UPDATED: November 17, 2025. Original Post: July 20, 2020

Integrating the best available health evidence into decision-making processes is an important part of evidence-based practice. However, before applying clinical research findings to patient care, health care providers must determine whether the research findings are valid.

It is important to remember that published studies are not necessarily trustworthy. Healthcare research must be evaluated before being used to guide clinical decisions. Critical appraisal provides a framework for this evaluation.

What is critical appraisal?

Critical appraisal is “the process of carefully and systematically examining research to judge its trustworthiness, and its value and relevance in a particular context.” (CASP)

To critically appraise clinical research is to look at its methodological quality, trustworthiness, and applicability to a patient’s specific situation. Critical appraisal helps us ask two essential questions about a particular research study (Sala Serra & Domingo Torrell, 2022):

  • Are the results believable and free of bias or errors? (internal validity)
  • Do the results apply to populations other than the sample participants, specifically to my patient’s situation? (external validity)

When should critical appraisal be conducted?

Research should always be critically appraised, no matter its intended use. Such uses may include:

  • Patient care in a clinical setting
  • Organizational policies or guidelines
  • Care directives
  • Educational projects

For example, if a recently published study in your discipline suggests a therapy is effective and safe for patients, critically appraising the study ensures the findings are valid and unbiased, and the therapy is appropriate for the specific needs of your patient.

Beyond clinical scenarios, critical appraisal is also a key part of evidence synthesis. As part of the systematic review process, for example, articles included in the review are critically appraised for validity. This ensures that the integrity of the overall review is not impacted by the quality of the individual studies included.

Using critical appraisal checklists

Any type of clinical study can be critically appraised, and each study type has its own checklist. Critical appraisal checklists provide a step-by-step guide through the appraisal process. There are many critical appraisal tools available from organizations that are experts in evidence-based research evaluation, including:

For example, CASP’s Randomised Controlled Trial Checklist includes questions about study methodology such as:

  • Was the assignment of participants to interventions randomised?
  • Were the investigators ‘blind’ to the intervention they were giving to participants?
  • Do the benefits of the experimental intervention outweigh the harms and costs?
  • Would the experimental intervention provide greater value to the people in your care than any of the existing interventions?

Critical appraisal for antiracism is rarely addressed in standard tools. To avoid overlooking underrepresented patient populations, consider supplementing your chosen tool with Naicker’s Critically Appraising for Antiracism Tool.

Critical appraisal can be conducted without the use of a formal checklist, but using an established set of appraisal criteria may be helpful if you want to ensure that you are consistent in how you appraise clinical research.

For more info on critical appraisal in your daily work or a larger project, email AskLibrary@nshealth.ca or book a one-on-one consultation with a librarian.

Additional Support

In-depth Resources in Library Services' Searching subject guide.

References

1. CASP - Critical Appraisal Skills Programme. (2025, October 15). What is critical appraisal?. https://casp-uk.net/what-is-critical-appraisal/

2. Naicker, R. (2022). Critically appraising for antiracism. Education for Information, 38(4), 291–308. https://doi.org/10.3233/EFI-220052

3. Sala Serra, M., & Domingo Torrell, L. (2022). Validity of a study: Internal and external validity. Cirugia espanola, 100(10), 649–651. https://doi.org/10.1016/j.cireng.2021.12.007

Selena MacDonald

Librarian Educator
Nova Scotia Hospital, Central Zone