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Systematic Reviews: A How-To Guide

Overview of systematic review steps and resources to assist researchers conducting reviews

A. Search

Search for Literature

When searching for scholarly and/or grey literature, be conscious of the type of literature you are retrieving.

Levels of evidence are a way to designate the strength of studies based on the methodological quality of their design, validity, and applicability to patient care. The lowest level is at the bottom of the pyramid, the highest is on the top. It is important to use the highest level of evidence that you can for a systematic review, recognizing that for some topics, you may need to use lower quality studies.

Systematic Review:  A summary of the medical literature that uses explicit methods to perform a comprehensive literature search & critical appraisal of individual studies & that uses appropriate statistical techniques to combine these valid studies

Critically Appraised Topics (Evidence Synthesis): Summarizes the current state of knowledge about the prevention and treatment of clinical conditions, based on thorough searches and appraisal of the literature.

Critically Appraised Individual Articles (Article Synopses):  A short summary of an article from the literature, created to answer a specific clinical question.

Randomized Controlled Trial:  Participants are randomly allocated into experimental or control groups & are followed over time for the variables/outcomes of interest.  Clinicians & laboratory workers may also be blinded to participant groups.

Cohort Study:  Identifies participants who currently have a certain condition or receive a particular treatment are followed over time & compared with another group of people who are not affected by the condition.

Case Control Study:  Identifies participants who have a certain outcome (cases) & participants without that outcome (controls). Investigators look back over time to see if they had the specific exposure.

Case Report/Case Series:  A report on one or more participants with a particular outcome.  No control group is involved.

(Norwich University, 2020)


Cochrane strongly encourage that review authors include a study flow diagram as recommended by the PRISMA statement.

Guides to Other Levels of Evidence

National Health and Medical Research Council has created a guide to help researchers perform their search. How to Use the Evidence: Assessment and Application of Scientific Evidence

The Joanna Briggs Institute offers a guide to their Levels of Evidence based on the research design of the original experiment.

Centre for Evidence Based Medicine (UK) uses another system for rating evidence used in a systematic review- Levels of Evidence (March 2009)

B. Managing References Using a Citation Management System

Citation Management Software

The thorough nature of systematic reviews means that they involve the use of a lot of references, so a citation management program will keep you organized and save you a lot of time when doing your evidence synthesis. Programs like Endnote, Zotero or Mendeley will store and organize the citations collected during your screening, de-duplicate the results and automatically format in-text citations and bibliographies in your manuscript.

After completing your searches in your selected databases, there will be a number of duplicates. Deduplication is the process of removing these duplicates. Many reference management programs include a deduplication tool. 

Consult UVic's Citation management at UVic: Managing your references research guide to select a tool that suits your needs. 


Systematic Review Management Software

Systematic review management software tools are specifically tailored to the needs of systematic review teams. In addition to reference management, some of these tools can also help with data extraction, perform meta-analysis, track team progress, and facilitate communication between members. As indicated below, some of these tools are fee-based. You should also bear in mind that not every tool is appropriate for every kind of synthesis or review - be sure to choose the right fit for your project.

Works Cited

Norwich University, 2020. Evidence-based practice guidelines: critical appraisal. Retrieved from

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