A systematic review is a literature review that compiles all available research within a defined research area and answers a specific research question using a particular method.
The entire process of a systematic review, from formulating a research question to developing a protocol, searching the literature, and finally compiling, examining, and analyzing the results, must be conducted according to a carefully planned methodology.
A systematic review is characterized by the following requirements:
• A predefined review protocol
• A precise research question
• A comprehensive literature search
• Accurate documentation
• Quality assessment of the literature
• Involvement of at least two people
Read more about systematic reviews in Cochrane Handbook for Systematic Reviews of Interventions and Joanna Briggs manual for evidence synthesis.
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Types of Reviews:
Are you even supposed to do a systematic review? There are many different types of reviews. The type depends on your research question, your problem statement, the purpose of the review, and the current conditions for conducting the review. See more on AU Library’s page about reviews.
By answering some questions on the Right Review page, you can get guidance on choosing the right type of review.
How much time do you have?:
Completing a systematic review can vary greatly in time, but it often takes between 6 months and 2 years.
How many people?:
It is recommended that at least two people screen, extract data, and assess the quality of articles to avoid risk of bias.
What tools do you have available?:
Consider which tools you will use for your review. At AU/AUH, we provide access to the reference management tool Endnote and the screening tool Covidence.
Does your review already exist?:
Search for your topic in, for example, PubMed or Epistemonikos, which is a database of systematic reviews. Also, consider searching in Prospero to see if a similar review is under development.
A protocol for a systematic review is a detailed plan that outlines the topic, questions, methods, inclusion and exclusion criteria. A protocol is always created before the review itself begins.
PRISMA for systematic review protocols (PRISMA-P) is a checklist you can use to develop a protocol.
Consider whether the protocol should be registered in a public repository. The purpose of registering a protocol is to make your review work visible at the earliest stage. This helps avoid topic overlap and ensures transparency regarding any changes made during the review process, which can help mitigate publication bias.
PROSPERO is a database where you can register protocols for systematic reviews, rapid reviews, and umbrella reviews. The website also provides a checklist for the protocol's content.
Open Science Framework (OSF) is a free, open-source collaboration platform for researchers. You can share publications, data, and ongoing research projects, such as a review protocol.
You can also choose to publish your protocol in a journal that accepts review protocols
UCL Library and Duke University Medical Center Library & Archives list several of these journals.
You can read more about literature searching on the page: Literature search for reviews in health sciences
Since you often have many references to keep track of in a systematic review, it can help to use a reference management tool. If you work at AU or AUH, you have access to EndNote. You can get help and guidance with EndNote at one of our open EndNote courses, by booking a meeting with us, or by gathering a small group – we're happy to come and hold an EndNote course for you. You can find guidance on using EndNote via Citrix here. (in danish)
There are also free reference programs that offer many of the same features as EndNote. Some of the most common ones are Mendeley and Zotero. The library do not support these systems the same way we support EndNote, but if you want to use one of them (for example, because your collaborators or colleagues use it), you'll find plenty of help online.
In the screening process, you review all retrieved articles to select those that meet the predefined inclusion and exclusion criteria. Using a screening tool can help systematize the review of articles. For systematic reviews, it is generally required that two reviewers independently screen all articles.
AU/AUH subscribes to the web-based screening tool Covidence. Covidence assists in managing the literature selection process, preventing confusion in sorting, ensuring blinding between reviewers, and removing duplicates.
Employees and students at AU and AUH can gain institutional access to Covidence. To obtain access, send your AU/AUH email and name to Anne (anvm@kb.dk), Helene (hso@kb.dk), or Karen (kts@kb.dk).
Others can use a "free trial," which is limited to one review with a maximum of 500 references.
Check Covidence’s own knowledge base for assistance.
There are several other screening tools tailored to different needs. In this comparison of screening tools for reviews, you can explore various options to find a screening tool that suits your review and working method.
One of the requirements for a systematic review is the use of established standards for assessing the quality of the included studies (critical appraisal).
There are various checklists available, depending on the study design used in the research article.
For more information, see the University of Copenhagen Library's resources on systematic reviews and the special issue of Ugeskrift for Læger 2024/12: "A Guide to Critical Reading of Research Articles."
If you need assistance with your systematic review, please feel free to contact us. Specifically, we can help with the following parts of the review process:
Selection of relevant databases
Translating the focused question into a search strategy
Translating the search strategy to different databases
Guidance on using EndNote
Guidance on using Covidence
Documentation of the search strategy, e.g., PRISMA
Updating the search
We are happy to answer questions via both email and phone.
Additionally, you can book a meeting with us, which can be held at AU Library, Health Sciences, or Aarhus University Hospital.
See all contact details on the pages for AU Library, Health Sciences, Library Services for AUH.
We also have a booking form for systematic review assistance, which you are welcome to use. It can be found on our page for literature search support.
