This document provides an overview of evidence-based practice and the steps involved. It discusses: 1) What evidence-based medicine is and its key principles of integrating the best research evidence with clinical expertise and patient values. 2) The four steps of evidence-based practice: formulating a clinical question, searching for evidence, appraising the research, and applying to individual patients. 3) Tools for critically appraising different types of research studies, such as randomized trials and systematic reviews, to assess their validity and potential for bias.

1. Why bother with
Evidence-Based Practice?
Professor Paul Glasziou
Bond University
www.crebp.net.au/
www.testingtreatments.org
Free pdf: Ch 5, 6, 7

2. Introductory Lecture: Objectives
What is Evidence-Based Medicine?
The steps of doing EBM
1. Formulate Clinical Questions
2. Search for Evidence
3. Appraisal of research
4. Apply to clinical problem

3. What is Evidence-Based Medicine?
“Evidence-based medicine is the integration of best
research evidence with clinical expertise and
patient values”
- Dave Sackett
Patient Concerns
Clinical Expertise
Best ResearchSackett DL, Rosenberg WMC, Gray JAM, Haynes RB, Richardson WS: Evidence based medicine:
what it is and what it isn’t. BMJ 1996;312:71-2.

4. “EBM” - birth of a term
Update of CMAJ series on how
to read a paper
JAMA User guides 1991
authors seek a new term
Clinical epidemiology?
Scientific medicine?
Evidence-based medicine!

5. The need for Evidence
Vertebroplasty for osteoporotic fractures
Gray et al Spine 2008. Nation-wide and State-specific primary
vertebroplasty rates per 100,000 Part B fee-for-service
Steady rise in use of vertebroplasty
for a decade
2009: two large trials publish
showing no effect over placebo
Slides courtesy R Buchbinder

6. Unnecessary Procedures
http://www.cbsnews.com/8301-18563_162-5217954.html
Please click on the black screen to view the video

7. that did not work
 Vertebroplasty for osteoporotic fractures (NEJM,
2010)
 Arthoscopic knee lavage (Moseley, NEJM, 2002)
 Blood glucose monitoring for non-insulin
dependent diabetes (DiGEM trial, BMJ 2007)
 Tight control of diabetes (ACCORD, NEJM, 2010)
 Prostate cancer screening (Djulbegovic, BMJ
2010)
 Ovarian cancer screening (JAMA, 2011)

8. Most medical innovations don’t work
an analysis of 136 trials in myeloma
New Treatment
Better
New Treatment
Worse

9. How can we find the research that will improve
the care of our patients?
0
500000
1000000
1500000
2000000
2500000
Biomedical MEDLINE Trials Diagnostic?
MedicalArticlesperYear
5,000?
per day
1,500
per day
95 per
day
MedicalArticlesPerYear
19 of 20

10. What should you believe?

11. Keeping up to date
What is your JASPA* score?
* (Journal Associated Score of Personal Angst)
J: Are you ambivalent about renewing your JOURNAL
subscriptions?
A: Do you feel ANGER towards prolific authors?
S: Do you ever use journals to help you SLEEP?
P: Are you surrounded by PILES of PERIODICALS?
A: Do you feel ANXIOUS when journals arrive?
*Modified from: BMJ 1995;311:1666-1668
0 (?liar)
1-3 (normal range)
>3 (sick; at risk for polythenia gravis and
related conditions)

12. Coping with the overload:
three possible things you might try
A. Read an evidence-based
abstraction journal
(and cancel other journals)
B. Keep a logbook of your
own clinical questions
C. Run a case-discussion journal
club with your practice

13. Part 2: The 4 steps of “pull” EBM
1. Formulate an answerable question
2. Track down the best evidence
3. Critically appraise the evidence
4. Individualise, based clinical expertise and patient concerns

14. Step 1
Formulate an answerable clinical question
Structure of researchable
questions – PICO-T
 Population/Patients
 Intervention
 Comparison
 Outcome
 Time

15. Formulating answerable clinical
questions
Structure of researchable
questions – PICO-T
 Population/Patients
 Outcome

16. What are your clinical questions?
 A 35 year old man says his brother
recently died of a ruptured
cerebral aneurysm.
He is worried about whether he
might have one and what the
chances are that it would rupture.
-> PICO Table

17. Risk Factors
Cause(s)
Symptoms
Signs, Tests
Prognosis
Treatment Effect
Past Current Future
Types of question: stroke
Frequency
Cohort Study SurveyInception Cohort Study
Treatments
Randomised Trial
CT Scan
Cross Sectional Study

18. What are the … outcomes (PO?)
Outcomes ?
Patients
Qualitative Research

19. The “best” evidence depends
on the type of question
Level Treatment Prognosis Diagnosis
I
II Randomised
trial
Inception
Cohort
Cross
sectional
III

20. Level Treatment Prognosis Diagnosis
I Systematic
Review of …
Systematic
Review of …
Systematic
Review of …
II Randomised
trial
Inception
Cohort
Cross
sectional
III
The “best” evidence depends
on the type of question

21. What do you do about conflicting
claims?

22. 2. Searching: finding good answers?

23. Impact of searching on correctness
of answers to clinical questions
Right to
Right
Wrong to
Right
Right to
Wrong
Wrong to
Wrong
McKibbon
(GP or IM)
28% 13% 11% 48%

24. Impact of searching on correctness
of answers to clinical questions
Right to
Right
Wrong to
Right
Right to
Wrong
Wrong to
Wrong
McKibbon
(GP or IM)
28% 13% 11% 48%
Quick Clinical
(GPs)
21% 32% 7% 40%
Hersh
(Med students)
20% 31% 12% 36%
Hersh
(Nursing)
18% 17% 14% 52%

25. 3. Rapid Critical Appraisal
It’s peer-reviewed, therefore it must be OK?

26. Is the PICO a POEM?
Patient
Oriented
Evidence that
Matters

27. Critical Appraisal Steps
Did you find good quality studies?
Two steps
1.What is the PICO (Question)
2.Is the potential bias low?
• “RAMMbo” (Valid Study?)
• “FAITH” (Valid Review?)

28. Use the RAMMbo to check validity
Was the Study valid?
1. Representativeness
 Who did the subjects represent?
1. Allocation
 Was the assignment to treatments
randomised?
1. Maintainence
 Were the groups treated equally?
1. Measurements blinded OR
objective
 Were patients and clinicians
“blinded” to treatment? OR
 Were measurements objective &
standardised?
Modified from: User Guide. JAMA, 1993

29. Fundamental Equation of Error
 Measure = Truth + Bias + Random Error
Use
good study
design
Use
large numbers
Researcher
Critically
Appraise
Design
Confidence
Intervals
and
P-values
Reader

30. Two methods of assessing the role
of chance
 P-values (Hypothesis Testing)
 use statistical test to examine the ‘null’
hypothesis
 associated with “p values” - if p<0.05 then
result is statistically significant
 Confidence Intervals (Estimation)
 estimates the range of values that is likely to
include the true value
Relationship between p-values and confidence intervals - if the
value corresponding to ‘no effect’ (RR of 1 or treatment difference of
0) falls outside the CI then the result is statistically significant

31. Step 4: Applying to the individual
 What do the results mean on average?
 What do they mean for this individual?

32. Applying research requires both “Whether to” and
“How to”
 “Whether to”
 Evidence quality
 Individual applicability
 “How to”
 What & where?
 How long & how often?
BMJ 2003; 327 : 135