2. Evidence Base Medicine
A.A. Karimi MD.

3. EBM
Sciences
Clinic

4. “A 21st century clinician who cannot critically read a study is as unprepared as one who cannot take a blood pressure or examine the cardiovascular system.”
BMJ 2008:337:

5. Dr. Sackett defines EBM as:
A BRIEF HISTORY
1990: McMasters University in Ontario, Canada
Dr. David Sackett and colleagues proposed Evidence Based Medicine (EBM) as a new way of teaching, learning and practicing medicine.
Dr. Sackett defines EBM as:
“…The conscientious, explicit, and judicious use of current best evidence in making decisions about the care of individual patients.”

6. What is Evidence-Based Medicine?
“Evidence-based medicine is the integration of best research evidence with clinical expertise and patient values

7. Evidence Based Medicine
Patient
Values
Medical Decision
Clinical
Expertise
Research
Evidence

8. Values, Concerns Preferences, Expectations
PATIENT
Values, Concerns Preferences, Expectations
Life predicament
EBM
INFORMATION
Clinically relevant
Proven by research
Best up-to-date evidence
PHYSICIAN
Training & Experience
Current Expertise
Continued learning
Demand for proof

9. THE FIVE BASIC STEPS OF EBM
1.Clinical Question Patient-focused, problem-oriented 2. Find Best Evidence Literary Search 3. Critical Appraisal Evaluate evidence for quality and usefulness 4. Apply the Evidence Implement useful findings in clinical practice 5. Evaluate The information, intervention, and EBM process

10. The MOST IMPORTANT step!
The Clinical Question
PICO
????????
The FIRST step
The HARDEST step
The MOST IMPORTANT step!
RCT

11. Formulate your clinical question:
Patient or Population
Be specific
Intervention
Comparison Group
i.e. standard therapy, “gold standard”
Outcome of Interest
i.e. efficacy of therapy, mortality, specificity of diagnostic test

12. EBM QUESTION: Should include multiple factors
(Examples)
P PATIENT type of patient or population
Ex: 47 yr male w/DM2 and cellulitis toe, 25 yr female w/DVT and chest pain
I INTERVENTION clinical intervention
Ex: medication, procedure, test, surgery, radiation, drug, vaccine
C COMPARISON compare alternative treatment
Ex: other prior, new or existing therapy
O OUTCOME clinical outcome of interest
Ex: Reduced death rate in 5 yrs, decreased infections, fewer hospitalizations

13. In the following questions, identify the missing component:
Is oral rehydration in the emergency room more cost-effective than IV rehydration?
Patient/Population
Not identified. Examples: infants, infants with vomiting.
Intervention
Oral rehydration.
Comparison
IV rehydration.
Outcome
Cost-effectiveness.

14. Will atrovent help prevent hospitalization of my 2 year old patient with an acute asthma exacerbation?
Patient/Population
Child w/ acute asthma
Intervention
Atrovent
Comparison
Not identified. Examples: standard therapy, albuterol alone.
Outcome
Prevent hospitalization.

15. Classify the Clinical Question into Domain
Therapy
Randomized controlled trials or meta analyses
Diagnosis
Sensitivity and specificity, predictive value, diagnostic errors
Prognosis
Cohort studies, survival analysis
Harm or Casualty
Case control studies, cohort studies

17. Research Study Design

18. Research Design Diagnostic tests Cross sectional study Prognosis
Therapy
Patients’ Preferences
Cross sectional study
Cohort study
RCT
Qualitative research
Research design
BMJ 1997;315:1636

19. What resources could be searched?

20. Why Should We Be Critical in Our Reading of the Literature?

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

22. What do we mean by Research Quality?

23. 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
Self explanatory

24. Quality of a Study Validity Bias
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
Important concepts when appraising papers.

25. Bias
Conscious
Unconscious
Conflict of Interest

26. The Hawthorne Effect
What is it?

27. Hawthorne Effect Outcomes changed By virtue of doing the study
Irrespective of the intervention

28. 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: ;
Cook et al. Chest 1992;102:305s-311s;
Guyatt et al. JAMA 1993;270:
Levels of quality.
Why?
BIAS - greater as we come down the hierachy.

29. EBM Basic Skills Critically appraise GATE Frame RAMMbo CASP CAT maker
Formulate structured clinical question
PICO(D)
Search for evidence
Systematic
Select best evidence
Critically appraise
GATE Frame
RAMMbo
CASP
CAT maker
The tools under 'Critically appraise" are hyperlinked so that they can be demonstrated, if necessary - not essential. 29

30. 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

31. 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?”

32. Guidelines

33. 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
This will be seen in guidelines.
Remember- we still have to be critical about the primary studies - even RCTs and Systematic Reviews can be flawed!

34. 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
Again - will be seen in guidelines.

35. To Summarise

36. Experience & Pathophysiology
Summary
Expertise,
Experience & Pathophysiology
Clinical problem
This is a schematic exposition of the process.

37. Experience & Pathophysiology
Summary
Expertise,
Experience & Pathophysiology
Clinical problem
Develop answerable questions
This is a schematic exposition of the process.

38. Experience & Pathophysiology
Summary
Expertise,
Experience & Pathophysiology
Clinical problem
Develop answerable questions
Search and obtain relevant articles
This is a schematic exposition of the process.

39. Experience & Pathophysiology
Summary
Expertise,
Experience & Pathophysiology
Clinical problem
Develop answerable questions
Search and obtain relevant articles
This is a schematic exposition of the process.
Critical appraisal of evidence

40. Experience & Pathophysiology
Summary
Expertise,
Experience & Pathophysiology
Clinical problem
Develop answerable questions
Decision making about diagnosis & treatment
Search and obtain relevant articles
This is a schematic exposition of the process.
Critical appraisal of evidence

41. Experience & Pathophysiology
Summary
Expertise,
Experience & Pathophysiology
Clinical problem
Develop answerable questions
Decision making about diagnosis & treatment
Search and obtain relevant articles
This is a schematic exposition of the process.
Critical appraisal of evidence

42. Thank You