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Evidence Based Practice: 5 A's

Critical Appraisal

"Critical appraisal is the process of carefully and systematically examining research to judge its trustworthiness, and its value and relevance in particular context. It is an essential skill for evidence-based medicine because it allows clinicians to find and use research evidence reliably and efficiently" 

Burls, A. (2009). What is critical appraisal? In What Is This Series: Evidence-based medicine. Available online at What is Critical Appraisal?

The basics of Critical Appraisal: 

  1. Validity: measured by research design, method and procedure
  2. Trustworthiness: 
    • Clear statement of findings
    • Precise documentation of results
    • Rigorous data analysis
    • Analysis of how findings fit within established research
  3. Value & relevance: Are results applicable to the clinical question and/or population of interest?

Why is Critical Appraisal Important: 

  • Before applying evidence to a clinical problem it is vital that the researcher critically evaluate: 
    • Study design utilized to determine the research evidence
    • Possible bias and reliability of evidence presented
    • Determine the practical relevance of the research findings

Source: CASP

Critical Appraisal Process

Critical appraisal is a systematic process of analyzing research to determine the strength of the validity, reliability and relevance. 

  1. What is the focus of the study?
    • The focus will address the population, intervention and outcome 
  2. What type of study was completed
    • Is the study design matched with the domain of the research question? 
  3. What are the study characteristics?
    • Use the PICO question format to determine the study characteristics:
      • What are/is the Patient/Population/Problem? How were the participants selected? 
      • What intervention/treatment/test is being studied?
      • Does the study compare the intervention to a control group? 
      • What outcomes are being assessed? Are the outcomes objective, subjective, surrogate? 
  4. How did the researchers address bias within the study?
    • Were the study participants randomly assigned to study groups? 
    • Was the randomization process double or triple blind? 
    • Were the study groups similar at the beginning of the study? 
    • What was the percentage of participant attrition? How many left the study prior to completion? 
    • Apart from the tested intervention, were the groups of the study treated equally? 
  5. What are the study results? Are the results valid?
    • Were the effects of the study provided comprehensively? 
    • What outcomes were measured? Were they clearly specified? 
    • Would the drop out rate effect the study results? 
    • Is there any missing or incomplete data? 
    • Are the potential sources of bias identified? 
    • How large was the treatment/intervention effect? 
    • Do the authors provide access to the raw data? 
  6. Is this study relevant to your population, intervention and outcome
    • Are the results generalizable? 
    • Compare study participants to your population of study. Are the outcome measures relevant? 
    • Is this intervention applicable to your patient/population? (Including patient values)
    • Would this intervention provide greater value to the your patient/population? 
    • Would participant differences alter the outcomes? 
    • Are there limitations in this study that would impact the outcomes desired? 

University of Canberra library. (2021). Module 3: Appraisal. Evidence-based practice in health.

Critical Appraisal Checklists