Evidence-based Practice (EBP) The What, the Why and the How

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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

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Outline of lecture

• Definition of EBP
• Four Lessons from History
• Challenges of the Information Age
• How can EBP help?
• Concluding comments

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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

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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)

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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

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• Four Lessons
• from History..

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Lesson 1

• Distinguish between medical ritual and
  evidence-based practice
• e.g. Optimal number of antenatal visits

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Lesson 2

• Whats good in theory MUST be tested by sound
  research
• e.g. DES hormone to prevent complications of
  pregnancy

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Lesson 3

• Clinical experience is necessary but not
  sufficient for making good clinical decisions
• e.g. anti-arrhythmic drugs after heart attack

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Lesson 4

• Focus on outcomes that are important to patients
  rather than on surrogate endpoints
• e.g. anti-arrhythmic drugs after heart attack

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Challenges of the Information Age..
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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

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Recent health news

• Too much sleep makes you fat, say scientists
• Some flab is fab, says new obesity study
• Daycare may ward off leukaemia

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Who do you believe?
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How can Evidence-Based Practice help?
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Steps towards Evidence-Based PracticeThe Five As

• Ask the right question
• Access the relevant evidence
• Appraise the evidence
• valid? clinically important?
• Apply the evidence to patient care
• feasible? acceptable?
• Assess clinical practice regularly

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1. Ask the right question

• DEFINE
• Population
• Intervention/ Exposure
• Comparison group
• Outcomes

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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.

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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?

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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.
•  

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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?

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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

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3. Appraise the evidence - 1
Best

• 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

Worst
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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

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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?

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Critical appraisal and causal inference
Could it be due to confounding?
Could it be due to selection or measurement bias?
NO
NO
Observed association
Could it be the result of chance?
Apply guidelines and make judgment
Could it be causal?
NO
NO
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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)

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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

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4. Apply the evidence

• III. How relevant are the results to my patient?
• Were the study participants sufficiently
  different from my patient that the results dont
  apply?
• Is the treatment feasible in my setting? 
• What are the potential benefits and harms to my
  patient from the intervention?
• Are my patients values and preferences satisfied
  by the intervention and its consequences?

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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?

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In Conclusion..
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EBP is a systematic approach to using evidence
for better patient care

• Asking the right questions
• Accessing the relevant evidence
• Appraising the evidence
• valid? clinically important?
• Applying evidence to patient care
• feasible? acceptable?
• Assessing clinical practice regularly

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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 199631271-72

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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 31017-25

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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 1995346823

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• For the best quality health care, use of the best
  available evidence is
• essential