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Systematic Reviews: Home

Created by Health Science Librarians

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What is a Systematic Review?

What is a Systematic Review?

A systematic review is a literature review that gathers all of the available evidence matching pre-specified eligibility criteria to answer a specific research question. It uses explicit, systematic methods, documented in a protocol, to minimize bias, provide reliable findings, and inform decision-making. ¹ ²


There are many types of literature reviews.

Before beginning a systematic review, consider whether it is the best type of review for your question, goals, and resources. The table below compares a few different types of reviews to help you decide which is best for you. 

Comparing Systematic, Scoping, and Systematized Reviews
Systematic Review Scoping Review Systematized Review
Conducted for Publication Conducted for Publication Conducted for Assignment, Thesis, or (Possibly) Publication
Protocol Required Protocol Required No Protocol Required
Focused Research Question Broad Research Question Either
Focused Inclusion & Exclusion Criteria Broad Inclusion & Exclusion Criteria Either
Requires Large Team Requires Small Team Usually 1-2 People

A simplified process map

Systematic Reviews: A Simplified, Step-by-Step Process  Step 1: Pre-Review. Common tasks include formulating a team, developing research question(s), and scoping literature for published systematic reviews on the topic. Librarians can provide substantial support for Step 1.  Step 2: Develop Protocol. Common tasks include determining eligibility criteria, selecting quality assessment tools and items for data extraction, writing the protocol, and making the protocol accessible via a website or registry.  Step 3: Conduct Literature Searches. Common tasks include partnering with a librarian, searching multiple databases, performing other searching methods like hand searching, and locating grey literature or other unpublished research. Librarians can provide substantial support for Step 3.  Step 4: Manage Citations. Common tasks include exporting citations to a citation manager such as Endnote, preparing a PRISMA flow-chart with numbers of citations for steps, updating as necessary, and de-duplicating citations and uploading them to a screening tool such as Covidence. Librarians can provide substantial support for Step 4.   Step 5: Screen Citations. Common tasks include screening the titles and abstracts of citations using inclusion criteria with at least two reviewers and locating full-text and screen citations that meet the inclusion criteria with at least two reviewers.  UNC Health Sciences Librarians (HSL) Librarians can provide support with using AI or other automation approaches to reduce the volume of literature that must be screened manually. Reach out to HSL for more information.  Step 6: Conduct Quality Assessment. Common tasks include performing quality assessments, like a critical appraisal, of the included studies.  Step 7: Complete Data Extraction. Common tasks include extracting data from included studies and creating tables of studies for the manuscript.  Step 8: Write Review. Common tasks include consulting the PRISMA checklist or other reporting standard, writing the manuscript, and organizing supplementary materials. Librarians can provide substantial support for Step 8.

How can the library help?

The average systematic review takes 1,168 hours to complete.¹ 
A librarian can help you speed up the process.

Systematic reviews follow established guidelines and best practices to produce high-quality research. Librarian involvement in systematic reviews is based on two levels. In Tier 1, the librarian will collaborate with researchers in a consultative manner. In Tier 2, the librarian will be an active member of your research team and co-author on your review. Roles and expectations of librarians vary based on the level of involvement desired. Examples of these differences are outlined in the table below.

Role Tasks Tier 1: Consultative Tier 2: Research Partner / Co-author
Topic Development Guidance on process and steps Yes Yes
  Background searching for past and upcoming reviews Yes Yes
Development of Eligibility Criteria Development and/or refinement of review topic Yes Yes
  Assistance with refinement of PICO (population, intervention(s), comparator(s), and key questions Yes Yes
  Guidance on study types to include Yes Yes
Protocol Creation and Registration Guidance on protocol registration Yes Yes
Searching Identification of databases for searches Yes Yes
  Instruction in search techniques and methods Yes Yes
  Training in citation management software use for managing and sharing results Yes Yes
  Development and execution of searches No Yes
  Downloading search results to citation management software and removing duplicates No Yes
  Documentation of search strategies No Yes
  Management of search results No Yes
Study Selection and Extraction Guidance on methods Yes Yes
  Guidance on data extraction, and management techniques and software Yes Yes
Writing and Publishing Suggestions of journals to target for publication Yes Yes
  Drafting of literature search description in "Methods" section No Yes
  Creation of PRISMA diagram No Yes
  Drafting of literature search appendix No Yes
  Review other manuscript sections and final draft No Yes
  Librarian contributions warrant co-authorship No Yes

Systematic reviews in non-health disciplines

Researchers are conducting systematic reviews in a variety of disciplines.  If your focus is on a topic other than health sciences, you may want to also consult the resources below to learn how systematic reviews may vary in your field.  You can also contact a librarian for your discipline with questions.


Environmental Topics

Social Sciences

Social Work

Software engineering

Sport, Exercise, & Nutrition

Resources for performing systematic reviews

Updating reviews

Looking for our previous Systematic Review guide?

Our legacy guide was used June 2020 to August 2022