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A Guide to Critical Appraisal of Health Research

Appraising Intervention Studies: Some Basic Questions

When evaluating a paper reporting on an intervention study, here are a basic questions to consider:

  • Is the study that the author(s) are reporting on a Randomized Clinical Trial (RCT)?
  • Were patients randomly assigned to treatment groups?
  • Was this randomization concealed from the clinicians in order to reduce bias?
  • Did the members in each study group have a similar prognosis at the start of the trial?
  • Was patient follow-up long enough and complete?
  • Were all the patients analyzed within the group they were assigned?
  • What is the magnitude of the treatment effect? (see the box below for information on how to calculate the treatment effect)


Straus, S. (2011). Evidence-based medicine : How to practice and teach it. (4th ed. / Sharon E. Straus ... [et al.].. ed.). Edinburgh: Elsevier Churchill Livingstone.

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