Evidence-Based Medicine in
Clinical Practice.
Dr. Harry Gee
Dr. Chisale Mhango
ETATMBA Module 5
"Every intervention is a twoedged sword."
Iain Chalmers
ETATMBA Module 5
Practice Pradigms
Old paradigm
New paradigm
Unsystematic
clinical experience
Systematic clinical
experience
Pathophysiology
Pathophysiology
necessary but not
sufficient
Content expertise
& authoritarianism
Rules of evidence
Pre-Requisites
• Questioning
– The Knowledge Gap
– Honesty
– Humility
– Discerning
• What is merely custom and
practice?
• Desire for Improvement
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Our Aims
• Understand EBM
– What is it?
– Why do we need it?
– What are the benefits?
– Who benefits?
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Our Objectives
The key steps:
– Formulate a clinical question
– Search the literature
• Efficiently
• Confidently
– Appraise the evidence
– Apply the evidence
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What is EBM?
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Good Clinical Practice
• Knowledge from best external evidence
based on clinical research
• Judgement from experience.
• Understanding of patient's beliefs &
preferences.
Sackett 1996
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Who Benefits?
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Evidence Based Medicine
Conscientious, explicit and judicious
use of current best evidence in
making decisions about the care of
an individual patient
Sackett. BMJ 1996;312:311-2
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EBM for the Clinician
• Knowledge & Skills
• Proficiency
– Application
– PRACTICE
– Confidence
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The 5 Steps Towards
Evidence Based Practice
1. Ask the right clinical question:
Formulate a searchable question
2. Collect the most relevant publications:
Efficient Literature Searching
Select the appropriate & relevant studies
3. Critically appraise and synthesize the evidence.
4. Integrate best evidence with personal clinical expertise, patient
preferences and values:
Applying the result to your clinical practice and patient.
5. Evaluate the practice decision or change:
Evaluating the outcomes of the applied evidence in your
practice or patient.
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Asking the Right Questions
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Clinical Process and knowledge
requirements
Research evidence sought from
literature searches
Etiology
knowledge about causation
Etiognostic Research
Patient presentation
knowledge about diagnosis
Testing
•History
•Examination
•Investigations
Diagnostic Research
Diagnosis
knowledge about prognosis
Therapy
•Changes prognosis
knowledge about therapeutic effectiveness
Clinical outcome
Prognostic Research
Therapy Research
The Question - Why is it so
Important?
•A good answerable question will help us focus
on evidence that is relevant to a patient’s clinical
needs, (or your own knowledge needs).
•They can suggest high yield search strategies
•They can suggest the forms that useful answers
might take (i.e. what is best research design to
answer our question)
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Formulating Clinical
Questions
• There is no right or wrong way to turn a
scenario/knowledge need into a question.
• Just make sure it is concise, clinical and uses
appropriate language (avoid colloquialism, in
favour of technical language).
• Ask one question at a time.
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PICO(D)
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Population
Intervention
Comparison
Outcome
(Design)
Select best evidence
• Question
– Relevant
– Focussed
• Appropriate Study Type
• Up to Date
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Research Study Design
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Research Design
• Diagnostic tests
Cross sectional study
• Prognosis
Cohort study
• Therapy
RCT
• Patients’
Preferences
Qualitative research
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BMJ 1997;315:1636
What resources could be
searched?
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Why Should We Be Critical
in Our Reading of the
Literature?
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Quality of the Medical
Literature
Journal
N Eng J Med
Ann Intern Med
JAMA
BMJ
Lancet
High Quality Articles
17%
13%
12%
9%
8%
What do we mean by
Research Quality?
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Quality of a Study
The confidence that the study design,
conduct and analysis has minimized
biases in addressing the research
question
The better the quality, the higher is the
likelihood that the results produced in
the study are credible
Quality of a Study
Validity
– The degree to which the results of an observation are correct
for the patients being studied.
Bias
– A process that tends to produce results that depart
systematically from the true values existing in the study
population.
Fletcher et al, 1988; Murphy, 1976
Bias
• Conscious
• Unconscious
• Conflict of Interest
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The Hawthorne Effect
What is it?
