The Literature Review: Systematic Reviews

What are Systematic Reviews?

 

A systematic review attempts to identify, appraise and synthesize all the empirical evidence that meets pre-specified eligibility criteria to answer a given research question. Researchers conducting systematic reviews use explicit methods aimed at minimizing bias, in order to produce more reliable findings that can be used to inform decision making.

About Cochrane Reviews, Cochrane Library

All good literature reviews should be carried out in an organised, systematic way.

Systematic reviews take this further, being done and reported in a way that makes them:

  • rigorous
  • transparent
  • reproducible
  • minimises bias

Formal systematic or scoping reviews intended for publication or to inform practice should follow standards described in PRISMA, the Cochrane Handbook for Systematic Reviews of Interventions or the JBI Manual for Evidence Synthesis.

See the VU Systematic Literature Reviews guide for more information.

Systematic or scoping reviews being done as part of coursework may be less rigorous but may find it useful to refer to these standards.

At a minimum these reviews should include:

  • sources - databases and other places that were searched
  • methods - search terms and strategy. The search strategy should be reproduced in full.
  • inclusion & exclusion criteria

Cochrane - what are systematic reviews? Video

Narrative vs. systematic

Differences between Narrative and Systematic Reviews?

 

 
  Narrative Literature Reviews Systematic Literature Reviews
Focus:

Describe and critically analyse the literature on a specific topic from a theoretical and contextual point of view.

Clear focus on appraising the quality of evidence encountered in the literature, often with a view to informing and improving practice outcomes
Explicitness of search strategy: Often relatively undefined Clearly defined and systematically applied
Comprehensiveness: May offer wide coverage, but does not necessarily aspire to be comprehensive Aims to be as exhaustive as possible
Decisions about inclusion/exclusion of material: Can be selective and piecemeal Clear protocol is devised to guide decision making about what is included and excluded
Potential for bias: Author(s)’ decision-making process is often not explicit so there is scope for bias Collaborative creation of protocol and transparent process tend to minimise potential for bias
Validity and reliability: The lack of transparency about how the review has been carried out and the potential for ad hoc inclusion of material raises questions about the confidence that can be placed in the findings Due to the systematic use of the protocol in all stages of the research, and the transparency with which review decisions are described, findings are likely to be valid and reliable
Key advantages:

Easy to understand.

Provide a manageable overview of the state of knowledge on a topic.

Narrative reviews can be useful for synthesising ideas, theories and concepts from a broad range of literature

The systematic nature means that it is of a high quality and is repeatable

Can have confidence in conclusions.

Key disadvantages:

Quality can be variable.

Lack of transparency can make it difficult to assess the rigour, bias or completeness of the review.

Although systematic reviews can be good at identifying ‘what’ works, they may not always be the most appropriate tool for identifying ‘why’ something works

Focussed nature means lack of contextual explanation.

adapted from 'What is a literature review?', in R Kiteley & C Stogdon, Literature reviews in social work, SAGE Publications Ltd., 2014. 

Before you begin your systematic review

Before you begin your systematic review, it can be helpful to read other reviews related to your topic (and also make sure you are not 're-inventing the wheel'). PROSPERO is an international register of systematic reviews in health and social care, welfare, public health, education, crime, justice, and international development, where there is a health related outcome. 

You can also search a range of subject databases (available at VU Library), such as such as MEDLINE, CINAHL, PsycINFO and limit the search to "systematic review". Also Cochrane Library, which is a database that focuses specifically on indexing evidence-based medicine, systematic reviews, etc. For instructions on how to access Library databases, consult the Searching the Literature section of this guide.

Formulate the research question

The following are frameworks that you can use to help formulate a clear and focused research question, which you can then use to convert into an effective search strategy for your review:

PICO for quantitative studies
P Patient, Population or Problem
I Intervention or Exposure
C Comparison
O Outcome
  ​Lawani, M. A., Valéra, B., Fortier-Brochu, E., Légaré, F., Carmichael, P. H., Côté, L., ... Giguere, A. M. C. (2017). Five shared decision-making tools in 5 months: use of rapid reviews to develop decision boxes for seniors living with dementia and their caregivers. Systematic Reviews, 6(56), 1-12. doi:10.1186/s13643-017-0446-2.

 

 

PICo for qualitative studies
P Population
I Interest
Co Context
 

Rathbone, J., Albarqouni, L., Bakhit, M., Beller, E., Byambasuren, O., Hoffmann, T., … Glasziou, P. (2017). Expediting citation screening using PICo-based title-only screening for identifying studies in scoping searches and rapid reviews. Systematic Reviews, 6(1), 1-7. doi:10.1186/s13643-017-0629-x.

SPIDER for qualitative and mixed methods research studies
S Sample
PI Phenomenon of Interest
D Design
E Evaluation
R Research type
  Cooke, A., Smith, D., & Booth, A. (2012). Beyond PICO: The SPIDER Tool for Qualitative Evidence Synthesis. Qualitative Health Research, 22(10), 1435–1443. doi:10.1177/1049732312452938.

 

SPICE for qualitative evidence
S Setting
P Perspective
I Intervention
C Comparison
E Evaluation
  Harris, J. L. , Booth, A., Cargo, M., Hannes, K., Harden, A., Flemming, K., ... Noyes, J. (2018). Cochrane Qualitative and Implementation Methods Group guidance series—paper 2: methods for question formulation, searching, and protocol development for qualitative evidence synthesis, Journal of Clinical Epidemiology, 97(4), 39-48. doi:10.1016/j.jclinepi.2017.10.023.

 

The PRISMA Statement

The PRISMA Statement is a great starting point for any systematic literature review as it lays out the steps/tasks involved in an uncomplicated way. The PRISMA Statement consists of a checklist and flow diagram.

If you have used PRISMA in your systematic review, you must cite it. The PRISMA statement has been published in several journal articles, and PRISMA recommend that you cite via one of these, rather than the website directly. For more information on how to cite PRISMA, see here.

Systematic review tools

EndNote - a reference management tool which helps you to save and manage bibliographic references. 

Covidence - an online systematic review program. You can access the free trial version to work out if it's suitable for your project. Otherwise it is free to use for Cochrane authors.

RevMan 5 - the software used for preparing and maintaining Cochrane Reviews.

Guides to writing a systematic literature review