After databases (and any other sources) have been searched, and duplicates removed, the next step is to select the papers that will go on to be included in your review project. This selection phase is also known as screening.
Firstly the title and abstract of the citations are checked by two reviewers independently to decide whether each citation should be included or excluded (this is often called title/abstract screening). The process for resolving any disagreements should be specified before beginning this phase.
The citations which are included from the title/abstract screening step go on to the next stage, full text screening. The full text of these papers is obtained, and they are again checked for inclusion or exclusion according to the review criteria. At this stage having the full text of the paper available enables a final decision to be made for each paper. The papers included at this stage are the ones that will be included in the review (i.e. they are the ones that will have data extracted from them if this is a project that will synthesise the data from multiple papers).
The numbers of citations included and excluded for this process need to be recorded for the review. There is a free tool called the PRISMA flow diagram which is commonly used to demonstrate the process of inclusion and exclusion and to record the numbers of references. For reviews to be PRISMA compliant they must also adhere to the other requirements presented at that website. The PRISMA flow diagram is available from the PRISMA statement website:
NOTE: 1/3/23 - The PRISMA website is currently offline. The PRISMA checklist and expanded checklist can be downloaded as supplementary materials to this article. Other materials may be available via the articles listed on the EQUATOR website.
Rethlefsen ML, Page MJ. PRISMA 2020 and PRISMA-S: common questions on tracking records and the flow diagram. J Med Libr Assoc. 2022;110(2):253-7.
UQ Library subscribes to Covidence - an online software product designed to improve the efficiency and experience of creating and maintaining systematic reviews. Covidence will help you with the selection (screening) and extraction phases of your project.
The following resources will help you navigate Covidence: