Evidence based medicine

1. ETATMBA Module 5
Evidence-Based Medicine in
Clinical Practice.
Dr. Harry Gee
Dr. Chisale Mhango

2. ETATMBA Module 5
"Every intervention is a two-
edged sword."
Iain Chalmers

3. Old paradigm
Unsystematic
clinical experience
Pathophysiology
Content expertise
& authoritarianism
New paradigm
Systematic clinical
experience
Pathophysiology
necessary but not
sufficient
Rules of evidence
Practice Pradigms

4. ETATMBA Module 5
Pre-Requisites
• Questioning
– The Knowledge Gap
– Honesty
– Humility
– Discerning
• What is merely custom and
practice?
• Desire for Improvement

5. ETATMBA Module 5
Our Aims
• Understand EBM
– What is it?
– Why do we need it?
– What are the benefits?
– Who benefits?

6. ETATMBA Module 5
Our Objectives
The key steps:
– Formulate a clinical question
– Search the literature
• Efficiently
• Confidently
– Appraise the evidence
– Apply the evidence

7. ETATMBA Module 5
What is EBM?

8. ETATMBA Module 5
Good Clinical Practice
• Knowledge from best external evidence
based on clinical research
• Judgement from experience.
• Understanding of patient's beliefs &
preferences.
Sackett 1996

9. ETATMBA Module 5
Who Benefits?

10. ETATMBA Module 5
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

11. ETATMBA Module 5
EBM for the Clinician
• Knowledge & Skills
• Proficiency
– Application
– PRACTICE
– Confidence

12. ETATMBA Module 5
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.

13. ETATMBA Module 5
Asking the Right Questions

14. Patient presentation
knowledge about diagnosis
Testing
•History
•Examination
•Investigations
Diagnosis
knowledge about prognosis
Therapy
•Changes prognosis
knowledge about therapeutic effectiveness
Clinical outcome
Etiology
knowledge about causation
Research evidence sought from
literature searches
Clinical Process and knowledge
requirements
Etiognostic Research
Diagnostic Research
Prognostic Research
Therapy Research

15. ETATMBA Module 5
•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)
The Question - Why is it so
Important?

16. ETATMBA Module 5
• 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.
Formulating Clinical
Questions

17. ETATMBA Module 5
PICO(D)
• Population
• Intervention
• Comparison
• Outcome
• (Design)

18. ETATMBA Module 5
Select best evidence
• Question
– Relevant
– Focussed
• Appropriate Study Type
• Up to Date

19. ETATMBA Module 5
Research Study Design

20. ETATMBA Module 5
Research Design
• Diagnostic tests
• Prognosis
• Therapy
• Patients’
Preferences
Cross sectional study
Cohort study
RCT
Qualitative research
BMJ 1997;315:1636

21. ETATMBA Module 5
What resources could be
searched?

22. ETATMBA Module 5
Why Should We Be Critical
in Our Reading of the
Literature?

23. Journal High Quality Articles
N Eng J Med 17%
Ann Intern Med 13%
JAMA 12%
BMJ 9%
Lancet 8%
Quality of the Medical
Literature

24. ETATMBA Module 5
What do we mean by
Research Quality?

25. 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

26. 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
Quality of a Study

27. ETATMBA Module 5
Bias
• Conscious
• Unconscious
• Conflict of Interest

28. ETATMBA Module 5
The Hawthorne Effect
What is it?

29. ETATMBA Module 5
Hawthorne Effect
• Outcomes changed
• By virtue of doing the study
• Irrespective of the intervention

30. ETATMBA Module 5
 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
Hierachy of Evidence

31. ETATMBA Module 5
EBM Basic Skills
• Formulate structured clinical question
• PICO(D)
• Search for evidence
• Systematic
• Select best evidence
• Critically appraise
•GATE Frame
•RAMMbo
•CASP
•CAT maker

32. ETATMBA Module 5
AT-A-GLANCE
• Acronym
• Title
• Aim
• Groups
• Limbs – Intervention v Comparator
• Absolute Risk Reduction
• Number Needed to Treat (NNT)
• Clinical Conclusion
• Education for patients/carers

33. 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?”

34. ETATMBA Module 5
Guidelines

35. 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

36. 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

37. ETATMBA Module 5
To Summarise

38. Expertise,
Experience &
Pathophysiology
Clinical problem
Summary

39. ETATMBA Module 5
Expertise,
Experience &
Pathophysiology
Clinical problem
Summary
Develop answerable
questions

40. ETATMBA Module 5
Expertise,
Experience &
Pathophysiology
Clinical problem
Summary
Develop answerable
questions
Search and obtain
relevant articles

41. ETATMBA Module 5
Expertise,
Experience &
Pathophysiology
Clinical problem
Summary
Develop answerable
questions
Search and obtain
relevant articles
Critical appraisal of
evidence

42. ETATMBA Module 5
Expertise,
Experience &
Pathophysiology
Clinical problem
Summary
Develop answerable
questions
Search and obtain
relevant articles
Critical appraisal of
evidence
Decision making
about diagnosis &
treatment

43. ETATMBA Module 5
Expertise,
Experience &
Pathophysiology
Clinical problem
Summary
Develop answerable
questions
Search and obtain
relevant articles
Critical appraisal of
evidence
Decision making
about diagnosis &
treatment

44. ETATMBA Module 5
Performance
• Competence
– Knowledge
– Skills
• Proficiency
– Application
– PRACTICE
– Confidence

45. ETATMBA Module 5
Are We Together ???