1. What Really is Evidence Based Medicine?
Dr. Nick Price
Training Programme Director (Bradford)

2. Objectives
To have an overall understanding of the concept of evidence based practice.
To critique how ‘evidence’ is presented in journals and by journalists.
Raise awareness of other factors that influence clinical decision making.
To be able to apply simple statistics in practice.
To be able to present these to patients, minimising bias.
To develop some of the skills in this area required to pass the MRCGP.

3. Schedule 1400-1500 Overview of EBP Panorama programme on Herceptin.
Tea
Group work
Critically appraising an editorial.
Working out some numbers
Practice explaining risk to patients
Summary and evaluation (plenary)

4. What is evidence based practice?

5. Evidence based medicine?
Maybe it is the application of the best available scientific knowledge to the patient’s or population’s clinical problem? Or
‘Evidence-based medicine is the integration of best research evidence with clinical expertise and patient values’ Sackett et al (2000)

7. A model of influences in clinical decision making
Science Social Science
Scientific Method
Counting differences
Understanding differences
Technical judgement
Arts and humanities
Ethics
Adaptability, broad perspective
Humane Judgement
Clinical Judgement

8. Principles of a health care system
Systematic review
Meta-analysis
equity
effectiveness
efficiency
appropriateness
accessibility
responsibility
humanity
RCT
Cohort studies
Case control studies
Descriptive studies
quantitative
qualitative

10. Panorama

11. ‘Should I sell my house to pay for Herceptin, Doctor
‘Should I sell my house to pay for Herceptin, Doctor?’ How would you gather evidence?

12. First define your question PICO
Population
Intervention(s)
Comparison
Outcome.

13. Levels of evidence
(I-1) a well done systematic review of 2 or more RCTs
(I-2) a RCT
(II-1) a cohort study
(II-2) a case-control study
(II-3) a dramatic uncontrolled experiment
(III) respected authorities, expert committees, etc..
(Good Old Boys Sitting Heroically At Tables?)
(IV)....someone once told me...

14. Gathering evidence Thorough Practical Medline search
SR and Meta-analyses
RCTs
Review articles
Observational Studies
Clinical Evidence
Cochrane
Bandolier
DTB MeReC
RCGP/RCPsych guidelines
NICE guidelines
NSF
Local Guidelines
Ask the consultant or others?

15. What I actually did for Herceptin
Medline – got nowhere really
– got nowhere really
Asked my mates a bit.
– editorial and then references from that.
Could have done what?

16. Making sense of numbers
Relative risk
Absolute risk
Absolute risk reduction / harm
NNT
NNH
Hazard Ratio
Cost per case / QALY

17. So lies damn lies and statistics?
Absolute risk / benefits often sound small
Relative risk / benefits can sound big
e.g.
Your chance of winning the lottery with 2 tickets as opposed to one is increased by 1 in 14million
Your chance of winning the lottery with 2 tickets as opposed to one is increased by 100%

18. Numbers Needed to Treat
The average number of people from a defined population you would need to treat with a specific intervention for a given period of time to achieve one beneficial outcome.
NNT = 1 / ARR
Can you calculate this for winning the lottery jackpot?
Assume chance of winning is 1 in 14m per ticket per draw.

19. NNTs 2 ARI = 1/14m per ticket per draw
= 1/14m x 2 per week with 1 ticket for each
draw
= 1/14m x2 x52 x5 for 5 years
= 520/14m
NNT = 14m/520 = 27,000 approx
i.e. 27,000 people have to buy 2 tickets a week for 5 years for one person to win the jackpot

20. Summary Trials are there to inform clinical decision making.
Identifying appropriate literature needs to consider quality / rigour but also practicality.
Some stats are really quite easy but need to be used with care if you are to be honest.
I suggest that risks and benefits should be expressed in both absolute terms and relative terms and DON’T mix them up!

21. Some reading / resources:
Greenhalgh T (2000) How to Read a Paper: The basics of evidence based medicine. London BMJ Publishing
McGovern D P B, Summerskill W S M, McManus R (2001) Evidence-based medicine in General Practice. Oxford BIOS Scientific. OR
Sackett DL, Strauss S, Richardson WS, Rosenberg W, Hayes RB (2000) Evidence-based Medicine: How to practice and Teach EBM. Edinburgh Churchill Livinstone

22. Tea time Then: Reviewing the editorial and doing some sums.
Back here for 1615 for close and evaluation