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Evidence-based Practice (EBP)
The What, the Why and the How
J. Irlam, Prof J. Volmink
Primary Health Care Directorate
UCT Faculty of Health Sciences
April 2005
Adapted from a presentation by the South African Cochrane Centre, MRC
Intro to EBP 2005
Outline of lecture Definition of EBP Four Lessons from History Challenges of the Information Age How can EBP help? Concluding comments
Intro to EBP 2005
Evidence-based Practice is..
“..the conscientious, explicit and judicious use of the current best evidence in making health care decisions”
Sackett DL, Richardson WS, Rosenberg W, Haynes RB. Evidence-based Medicine. 1997
Intro to EBP 2005
Why do we need to learn this stuff?
To be able to identify, appraise and apply best evidence in making health care decisions
To be able to continually appraise and assimilate new scientific evidence so as to remain up-to-date with new developments in medical knowledge and practice(UCT MBChB Graduate profile: Core Competencies)
Intro to EBP 2005
The need for EBP“Perhaps the most important issue facing the health care service is not how it should be organised or financed, but whether the care it provides actually works.”
Bandolier, 1997
Intro to EBP 2005
Four Lessons
from History..
Intro to EBP 2005
Lesson 1
Distinguish between medical
ritual and evidence-based
practice
e.g. Optimal number of antenatal visits
Intro to EBP 2005
Lesson 2
What’s good in theory MUST be
tested by sound research
e.g. DES hormone to prevent complications of pregnancy
Intro to EBP 2005
Lesson 3
Clinical experience is necessary
but not sufficient for making good
clinical decisions
e.g. anti-arrhythmic drugs after heart attack
Intro to EBP 2005
Lesson 4
Focus on outcomes that are
important to patients rather than
on surrogate endpoints
e.g. anti-arrhythmic drugs after heart attack
Intro to EBP 2005
Challenges of the Information
Age..
Intro to EBP 2005
The Information Explosion Journals
– over 30 000 biomedical journals
– over 2 million articles per year
Textbooks
Grey literature
MEDLINE: over 14 million citations (Dec. 03)
Worldwide Web
Intro to EBP 2005
Intro to EBP 2005
Recent health news “Too much sleep makes you
fat, say scientists”
“Some flab is fab, says new obesity study”
“Daycare may ward off leukaemia”
Intro to EBP 2005
Who do you believe?
Intro to EBP 2005
How can Evidence-Based Practice
help?
Intro to EBP 2005
Steps towards Evidence-Based Practice
The Five A’s
1. Ask the right question
2. Access the relevant evidence
3. Appraise the evidence– valid? clinically important?
4. Apply the evidence to patient care– feasible? acceptable?
5. Assess clinical practice regularly
Intro to EBP 2005
1. Ask the right question
DEFINE:
Population
Intervention/ Exposure
Comparison group
Outcomes
Intro to EBP 2005
Case scenario 1: to immunise or not to immunise?
John is an infant. His parents seek your advice about the risk of severe adverse reactions to the pertussis vaccine.
Intro to EBP 2005
Case scenario 1What is the clinical question?
POPULATION: Infants
INTERVENTION: Pertussis vaccine
COMPARISON: Non-pertussis/ placebo vaccine
OUTCOME: Severe adverse reactions
Does the pertussis vaccine increase the risk of severe adverse reactions in infants compared to no or other vaccines?
Intro to EBP 2005
Case scenario 2Vasectomy and testicular cancer
George has come to discuss the possibility of getting a vasectomy. He says he has heard something about vasectomy causing an increase in testicular cancer later in life.
You know that the risk of this is low but want to give him a more precise answer.
Intro to EBP 2005
Case scenario 2What is the clinical question?
Population = adult males
Intervention = vasectomy
Comparison = no vasectomy
Outcome = testicular cancer
Does vasectomy increase the risk of testicular cancer in adult males compared to no vasectomy?
