is a very good point. I have copied a paragraph from the Cochrane Handbook, here, which does say that for a Cochrane Review, you should have more than one author.

“Cochrane Reviews should be undertaken by more than one person. In putting together a team, authors should consider the need for clinical and methodological expertise for the review, as well as the perspectives of stakeholders. Cochrane author teams are encouraged to seek and incorporate the views of users, including consumers, clinicians and those from varying regions and settings to develop protocols and reviews. Author teams for reviews relevant to particular settings (e.g. neglected tropical diseases) should involve contributors experienced in those settings”.

Thank you for the discussion point, much appreciated.

Hello, I’d like to ask you a question: what’s the difference between systematic review and systematized review? In addition, if the screening process of the review was made by only one author, is still a systematic or is a systematized review? Thanks

Hi. This article from Grant & Booth is a really good one to look at explaining different types of reviews: https://onlinelibrary.wiley.com/doi/10.1111/j.1471-1842.2009.00848.x It includes Systematic Reviews and Systematized Reviews. In answer to your second question, have a look at this Chapter from the Cochrane handbook. It covers the question about ‘Who should do a systematic review’. https://training.cochrane.org/handbook/current/chapter-01

A really relevant part of this chapter is this: “Systematic reviews should be undertaken by a team. Indeed, Cochrane will not publish a review that is proposed to be undertaken by a single person. Working as a team not only spreads the effort, but ensures that tasks such as the selection of studies for eligibility, data extraction and rating the certainty of the evidence will be performed by at least two people independently, minimizing the likelihood of errors.”

I hope this helps with the question. Best wishes. Emma.

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Literature Review - what is a Literature Review, why it is important and how it is done

What are literature reviews, goals of literature reviews, types of literature reviews, about this guide/licence.

• Strategies to Find Sources
• Evaluating Literature Reviews and Sources
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 What is a literature review? "A literature review is an account of what has been published on a topic by accredited scholars and researchers. In writing the literature review, your purpose is to convey to your reader what knowledge and ideas have been established on a topic, and what their strengths and weaknesses are. As a piece of writing, the literature review must be defined by a guiding concept (e.g., your research objective, the problem or issue you are discussing, or your argumentative thesis). It is not just a descriptive list of the material available, or a set of summaries. " - Quote from Taylor, D. (n.d) "The literature review: A few tips on conducting it"

Source NC State University Libraries. This video is published under a Creative Commons 3.0 BY-NC-SA US license.

What are the goals of creating a Literature Review?

• To develop a theory or evaluate an existing theory
• To summarize the historical or existing state of a research topic
• Identify a problem in a field of research 

- Baumeister, R.F. & Leary, M.R. (1997). "Writing narrative literature reviews," Review of General Psychology , 1(3), 311-320.

When do you need to write a Literature Review?

• When writing a prospectus or a thesis/dissertation
• When writing a research paper
• When writing a grant proposal

In all these cases you need to dedicate a chapter in these works to showcase what have been written about your research topic and to point out how your own research will shed a new light into these body of scholarship.

Literature reviews are also written as standalone articles as a way to survey a particular research topic in-depth. This type of literature reviews look at a topic from a historical perspective to see how the understanding of the topic have change through time.

What kinds of literature reviews are written?

• Narrative Review: The purpose of this type of review is to describe the current state of the research on a specific topic/research and to offer a critical analysis of the literature reviewed. Studies are grouped by research/theoretical categories, and themes and trends, strengths and weakness, and gaps are identified. The review ends with a conclusion section which summarizes the findings regarding the state of the research of the specific study, the gaps identify and if applicable, explains how the author's research will address gaps identify in the review and expand the knowledge on the topic reviewed.
• Book review essays/ Historiographical review essays : This is a type of review that focus on a small set of research books on a particular topic " to locate these books within current scholarship, critical methodologies, and approaches" in the field. - LARR
• Systematic review : "The authors of a systematic review use a specific procedure to search the research literature, select the studies to include in their review, and critically evaluate the studies they find." (p. 139). Nelson, L.K. (2013). Research in Communication Sciences and Disorders . San Diego, CA: Plural Publishing.
• Meta-analysis : "Meta-analysis is a method of reviewing research findings in a quantitative fashion by transforming the data from individual studies into what is called an effect size and then pooling and analyzing this information. The basic goal in meta-analysis is to explain why different outcomes have occurred in different studies." (p. 197). Roberts, M.C. & Ilardi, S.S. (2003). Handbook of Research Methods in Clinical Psychology . Malden, MA: Blackwell Pub.
• Meta-synthesis : "Qualitative meta-synthesis is a type of qualitative study that uses as data the findings from other qualitative studies linked by the same or related topic." (p.312). Zimmer, L. (2006). "Qualitative meta-synthesis: A question of dialoguing with texts," Journal of Advanced Nursing , 53(3), 311-318.

Guide adapted from "Literature Review" , a guide developed by Marisol Ramos used under CC BY 4.0 /modified from original.

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