What is a Systematic Review?

A systematic review is a review of a clearly formulated question that uses systematic and reproducible methods to identify, select and critically appraise all relevant research, and to collect and analyse data from the studies that are included in the review.

A systematic review:

  • Answers a focused research question
  • Employs a comprehensive, reproducible search strategy
  • Identifies ALL relevant studies (both published and unpublished)
  • Assesses all results for inclusion/exclusion, and for quality
  • Presents an unbiased, balanced summary of findings
  • Involves a team of researchers looking at a complex research question
  • Can take months, or even years, to complete.

A systematic review is a tightly structured literature review that focuses on a topic with strict research parameters. The methodology used to collect research has to be consistent in order to reduce misinterpretation and misrepresentation of the data.

To help you understand and conduct your systematic review we have produce LibGuide to help you.

The requirements of a systematic review

  • A clearly defined question: Clarify the key question(s) of your systematic review and the rationale for each question. Use the PICO framework to identify key concepts of the question. Determine inclusion/exclusion criteria.
  • A written protocol: You need to write a protocol outlining the study methodology. The protocol should include the rationale for the systematic review, key questions broken into PICO components, inclusion/exclusion criteria, literature searches for published/unpublished literature, data abstraction/data management, assessment of methodological quality of individual studies, data synthesis, and grading the evidence for each key question.
  • A registered protocol: After you write the protocol, you should register it with PROSPERO, an International Prospective Register of Systematic Reviews. Registration is free and open to anyone undertaking systematic reviews of the effects of interventions and strategies to prevent, diagnose, treat, and monitor health conditions, for which there is a health related outcome.
  • Comprehensive literature searches: First, identify systematic reviews that may address your key questions. Then, identify appropriate databases and conduct comprehensive and detailed literature searches that can be documented and duplicated.
  • Citation management: You should have working knowledge of EndNote or another citation management tool to help manage citations retrieved from literature searches.
  • Follow reporting guidelines: Use appropriate guidelines for reporting your review for publication.

What is a Systematic Literature Search?

A systematic literature search is a literature review on a database (such as Pubmed) which demonstrates that you have compiled a list of appropriate search terms and includes the structure of your search history which provides the evidence on which your research is based.

This is a less rigorous process than a systematic review. A systematic review usually covers a wider scope; you would be expected to look at all the available research in the area in question.

If you are unsure about the differences between a systematic review and a literature review take a look at this guide: The difference between a systematic review and a literature review


There are many different types of reviews, each with its own approach, analysis, and purpose.  You can find more information in the respective section, in the LibGuide

Defining Your Review Question

Consider whether a systematic review is needed before starting your project. Has someone already written one on your topic? Librarians can help you find out. Also decide if you have enough time and resources to conduct a systematic review. Keep in mind that it could take longer than a year complete. Identify a team of collaborators to work with you. This reduces the risk of bias.


PICO may be the most well-known model framework: it has its origins in epidemiology and now is widely-used for evidence-based practice and systematic reviews.

  • PICO normally stands for Population (or Patient or Problem) – Intervention – Comparation – Outcome

Population defines the group you are studying.  It may for example be healthy adults, or adults with dementia, or children under 5 years of age with asthma.

Intervention is the type of treatment you aim to study, e.g. a medicine or a physical therapy.

Comparation is another type of treatment you aim to compare the first treatment with, or perhaps a placebo.

Outcome is the result you intend to measure, for example (increased or decreased) life expectancy, or (cessation of) pain.


Find out more about PICO and other frameworks, in the LibGuide


The protocol serves as a roadmap for your review and specifies the objectives, methods, and outcomes of primary interest of the systematic review. Having a protocol promotes transparency and can be helpful for project management. Some journals require you to submit your protocol along with your manuscript.

The PRISMA guidelines for the transparent reporting of systematic reviews and meta-analyses define a protocol as a document that “describes the rationale, hypothesis, and planned methods of the review. It should be prepared before a review is started and used as a guide to carry out the review”.

For systematic reviews, the PRISMA website provides several sources of guidance on writing a protocol.

Registering or publishing a completed protocol

Once you have written your protocol, consider registering or publishing it. Registration and/or publication improves transparency and prevents unnecessary duplication of research.

For interventions, or accuracy of diagnostic tests:

For social interventions in education, crime and justice, social welfare:

For reviews in health or social care:

For more information about registering protocols & PROSPERO, see:


Need help finding, writing and registering a protocol? See the related section in the Libguide

Reference Management Tools

During the Systematic Literature Review Process, using a Reference Management tool will help you store and organize the citations collected during your screening, de-duplicate the results and automatically format in-text citations and bibliographies in your manuscript.

Systematic Review Support Service

Our librarians help researchers conduct systematic reviews.

How can the Systematic Review Service support you?

As a consultant on your review, we can provide:

  • Evaluating the viability of your topic based on extant literature
  • Assisting in development of a research protocol
  • Identifying databases and grey literature sources
  • Translate strategies for each database
  • Conduct searches in multiple databases
  • Export results to citation management tool, including removal of duplicate records
  • Document search result numbers for PRISMA flow chart and archive search strategies

As a co-author, we can:

  • Assist with question refinement and decisions about methodological approach
  • Developing and refining your review topic
  • Select databases and gray literature sources for searching
  • Design, run and manage database and gray literature searches
  • Assist with deduplication across sources and preparation of the screening project
  • Advise and train the research team on screening methods and software
  • Provide reproducible documentation of the searches for publication
  • Write the search and retrieval portion of the methods section of the paper

Library Trackit

  • Use Library Trackit to send ut your questions or request support with your Systematic Literature Review