PHTY211 Lecture Notes - Lecture 5: Cardiothoracic Surgery, Reproducibility, External Validity
Appraising a RCT
• Describe what is meant by the terms:
o Randomisation
o Blinding
o Adequate follow up (drop outs)
o Intention to treat analysis
• Explain the reasons why randomisation, blinding, adequate follow up (drop-outs) and
intention to treat analysis are important when appraising a randomised controlled trial
• Evidence-based Care
o Generating, evaluating and using the best evidence about the way to do the most good t
o people for the least harm
o Integrating the evidence with clinical expertise and applying it to the needs of individual
people
• EBP - critical steps
o Formulate a clinical question from a client's problem
• The best evidence depends on the type of question
▪ What are the phenomena/problems?
• Observation (qualitative research)
▪ What is the frequency of the problem? (frequency)
• Random (or consecutive) sample
▪ Does this person have the problem? (diagnosis)
• Random (or consecutive) sample with Gold Standard
▪ Who will get the problem? (prognosis)
• Follow up or inception cohort
▪ How can we alleviate the problem? (intervention/therapy)
• Randomised controlled trial
• Decision making questions
▪ Q1. What was the aim of the study?
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• To simply describe a population (PO questions) descriptive
• To quantify the relationship between factors (PICO questions)
analytic.
▪ Q2. If analytic, was the intervention randomly allocated?
• Yes? RCT
• No? Observational study
• For observational study the main types will then depend on the timing
of the measurement of outcome
▪ Q3. When were the outcomes determined?
• Some time after the exposure or intervention?
• Cohort study ('prospective study')
• At the same time as the exposure or intervention?
• Cross sectional study or survey
• Before the exposure was determined?
• Case control study ('retrospective study' based on recall of the
exposure)
• Intervention Therapy Question
▪ PICO question
• Population (participants, patients)
• Intervention (exposure or treatment)
• Comparator (control, standard care)
• Outcome (measurement)
o Search the literature for relevant evidence
o Evaluate or critically appraise the evidence for its validity and utility
• The evidence
▪ Dimensions of evidence
• Strength
• Effect size
• Relevance
• Strength
▪ Levels of evidence (hierarchy)
▪ Quality (risk of bias)
▪ Statistical precision (p value +- CI)
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• Filtered evidence
▪ Someone has already objectively appraised the evidence and drawn a
conclusion about the quality and contribution of that
evidence to a particular topic
• Unfiltered evidence
▪ Individual published research articles
▪ Different levels of evidence depending on the research design used
▪ How do you know if it is any good?
• Critical Review of the Evidence
▪ Where is it published?
• Is it a peer‐reieed journal?
▪ Who is on the editorial board (i.e. who is approving this article for
publication)?
▪ When was it published?
▪ Who are the authors
• Where are they from, qualifications, affiliation with an institution, hav
e they published widely on this topic?
o Implement the findings in clinical practice by integrating the evidence with clinical
expertise and client values
o Evaluate the process
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Document Summary
Appraising a rct: describe what is meant by the terms, randomisation, blinding, adequate follow up (drop outs) Follow up or inception cohort: how can we alleviate the problem? (intervention/therapy, randomised controlled trial, decision making questions, q1. What was the aim of the study: to simply describe a population (po questions) descriptive, to quantify the relationship between factors (pico questions) analytic, q2. For observational study the main types will then depend on the timing of the measurement of outcome: q3. Intervention therapy question: pico question, population (participants, patients) Intervention (exposure or treatment: comparator (control, standard care, outcome (measurement, search the literature for relevant evidence, evaluate or critically appraise the evidence for its validity and utility, the evidence, dimensions of evidence. Levels of evidence (hierarchy: quality (risk of bias) Someone has already objectively appraised the evidence and drawn a conclusion about the quality and contribution of that evidence to a particular topic: unfiltered evidence.
