1. EBM
Dr Adrian Burger
20 March 2007

2. EBM Intro Evidence based guidelines Evidence based care paths
Evidence based Questions
Evidence based Solutions
Evidence based ……

3. Shift_Expectations Whether to implement How to - sensibly
- efficiently
- avoid misconceptions
EBM CONCEPTS ARE NOW UNAVOIDABLE

4. (Mis)Concepts EBM DOES NOT = RCT
Cannot rely solely on research from RCT
- <14% are RCT
- Observational studies overlooked
- undervalued patient preferences, clinical
circumstances, expertise

5. What You Need to Do Clearly define your question
Thorough literature search
Critically appraise the quality of the evidence
Critically assess the applicability
Balanced application

6. The evidence cycle

7. Balanced application of the evidence

8. Clinical circumstances
Clinical expertise and judgment
Assumes physician competence on basis of
- clinical experience
- development of clinical instincts

9. Patient preferences Individualizes needs Takes into account patients’
- experiences
- values
- expectations

10. Research evidence Ask the question Acquire the information
Appraise the quality
Apply the results
Act on the patient

11. EBM Resources Own research, reviews - Guide to the Medical Literature
Online
- Cochrane Database
- Best Bets

12. Levels of Evidence Hierarchy of evidence RCT
Controlled observational studies
Uncontrolled studies and opinion

13. Studies: First Question
Is the study
- investigating results of a treatment?
Therapeutic Study
- outcome of a disease?
Prognostic Study
- Diagnostic test?
- Developing an economic model/decision
analysis?

14. Studies: Categorize the study
Level 1
RCT or systematic review of RCTs
Level 2
Prospective cohort, poor quality RCT, systematic review
Level 3
Case control, retrospective cohort, systematic review of level 3 studies

15. Categorize the studies 2
Level 4
Case series
Level 5
Expert opinion

16. Level One and Two

17. Level 3-5

18. Errors in Hypothesis Testing
Small sample studies
- Type 2 Beta errors
Probability of concluding that no difference exists when there is a difference
Acceptable rate is 20%
This equals a power of 80%
If >20% then unacceptably high risk of false negatives

19. Errors 2 Type 1 or Alpha Error
Concluding the results of a study are true when in fact it is due to chance or random sampling error
Is an erroneous false positive
Acceptable rate of 5%

20. Power of a study
Probability of concluding a difference between two treatments when one actually does exist
Power = 1- Beta
Can be used before a study to determine study sample size
Can be used after a study to determine if negative findings true or just due to chance

21. Article Injury, 37, 302 – 306 Evidence-based Medicine: What it is
and what it is not