What is screening?

The process of reviewing your search results and removing (or setting aside) the studies that do not meet your inclusion criteria. 

Why screen your results?

Even a well-designed, efficient search strategy will return some results that are less relevant to your research question. The more sensitive your search strategy, the more results you will get.

When to screen your results

When you perform a systematic and sensitive literature search, you will need to screen the results in order to find the most relevant literature. Allow additional time for screening results if you are undertaking any of the following:

• Literature reviews
• Systematic reviews and/or meta-analyses -- these require a formal, documented screening process
• Searches/questions that require thoroughness and analysis of the search results
• Multifaceted clinical queries with broad and complex concepts, such as, "What practices prevent transmission of infections from the hospital environment onto healthcare workers' clothing and the personal items they bring to work?"

If you are conducting a quicker, more precise search, you may be able to screen in a more informal and unstructured way -- for example, by scanning through a list of results to find the most relevant title(s). Circumstances in which this approach would be appropriate include:

• When looking for a recent review on a specific condition or topic
• Clear questions with singular, simple concepts. For example, "What is the recommended dosage of paracetamol for a child with fever?"
• To locate a couple of key articles to stimulate further discussion in a journal club.

How to screen

• Before you begin, ensure that you have deduplicated the results of your literature search. 
• Establish a screening workflow based on any tools or software that you will use, such as Covidence or Excel. E.g. if you are using Excel, will you use multiple spreadsheets? How will you indicate which studies are included, and which require a closer look? If you are working with others to screen the results, document a clear step-by-step process. 
• Keep a list of your inclusion and exclusion criteria nearby -- if in doubt, refer back to it.
• It can be quicker and easier to focus first on excluding the clearly irrelevant results. 
• Initially, screen your results by title and abstract. If the title and/or abstract are not relevant to your research question, exclude the paper.
• If a paper's relevance is not clear from its title and abstract, review the full text before making a decision about including or excluding it.

Covidence User Guide

Note: When performing a systematic review or meta-analysis you are required to document the process and results of screening and selecting studies. For more details see the Cochrane Handbook and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement.

Cochrane Handbook

PRISMA Statement