Intro to EBP 2005
2. Access the evidence Cochrane Library
– Database of Systematic Reviews (CDSR)– Database of Abstracts of Reviews of Effects
(DARE)– Central Register of Controlled Trials
(CENTRAL)
MEDLINE (PubMed Clinical Queries)– Systematic Reviews– Clinical Queries using Research Methodology Filters
Intro to EBP 2005
Intro to EBP 2005
3. Appraise the evidence - 1
Systematic reviews Randomised controlled trials (RCT) Observational studies (cohort, case-
control, cross-sectional) “Expert” opinions, based on clinical
evidence, descriptive studies, or reports of expert committees
Anecdote: ”Someone once told me…”
BestBest
WorstWorst
Intro to EBP 2005
3. Appraise the evidence - 2
Is the study design appropriate to the question?
What are the risk factors for this condition? Cohort Study or Case-Control Study
Is the diagnostic / screening test valid? Cross sectional (validation) studies
What is the best intervention? Randomised controlled trials (RCTs)
What is the prognosis ? Cohort Study or Case-Control Study
Intro to EBP 2005
3. Appraise the evidence - 3
I. Are the results of the study valid?
Could the results be due to bias?
Could the results be due to confounding?
Could the results be due to chance?
Intro to EBP 2005
Critical appraisal and causal inference
Could it be due to selection or measurement bias?
Could it be due to confounding?
Could it be the result of chance?
Could it be causal?
Apply guidelines and make judgment
NO
NO
NONO
Observed association
Intro to EBP 2005
3. Appraise the evidence - 4
II. What are the results?
Are they large enough ..(As measured by the relative risk, absolute risk, or odds ratio)
and precise enough ..(As measured by the confidence interval or p-
value)
and clinically relevant?(As measured by the Number Needed to Treat
(NNT)
Intro to EBP 2005
Which screening programme would you fund?
Programme A reduced the risk of breast cancer deaths by 34%
Programme B produced an absolute reduction in breast cancer deaths of 0.06%
Programme C meant that 1592 women needed to be screened to prevent 1 death from breast cancer
Programme D increased the proportion of patients surviving breast cancer from 99.82% to 99.88%
Intro to EBP 2005
4. Apply the evidenceIII. How relevant are the results to my patient?
Were the study participants sufficiently different from my patient that the results don’t apply?
Is the treatment feasible in my setting?
What are the potential benefits and harms to my patient from the intervention?
Are my patient’s values and preferences satisfied by the intervention and its consequences?
Intro to EBP 2005
5. Assess your clinical practice regularly
• How good am I in asking answerable clinical questions?
• How successful am I in getting answers to these questions?
• Do I critically appraise the evidence?• How well am I applying the evidence in
my practice?
Intro to EBP 2005
In Conclusion..
Intro to EBP 2005
EBP is a systematic approach to using evidence for better patient care
1. Asking the right questions
2. Accessing the relevant evidence
3. Appraising the evidence– valid? clinically important?
4. Applying evidence to patient care– feasible? acceptable?
5. Assessing clinical practice regularly
Intro to EBP 2005
EBP is about integrating evidence with clinical expertise
“The practice of evidence based medicine means integrating individual clinical expertise with the best available external clinical evidence from systematic research.”
BMJ 1996;312:71-72
Intro to EBP 2005
The potential of EBP Improves continuity and uniformity of care
Provides a structure for effective teamwork
Provides a common structure for problem-
solving and communication
Promotes better use of resources
Rosenberg, Donald. BMJ 1995; 310:17-25
Intro to EBP 2005
The difficulties of EBP
“The notion that right-minded people will naturally make decisions on the basis of the best available scientific evidence is a misleading and dangerous idea”
Erve Chambers, 1985
“The presumption is made that the practice of medicine was previously based on a direct communication with God or by tossing a coin.”
Fowler, Lancet 1995;346:823
Intro to EBP 2005
For the best quality
health care, use of the
best available
evidence is
essential
