Systematic Reviews Legacy Guide: Study Selection (Screening)

Once you have completed literature searching and compiled all citations, it is time to screen the results. The purpose of screening is to eliminate studies that do not meet your inclusion criteria. Two independent reviewers should screen all studies, starting with a title and abstract screening, followed by a full-text screening. A third reviewer should resolve any conflicts. 

One of the most important aspects of screening citations is to make sure the team adequately understands how to properly apply the inclusion and exclusion criteria to the citations being screened. It can be especially helpful for screeners to undertake preliminary/test screening on a subset of articles to ensure agreement. Test screening can be performed in Covidence or Excel. While adding this step may add some time initially, it will most likely expedite both screening phases after as screeners will be more comfortable applying the inclusion and exclusion criteria properly and most likely result in less error or conflicts.

"PRISMA stands for Preferred Reporting Items for Systematic Reviews and Meta-Analyses. It is an evidence-based minimum set of items for reporting in systematic reviews and meta-analyses. The aim of the PRISMA Statement is to help authors improve the reporting of systematic reviews and meta-analyses. The PRISMA Statement consists of a 27-item checklist and a four-phase flow diagram." (From prisma-statement.org )

In your review, you will need to track the number of results from each database you search, the number of duplicates you remove, the decisions you make on each article, and in the full text level, the reasons why you exclude articles. More information and a step-by-step guide can be found on the Using PRISMA for Reporting page on this guide.

There are many tools that can be useful for organizing the screening process including Covidence, Rayyan, Abstrackr, and HAWC.   

UNC currently has an institutional subscription to Covidence making it available for free to UNC-affiliated users. HSL can provide classes and support for Covidence. To learn more visit the Covidence LibGuide. HSL does not currently offer in-house support for other screening tools; however, links to training materials are provided directly below.  

All of these tools support reference importing of multiple file types (.ris & txt), in-/excluding references, exporting results, and tagging with keywords. Additionally, they are all web-based and therefore can be used on a mac or pc. They cannot assist with protocol development or automated searching. The chart below provides more details to help you compare and choose a screening tool.

The table compares Covidence, Rayyan, Abstrackr, and HAWC (from left to right) based on a number of features.

Feature:	Covidence	Rayyan	Abstrackr	HAWC
Logo
Cost	UNC has a subscription to Covidence	Free	Free	Free
Support available at UNC HSL	Yes	No	No	No
Quality Assessment	Yes	Yes	No	Yes
Data Extraction	Yes	Yes	No	Yes
Allows Multiple User Support	Yes	Yes	No	No
Reference Allocation	Yes	Yes	Yes	No
Multiple Screening Phases	Yes	No	No	No
Discrepancy Resolving	Yes	Yes	Yes	No
Show Project Progress	Yes	Yes	Yes	No
Attaching Comments	Yes	No	Yes	No
Attaching PDFs	Yes	Yes	No	Yes
Keyword Highlighting	Yes	Yes	Yes	No
Deduplication	Yes	Yes	No	No
PRISMA Diagram	Yes	No	No	Yes
Interrater Reliability	Yes	Yes	No	No
Mobile Friendly Version	Yes	Yes	No	No
Export Results File Types	RIS, CSV, TXT	RIS, BibTex, CSV, EndNote	RIS, CSV, XML	XLSX

If the tools above don't meet your needs, you can also try this Excel tool called the VonVille Method.  

Information about screening tools and features:Van der Mierden, S., Tsaioun, K., Bleich, A., & Leenaars, C. H. C. (2019). Software tools for literature screening in systematic reviews in biomedical research. ALTEX : Alternativen zu Tierexperimenten, 36(3), 508-517.