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Hawthorne Effect
• Outcomes changed
• By virtue of doing the study
• Irrespective of the intervention
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Hierachy of Evidence
 Experimental studies
– Randomized controlled trials
 Controlled Observational studies
– Case-control studies
 Uncontrolled Observational studies
– Case series
– Case reports
Sacks et al. Am J Med 1982;72:233-240;
Cook et al. Chest 1992;102:305s-311s;
Guyatt et al. JAMA 1993;270:2598-2601
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EBM Basic Skills
• Formulate structured clinical question
• PICO(D)
• Search for evidence
• Systematic
• Select best evidence
• Critically appraise
• GATE Frame
• RAMMbo
• CASP
• CAT maker
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AT-A-GLANCE
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Acronym
Title
Aim
Groups
Limbs – Intervention v Comparator
Absolute Risk Reduction
Number Needed to Treat (NNT)
Clinical Conclusion
Education for patients/carers
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AT-A-GLANCE
Acronym: is there a study name? as a mnemonic
Title: Full title, authors, institute, journal, full reference
Aim: specific aim of the study and why, what outcomes were used?
Groups: who were the research subjects, inclusion criteria, exclusion
criteria, who excluded by chance or bias
Limbs – Intervention v Comparator, ? Versus placebo, ? Blinded, how
randomised,
Absolute Risk Reduction: What the main results?, what the main
results on the outcomes studied, other main results, ? Side-effects, other
harm events
Number Needed to Treat (NNT): How many people do you need to treat
to have one beneficial effect? Eg how many people to save a life? How
many treated to have side-effects?
Clinical Conclusion: What are the main clinical conclusions for you and
the team? Can the results be implemented locally? ? Change in guideline
needed? ? Clinical audit needed?
Education for patients/carers: How can you explain the results to a
patient/guardian prior to consent and explanation? State what you will
actually say eg “Research has shown that………what do you think?”
Guidelines
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Levels of evidence
Level
Type of evidence
I
Evidence obtained from at least one randomised controlled
trial or from meta-analysis of randomised controlled trials
II
Evidence obtained from at least one well-designed controlled
study without randomisation
III
Evidence obtained from well-designed non-experimental
descriptive studies, such as comparative studies, correlation
studies and case control studies
IV
Evidence obtained from expert committee reports or
opinions and/or clinical experience of respected authorities
Grading of
recommendations
Grade
Recommendation
A
(Evidence level I)
Requires at least one randomised controlled trial as part of the body of literature of
overall good quality and consistency addressing the specific recommendation
B
(Evidence levels II, III)
Requires availability of well-conducted clinical studies but not randomised clinical
trials on the topic of recommendation
C
(Evidence level IV)
Requires evidence from expert committee reports or opinions and/or clinical
experience of respected authorities. Indicates absence of directly applicable studies of
good quality
To Summarise
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Summary
Clinical problem
Expertise,
Experience &
Pathophysiology
Summary
Clinical problem
Develop answerable
questions
ETATMBA Module 5
Expertise,
Experience &
Pathophysiology
Summary
Clinical problem
Develop answerable
questions
Search and obtain
relevant articles
ETATMBA Module 5
Expertise,
Experience &
Pathophysiology
Summary
Clinical problem
Develop answerable
questions
Search and obtain
relevant articles
ETATMBA Module 5
Expertise,
Experience &
Pathophysiology
Critical appraisal of
evidence
Summary
Clinical problem
Develop answerable
questions
Search and obtain
relevant articles
ETATMBA Module 5
Expertise,
Experience &
Pathophysiology
Decision making
about diagnosis &
treatment
Critical appraisal of
evidence
Summary
Clinical problem
Develop answerable
questions
Search and obtain
relevant articles
ETATMBA Module 5
Expertise,
Experience &
Pathophysiology
Decision making
about diagnosis &
treatment
Critical appraisal of
evidence
Performance
• Competence
– Knowledge
– Skills
• Proficiency
– Application
– PRACTICE
– Confidence
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Are We Together ???
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