Literature searching: searching in a systematic way

Screening is the process of selecting the studies that you will include in your literature review. Ideally, screening should be done by two reviewers who are blinded ie they cannot see each others decisions). Use the inclusion and exclusion criteria set when the defining the question. The process usually involves two steps:

1. First Screening is based on Title/Abstract.   
2. Second Screening is based on the Full Text of the remaining articles.   

It is very important to keep track of the number you exclude at each level. Use the PRISMA flowchart to record the number of records excluded at both title/abstract screening and full text screening.  For full text screening, the reasons for excluding each paper must be included. 

Screening will be based on the inclusion/exclusion criteria that you have set when developing your question. You may introduce bias into the final review if these are not used consistently.

It is a good idea to go through your inclusion/exclusion criteria with your screening collaborator and agree on a list to be used for screening. You might also want to agree on a list of terms that you would like to see highlighted (green for inclusion terms, red for exclusion) in your screening tools.

Rayyan is a free, web-based tool that is highly recommended for screening at both the title/abstract and full-text level. Keep in mind:

• It offers a blinding option when shared with other reviewers.  
• It offers deduplication
• Once the title/abstract screening is complete, you will need to copy your included abstracts into a new review, where you can upload PDFs of the full text for the next round of screening.