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Systematic Reviews in the Health Sciences

A guide to systematic reviews in the health sciences.

Before Creating a Protocol:

Before beginning to write a protocol, check if others have registered a systematic review protocol on your topic. Check the Cochrane Database of Systematic Reviews, which is a database licensed by the UCalgary, and PROSPERO, an international prospective register of systematic reviews that is freely available online.

If you find that your research question is unique, that is when you can go ahead and develop your protocol or research plan. A protocol includes a research question, inclusion and exclusion criteria, databases and keywords to search, a coding system for data extraction, and a plan for data management. A common format for a protocol can found through PROSPERO.

What Does a Protocol Need?

A protocol includes 5 specific items: 

  • A specific research question
  • Inclusion and exclusion criteria
  • Databases and keywords to search
  • Coding system for data extraction
  • Data Management Tools

Published protocols are important because they hold you accountable to what you originally set out to do and journals are increasingly requiring that you have a published protocol before you begin your review. It helps answer questions at the beginning so you don’t get stuck somewhere down the line.

A Specific Research Question

A research question for a systematic review must be specific and focused. You can usually break down your question into key concepts using the PICO(S) framework.

  • Population (or patient or problem)
  • Intervention (or exposure)
  • Comparison (or control)
  • Outcome(s)
  • Study design

PICO works best for clinical questions, but there are alternative question frameworks if you find your question doesn’t fit the PICO framework. The below paper discusses other frameworks that could work for your topic if PICO does not. 

  • Booth A, Noyes J, Flemming K, Moore G, Tunçalp Ö, Shakibazadeh E. Formulating questions to explore complex interventions within qualitative evidence synthesis. BMJ Global Health. 2019 Jan 25;4 (Suppl. 1):e001107.

Inclusion and Exclusion Criteria

Another key part of your protocol is identifying inclusion and exclusion criteria for the studies you’ll find. This must be done before you conduct your search and the criteria you identify will be determined by your research question. The idea behind inclusion and exclusion criteria is that they clearly define what subjects or studies will be included in your review. They are essential for determining which of your search results are relevant or irrelevant.

Some examples of possible inclusion and exclusion criteria for systematic reviews include: 

  • Specific interventions or treatments
  • Study Design (examples: case studies, RCTs, opinion pieces)
  • Geographic regions
  • Language
  • Publication date
Databases and Keywords to Search
Listing your databases and keywords in your protocol illustrates you've thought about how to search. This is part of your methodology and illustrates how you will be doing data collection. This includes thinking about: 
  • Keywords of your concepts
  • Synonyms/antonyms of your concepts
  • Where you'll be searching (databases, indexes, key journals) 
  • Contacting authors in your field 
  • Grey literature sources (preprints, conference proceedings, dissertations, periodicals) 
  • Publications from relevant organizations 

Coding system for data extraction

Identifying a plan of what you are going to do with the collected data at the protocol stage saves time later on in the process. Coming up with a synthesis plan by pre-scanning the literature and locating seed papers to see their keywords and subject headings helps you understand what you'll want to pull out and code during data extraction. This can be done using a standardized extraction formula. 

The librarians at the University of Toronto have identified great resources on data extraction. The University of Calgary Library does not provide support on data extraction or synthesis; please reach out to the Student Success Centre for support of data synthesis.  

Data Management Tools

There are many data management tools for you to use as part of your process. You can save your citations using a software program like Zotero (free) or Endnote (can be purchased through the Medical bookstore). As a member of the University of Calgary, you have access to Covidence which can be used to both screen and extract data. 

The PRISMA checklist, specifically for protocols, is a 27-item checklist that outlines exactly what you need to include within your protocol. You can access the full checklist on their website,