From the Cochrane Handbook for Systematic Reviews of Interventions:

"A systematic review attempts to collate all the 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 (Antman et al 1992, Oxman and Guyatt 1993)...This involves: the a priori specification of a research question; clarity on the scope of the review and which studies are eligible for inclusion; making every effort to find all relevant research and to ensure that issues of bias in included studies are accounted for; and analysing the included studies in order to draw conclusions based on all the identified research in an impartial and objective way"

Lasserson TJ, Thomas J, Higgins JPT. Chapter 1: Starting a review. In: Higgins JPT, Thomas J, Chandler J, Cumpston M, Li T, Page MJ, Welch VA (editors). Cochrane Handbook for Systematic Reviews of Interventions. Version 6.0 (updated July 2019). Cochrane Collaboration; 2019.  http://www.training.cochrane.org/handbook

Consider the following questions before you begin a systematic review. 

1. Is your question suited to a systematic review?

While a systematic review is considered the highest form of evidence, not all questions are suited to a systematic review. A question that is well suited to this methodology is:

• based on a specific question or patient problem and will ensure that your search produces relevant results.
• narrow enough that identifying and reviewing all of the relevant literature is possible. An extremely broad question (e.g. examining pain management and assessment) may be more suited to a general literature review or scoping review.
• broad enough that you will be able to find some relevant literature.  An extremely narrow topic (e.g. an examination of a very small subset of a population) or one that is examining a very new treatment or concept may not return enough relevant literature for a systematic review to be able to draw any meaningful conclusions.
• defined with some consistency across the literature. A question with a multi-stepped intervention, or one in which different elements of an intervention may or may not be included in each study may be more suited to a different approach.

2. Are you asking a clearly defined question?

Thinking about your PICO (population, intervention(s), comparator(s), and outcomes) will help to ensure that you have thought of the important parts of your question, are not omitting any key concepts from your strategy, and assist you in developing your inclusion/exclusion criteria. You can use our PICO worksheet to help develop and refine your question and keywords for your search. 

3. Has a recent systematic review already addressed this exact question?

Before starting your systematic review, you should check for recently published or upcoming reviews on your topic to avoid duplication of effort. Please contact the Ebling Library Systematic Review team if you need assistance searching for existing systematic reviews and registered protocols. 

4. Do you have the time and resources needed to conduct a systematic review?

The mean estimated time to complete and publish a systematic review is 1.3 years, according to a 2017 study. Input from at least 3 team members is needed, in addition to advice or input from a librarian or team member who is experienced in searching the literature. Team members should include someone to oversee the review process, a subject specialist to help decrease the potential for bias to enter your research, and a third team member to break a tie in case of disagreement. 

5. Can you meet all of the requirements for a systematic review detailed in the PRISMA checklist?

The PRISMA group created a checklist of items for systematic review protocols that should be followed to ensure thoroughness and transparency in reporting. You should consider registering your protocol with PROSPERO to allow for peer review and to avoid duplication of effort. 

This guide was adapted with permission from University of North Carolina Libraries.