Skip to Main Content

Study Skills

Systematic Reviews: Screening

Screening software

Referencing software such as Endnote (link opens in new window), EndnoteWeb (link opens in new window), Mendeley (link opens in new window) or Zotero (link opens in new window).

Systematic review screening software such as Covidence (requires you or your department to purchase a subscription; link opens in new window) or Rayyan (most features free; link opens in new window). There is a good guide to using Rayyan (link opens in new window) produced by Carrie Price, Health Professions Librarian at Towson University.

Our top tips guides and tutorial videos (link opens in new window) will help you use these various pieces of software. The Medical Library also runs training sessions on using referencing software:

  • Endnote (link opens in new window)
  • Mendeley (link opens in new window)
  • Zotero (link opens in new window)

Best practice for screening

Screening large numbers of articles can be complicated and time-consuming. It is a good idea to establish a well-structured, clear process for all reviewers to follow. This journal article: Best practice guidelines for abstract screening large-evidence systematic reviews and meta-analyses(link opens in new window) suggests some best practice processes to follow when screening for a systematic review.

'Too many' results?

Systematic review searches will typically yield thousands, or even tens of thousands of search results. Of these, it is likely only a small handful will be relevant and ultimately included in the review. This journal article:  Precision of healthcare systematic review searches in a cross-sectional sample (link opens in new window) finds that on average most systematic reviews only include 3% of all results found in the search, with the majority being discarded at the screening stage. This is why it's so important to have robust screening criteria, and a well-organised system for doing the screening.


After you have completed your database and grey literature searches, and identified other papers through hand-searching, you will need to screen the titles and abstracts to determine if they meet the criteria for inclusion. These criteria should be pre-defined (i.e. stated in your protocol before you begin the searches). Inclusion criteria might relate to the following:

  • Date range of publication
  • Study design type
  • Whether a study focuses on your specific disease, condition, or patient population
  • Whether a study focuses mainly on your specific intervention
  • Whether a study took place in a certain country or hospital context

This list is not exhaustive, and there are many other inclusion criteria you may wish to use. It is important that they are stated clearly in the Methods section of your protocol and systematic review, and that all co-authors understand them.

Generally articles are screened against these criteria independently by at least two authors. Initially you should screen the titles and abstracts, which will leave you with three groups of articles: Include (those which meet all inclusion criteria), Exclude (those which do not meet at least one of the inclusion criteria) and Doubt (those for which it is unclear from their title and abstract if they meet all inclusion criteria). Once you have screen the titles and abstracts in this way, the full text for each article in the Doubt group should be obtained, and the same procedure applied. Therefore, at the end of the screening process you will be left with two groups of articles: Include, and Exclude.





PRISMA flow diagram

When writing up your systematic review, you will need to include a flow diagram indicating the number of papers found, and the number removed after various stages of screening. There is a standard PRISMA template for this diagram, and an online tool (link opens in new window) you can use to generate PRISMA flow diagrams.

Contact us

Profile Photo
Medical Library Team
University of Cambridge Medical Library
Box 111
School of Clinical Medicine
Cambridge Biomedical Campus
Subjects: Clinical Medicine

Cochrane Crowd

Image credit: Pezibear on Pixabay.

Cochrane Crowd (link opens in new window) is a 'collaborative volunteer effort to help categorise and summarise healthcare evidence so that we can make better healthcare decisions.' Get involved if you want to gain experience in the systematic review process without committing to a full scale systematic review immediately.

© Cambridge University Libraries | Accessibility | Privacy policy | Log into LibApps