After you've conducted your searches and exported all your results into a reference manager, you can start screening articles. During this step, reviewers select which studies are relevant based on their inclusion and exclusion criteria.
To control bias and minimise the risk of excluding relevant studies, screening is usually done by two or more independent reviewers. They talk through any disagreements in decision making over study inclusion or exclusion.
A standard workflow for this stage might be:
The PRISMA flow diagram visually summarises the screening process. It makes the selection process transparent and clear to the reader by reporting on decisions made at various stages of the systematic review. When you're excluding articles at the full-text stage, you need to specify the reasons for exclusion. It's important to document this thoroughly.
Pre-screening: Record the numbers of results from each database or source recorded before screening commences
Deduplication: Remove duplicated articles from the combined result set.
Title/abstract screening: Each reviewer will need to read titles and abstracts to see if they match the inclusion/exclusion criteria or have some value to the systematic review. This is done separately by each reviewer to ensure minimal bias. Results are then compared.
Full-text screening: Included articles are located in full-text prior to multiple reviewers individually read through the full-text of included articles to fine-tune the final collection of articles that will contribute to the review.
When reviewing the final search results from your chosen databases (and other sources if relevant), multiple reviewers (you and your supervisors or co-reviewers) will make decisions on which articles to include and exclude based on the criteria specified in your protocol. The first stage of this is usually based on titles and abstracts, then a full text analysis follows before data extraction.
Use EndNote to store and screen references. EndNote is useful for the initial title/abstract screen and sourcing articles required for the full-text screening process.
Rayyan is a freely available program that helps screen studies for a systematic review by automatically identifying disagreements and allowing the use of keywords to help identify relevant studies. Rayyan also has a mobile app for iPhone, iPad and Android devices.
Systematic Review management software. While this software is not supported by the library, you can sign up for a trial review of under 500 articles for free or to purchase a yearly licence.
The Centre for Evidence-Based Medicine offers some simple advice for starting the process of critical appraisal:
"Critical appraisal is the systematic evaluation of clinical research papers in order to establish:
If the answer to any of these questions is “no”, you can save yourself the trouble of reading the rest of it."
There are various critical appraisal tools available to assist you with this process: