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Systematic Reviews: Home

What is a Systematic Review?

A systematic review attempts to collate all empirical evidence that fits pre-specified eligibility criteria in order to answer a specific research question.

It uses explicit, systematic methods that are selected with a view to minimizing bias, thus providing more reliable findings from which conclusions can be drawn and decisions made.

The key characteristics of a systematic review are:

  • a clearly stated set of objectives with pre-defined eligibility criteria for studies
  • an explicit, reproducible methodology
  • a systematic search that attempts to identify all studies that meet the eligibility criteria
  • an assessment of the validity of findings of the included studies
  • a systematic presentation and synthesis of the characteristics and findings of the included studies

A Systematic Review can be either quantitative or qualitative. 

 

A quantitative systematic review will include studies that have numerical data.
A qualitative systematic review derives data from observation, interviews, or verbal interactions and focuses on the meanings and interpretations of the participants.  It will include focus groups, interviews, observations and diaries.                                         

Cochrane Handbook for Systematic Reviews of Interventions - volume 6, 2019
https://training.cochrane.org/handbook/current
Note.  The Methodological Expectations of Cochrane Intervention Reviews (MECIR Standards) are now incorporated into the Cochrane Handbook

 

Other types of reviews

  • Rapid reviews are a form of accelerated systematic review. They are usually undertaken when decision makers have urgent and emerging needs which require evidence produced on a short time frame. Typically, to compensate for the short time frame of a rapid review, methodological rigour may be sacrificed. Cochrane defines rapid reviews as "a form of knowledge synthesis that accelerates the process of conducting a traditional systematic review through streamlining or omitting specific methods to produce evidence for stakeholders in a resource-efficient manner.”

    Further reading and guidance: 

    Klerings, I., Robalino, S., Booth, A., Escobar-Liquitay, C. M., Sommer, I., Gartlehner, G., Devane, D., & Waffenschmidt, S. (2023) Rapid Review methods series: Guidane on literature search. BJM Evidence-Based Medicine, 28(6), 412-417
    Hamel C, Michaud A, Thuku M, Skidmore B, Stevens A, et al. Defining rapid reviews: a systematic scoping review and thematic analysis of definitions and defining characteristics of rapid reviews. J Clin Epi. 2021;129:74-85. doi: 10.1016/j.jclinepi.2020.09.041 

  • Umbrella reviews are sometimes referred to as a "review of reviews". They are an attempt to identify and appraise, extract and summarises all the evidence from research syntheses related to a topic or question. 

     Umbrella reviews may: Include analyses of different interventions for the same problem or condition.

  • Analyse the same intervention and condition, but different outcomes.
  • Analyse the same intervention but different conditions, problems or populations.

  • Umbrella reviews offer the possibility to address a broad scope of issues related to the topic of interest.

    Adapted from: Aromataris E, Fernandez R, Godfrey C, Holly C, Khalil H, Tungpunkom P. Chapter 10: Umbrella Reviews. In: Aromataris E, Munn Z (Editors). JBI Manual for Evidence Synthesis. JBI, 2020. Available from https://synthesismanual.jbi.global.  https://doi.org/10.46658/JBIMES-20-11 

Please check the flow charts below to guide you to a review type that best suits your research project.

Cornell University Review Methodology Decision Tree

St Michael's Unity Health Toronto, Knowledge Synthesis Decision Tool

How Can the Library Help?

Librarians support the systematic review process by using their searching expertise to:

  • identify existing systematic reviews on a topic
  • recommend relevant databases to search
  • develop and review search strategies in databases such as Medline, Emcare, Embase & PsycINFO
  • assist with documenting and saving search strategies
  • create EndNote libraries to manage citations
  • obtain articles
  • provide training on database searching and EndNote

The CAHS medical librarian is not able to execute the search on your behalf or collate results.

What is the Systematic Review Process?

  1. Formulate a search question - use PICO for a quantitative review  or PICo for qualitative review
  2. Check for existing reviews or protocols
  3. Write protocol.
  4. Search strategy including databases and keywords.(Search key databases)
  5. Apply Inclusion and Exclusion criteria - decide 
  6. Search for relevant studies. Supplementary and grey literature searching.
  7. Download search results to reference management software (viz. Endnote) and deduplicate.
  8. Obtain full text of included studies.
  9. Screen abstracts/full text against protocol.
  10. Document the search process, including databases searched, number of citations retrieved, and date searched.
  11. Extract and analyse data.
  12. Critically Appraise individual studies.
  13. Synthesis of studies - interpret/analyse results.
  14. Report on findings, documenting all steps in the systematic review process.
  15. Write up results
  16. Publish

Before embarking on a systematic review process

The production of SRs has been prolific. There are concerns are over their quality and usefulness and cost involved executing it.  It is important to consider the following:

  • Have you checked if an SR already exists on your topic? Check for protocols and published reviews.
  • Do you have adequate time and resources, to commit around 12 months to the review?
  • SRs should not be undertaken by just one person. Cochrane recommends multidisciplinary teams work best.
  • To ensure rigour, follow established standards and guidelines.
  • Is an SR the right review type for your topic and/or research question? You may find this decision tree helpful.
  • Familiarise yourself with various review types.
  • Broaden your knowledge about systematic reviews further, by reading as much as you can about the process and find examples of good reviews.

Conducting Systematic Reviews Video

Difference between a systematic review and scoping review

Systematic Review Scoping Review
Focused research question with narrow parameters Research question(s) often broad
Inclusion/exclusion usually defined at outset Inclusion/exclusion can be developed post hoc
Quality filters often applied Quality not an initial priority
Detailed data extraction May or may not involve data extraction
Quantitative synthesis often performed Synthesis more qualitative and typically not quantitative

Formally assesses the quality of studies and generates a
conclusion relating to the focused research question

 

 Used to identify parameters and gaps in a body of literature

Adapted from: Armstrong, R., Hall, B.J., Doyle, J., & Waters, E. (2011). 'Scoping the scope' of a Cochrane review. Journal of Public Health, 33(1), 147-50.http://dx.doi.org/10.1093/pubmed/fdr015.

(from Curtin University Library's Systematic Review guide)