Systematic Reviews: Eligibility Criteria

This guide provides information and resources which may be helpful when undertaking a systematic review or other type of knowledge synthesis.

Eligibility Criteria

“The population, intervention and comparison components of the question, with the additional specification of types of study that will be included, form the basis of the pre-specified eligibility criteria for the review.”1

Types of Criteria

The purpose of a systematic review is to capture & review all literature published on a topic. It is recommended that date ranges be applied only when:

  • You are updating an existing systematic review
  • You are investigating a procedure or intervention that wasn't performed prior to a specific date

Ideally, studies published in all languages should be considered for a review. It is not always practical to translate studies published in other languages, however, so it is acceptable to limit study languages that may be read by the review team.

Study participants may be limited to specific groups of people or age ranges.

  • Researchers may include specific types of study designs and exclude others based on the methodology that best answers the research question.
  • While it may be necessary to include/exclude specific study designs for the review, it is recommended that the team make this determination during title/abstract screening.

Includes interventions of interest and excludes any others.

Studies may be limited to a specific setting, e.g., inpatient, ambulatory, emergency, etc.

  • Quantitative study types are typically included while reviews, editorials, commentaries, and letters are often excluded.
  • Rather than excluding specific publication types at the time of the search, it is recommended that review teams select for their desired publication types during title/abstract screening.

What About Outcomes?

“It is rare to use outcomes as eligibility criteria: studies should be included irrespective of whether they report outcome data, but may legitimately be excluded if they do not measure outcomes of interest, or if they explicitly aim to prevent a particular outcome.”1

References & Recommended Reading

1.         McKenzie J, Brennan S, Ryan R, Thomson H, Johnston R, Thomas J. Defining the criteria for including studies and how they will be grouped for the synthesis. In: Higgins J, Thomas J, Chandler J, et al., eds. Cochrane Handbook for Systematic Reviews of Interventions. version 6.2: Cochrane; 2021.