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Evidence-Based Practice: Literature Reviews / Systematic Reviews

Introduction

Literature reviews - narrative reviews, critically appraised topics, scoping reviews, rapid reviews, and systematic reviews - vary in their degrees of speed, detail, risk of bias and comprehensiveness.In science, literature reviews are studies which:

  • are based on database searches;
  • summarise the results of research; and
  • have the aim of objectively discussing a specific topic or theme.

There are many types of literature review, but two of the main ones are:

  • narrative (or traditional) review
  • systematic review.

 

The image at above right describes common review types in terms of speed, detail, risk of bias and comprehensiveness.

For more details, see CSU's Library Resource Guides for researchers on

[Image attribution: "Schematic of the main differences between the types of literature review" by Brennan, M. L., Arlt, S. P., Belshaw, Z., Buckley, L., Corah, L., Doit, H., Fajt, V. R., Grindlay, D., Moberly, H. K., Morrow, L. D., Stavisky, J., & White, C. (2020). Critically Appraised Topics (CATs) in veterinary medicine: Applying evidence in clinical practice. Frontiers in Veterinary Science, 7, 314. https://doi.org/10.3389/fvets.2020.00314 is licensed under CC BY 3.0.]

What is a Narrative Review?

A narrative review of the literature provides an overview of the research on a given topic, but usually lacks systematic search protocols or clear criteria for selecting and appraising evidence. They are often qualitative in approach and can be prone to bias.

Photo credit: Urval av de Bocker sum var hunnit Nordisk radets litteraturpris under de 50 ar som priset funnits (3) by Johannes Jansson/norden.org. Licensed under CC BY 2.5 dk via Commons.

What is a Systematic Review?

A systematic review is just that: a systematic review of the literature on a certain topic or to answer a clinical question. Reviewers carry out an extensive search of the literature to identify studies that have sound methodology. They use rigorous, systematic, and documented methods to review and assess the studies for quality, and to pool and summarise the results.

Systematic reviews are not necessarily the highest level of evidence, but they have the advantage of drawing together a number of studies and compiling the results.

A systematic review will often include a meta-analysis. This is where data from a number of valid studies are combined mathematically and then reported as if from a single study.

The best-known source of systematic reviews (for healthcare) is the Cochrane Library's Cochrane Database of Systematic Reviews. Here's how the Cochrane Library defines a systematic review:

"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."
[ from https://www.cochranelibrary.com/about/about-cochrane-systematic-reviews.html ]

See also the More Resources on Systematic Reviews box below for the Cochrane Library's full definition of a systematic review.

Finding Systematic Reviews

Synopses of systematic reviews

Some databases are specific for evidence-based practice material and provide synopses (summaries) of systematic reviews. If you do not have time to look at a detailed systematic review, then a synopsis which summarises the findings of a systematic review might suffice. The synopsis often also has a commentary on the methodological quality and clinical applicability of the review:

  • BMJ Clinical Evidence
    This describes itself as a database of systematic overviews of evidence on clinical interventions, based on appraisals of RCTs and systematic reviews of RCTs. The link here is to this resource in PubMed Central, where this resource is available as an eJournal (one volume per year). From 2003-2005 it was known as Clinical Evidence, and from 2006 onwards as BMJ Clinical Evidence. It ceased publication in June 2016, and has been replaced by BMJ Best Practice(CSU doesn't have a subscription).
  • EBM Reviews - ACP Journal Club
    This Ovid database consists of two journals, now merged, ACP Journal Club and Evidence-Based Medicine. Each record in the database is an abstract and commentary on an individual study or review. The abstract and commentary is available in full-text, with a citation for the original item.

Systematic Reviews

Other evidence-based practice databases are excellent sources of systematic reviews:

  • Cochrane Library
    Probably the best known source of Evidence Based Practice material, consisting of a number of databases, including the Cochrane Database of Systematic Reviews (CDSR), which has systematic reviews and protocols (reviews in preparation) conducted by Cochrane Review Groups, available in full-text.
  • JBI COnNECT+
    The main product of the Joanna Briggs Institute, with evidence-based practice resources in nursing and allied health. Also available on the Ovid platform, where it's known as the Johanna Briggs Institute EBP Database.There are a number of Publication Type limiters, including one for Systematic Reviews, and there is a JBI Library of Systematic Reviews - "a fully refereed library that publishes systematic reviews of literature following the JBI methodology".
  • OTseeker
    A free Australian index of evidence-based practice related to occupational therapy, which you can use to locate systematic reviews. In the Advanced Search screen, if you choose to search by Method, the two options are Randomised Controlled Trial, and Systematic Review.
  • PEDro
    A free Australian index of evidence-based practice material relevant to physiotherapy, which you can use to locate systematic reviews. In the Advanced Search screen, the Method field drop-down menu has three options: practice guideline; systematic review; and clinical trial.
  • speechBITE
    A free Australian index of evidence-based practice material related to speech pathology, which you can use to locate systematic reviews. In the Advanced Search screen, the Research Design field drop-down menu has six options including one for Systematic Review.
  • psycBITE
    A free Australian index of evidence-based practice material, including systematic reviews, on psychological problems and issues resulting from acquired brain impairment. In Search, the Method field drop-down menu includes an option for Systematic Reviews.
  • EvidenceAlerts
    This site, provided by BMJ Group and McMaster University's Health Information Research Unit, is free but you need to register. You can get citations for selected articles (and links to full-text if available free) from more than 120 journals, plus email alerts about new evidence. Articles are rated for clinical relevance and "newsworthiness".
  • Nursing+
    This service, also from McMaster University's Health Information Research Unit, has two "models", with the Basic model being free. Registration is required. The Basic model gives access to a searchable database of articles that is continuously updated, with articles being rated for clinical relevance and "newsworthiness".

Health/Medical Databases

You can also search the major health/medical databases for systematic reviews. Some databases have specific limiters for systematic reviews:

  • CINAHL Plus with Full Text
    This major nursing and allied health database, available in the EBSCOhost platform, has a limiter for Publication Type > Systematic Reviews. This limiter is available from the panel of limiters on the Advanced Search screen.
  • MEDLINE
    MEDLINE is available to CSU users in a number of platforms but the main one would be Ovid, where it's available in a number of date packages. MEDLINE has authoritative information on medicine and a range of related disciplines. You can use systematic review as a search term, or apply the limiter to Topic Reviews (Cochrane). Note that the limiter for Evidence Based Medicine Reviews will return topic reviews but also articles used in a topic review, or reviewed in ACP Journal Club or DARE.
  • PubMed
    PubMed is effectively the free version of MEDLINE. After you have run a search, you can limit your results to Systematic Reviews, but to get that as a limiter you might need to click on "Customize", under the heading of Article Types.
  • PsycINFO
    Like MEDLINE, PsycINFO is available in Ovid. It covers scholarly literature in the psychological, social, behavioural, and health sciences. After you have run a search, you can click on Additional Limits and, at the Methodology drop-down menu, choose the limiter for 0830 Systematic Review.

Citation Databases

If your research or topic is cross-disciplinary, you might benefit from searching in one of the large citation indexes:

  • Scopus
    This is a multi-subject citation and abstract database of research literature, known for its citation-tracking and bibliometric features. There is no specific limiter for systematic reviews but you can use "systematic review" as a search term.

More Resources on Systematic Reviews

Videos

Websites

Library Guides