Systematic Reviews and Literature Reviews

Systematic reviews are considered the gold standard of evidence synthesis. A systematic review does not just mean a literature review that has been conducted systematically. A systematic review is a specific type of research methodology that has its own set of standards and methods. Systematic reviews are typically written with a team and include protocols or rules on how they are conducted. UNCG librarians can help you learn more about systematic reviews, so be sure to contact your liaison librarian for assistance. 

UNCG Libraries Systematic Review Guide

This page was modified from the USC Libraries Choosing Evidence tutorial. 

Systematic literature reviews are at the top of the levels of evidence pyramid, but other literature reviews are not. Literature reviews, traditional literature reviews, or narrative literature reviews are considered expert or consensus opinion.

	Systematic Review	Literature Review
Definition	Identifies, selects, appraises, and synthesizes all research evidence related to that question.	Qualitatively summarizes evidence on a topic using informal or subjective methods to collect and interpret studies.
Goals	Answer a focused clinical question Eliminate bias Provide a secondary analysis of existing research	Provide summary or overview of topic
Question	Clearly defined and answerable clinical question Recommend using PICO as guide	Can be a general topic or a specific question
Components	Pre-specified eligibility criteria Systematic search strategy Assessment of the validity of finding Interpretation and presentation of results Reference list All components are tested, turned into a protocol that is shared and finalized before the full review is carried out	Introduction Methods  Discussion  Conclusion Reference list May include systematic review components such as eligibility criteria but it is acceptable to adjust these as needed during any part of the project
Number of Authors	Three or more	One or more
Timeline	Months to years Average 18 months	Weeks to months
Requirements	Thorough knowledge of topic Perform searches of all relevant databases  Additional searching and browsing to find all published and unpublished research on the question  Use a checklist or similar tool to standardize the appraisal of research studies Statistical analysis resources (for meta-analysis)	Understanding of topic Perform searches of one or more databases
Value	Connects practicing clinicians to high quality evidence Supports evidence-based practice	Provides summary of literature on a topic

Table modified from USC Libraries Choosing Evidence tutorial

For more information about literature reviews: UNCG Libraries Literature Review Module

When searching for systematic reviews, you can usually spot a systematic review by the title. 

• The title of a systematic review should include “systematic review,” or “meta-analysis,” or even “systematic review and meta-analysis.”
• Some health science databases, such as PubMed, have a filter that includes “systematic reviews.”
• The title of a literature review will include “literature review” or "narrative review," and sometimes just “review.”
• Keep an eye out for scoping reviews or integrative reviews. These are other literature reviews that find and synthesize evidence, but they are not systematic reviews. 
• Keep an eye out for systematic review protocols. These are the blueprint/plan for conducting a systematic review but not the completed systematic review. 

If creating a systematic review, keep in mind that systematic reviews are different from literature or narrative reviews. A systematic review addresses a "...clearly formulated question that uses systematic and explicit methods to identify, select and critically appraise relevant research, and to collect and analyze data from the studies that are included in the review." (Cochrane Handbook). Because of this, the time commitment for a systematic review is significant, please plan ahead and be sure to leave enough time to work on your review.

 

                   Month                 Activity

                   1 – 2                     Preparation of protocol.

                   3 – 8                     Searches for published and unpublished studies.

                   2 – 3                     Pilot test of eligibility criteria.

                   3 – 8                     Inclusion assessments.

                   3                          Pilot test of ‘Risk of bias’ assessment.

                   3 – 10                   Validity assessments.

                   3                          Pilot test of data collection.

                   3 – 10                   Data collection.

                   3 – 10                   Data entry.

                   5 – 11                   Follow up of missing information.

                   8 – 10                   Analysis.

                   1 – 11                   Preparation of review report.

                   12 –                      Keeping the review up-to-date.

Source: Higgins JPT, Green S (editors). Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0 [updated March 2011]. The Cochrane Collaboration, 2011. Available from www.cochrane-handbook.org.

From East Carolina University’s Systematic Review LibGuide

A meta-analysis is a statistical analysis of quantitative data sometimes included in systematic reviews that combine studies, such as randomized controlled trials (RCTs), with quantitative and comparable data.

Image from USC Libraries Choosing Evidence tutorial

More guides on systematic reviews:

NIH Systematic Reviews Guide

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