Principles

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Principles Practice ofEvidence-based Medicine
Center for Evidence-Based Medicine Presents the
1st Mini-lectures series

• Roberto Cardarelli, DO, MPH

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Outline

• Defining Evidence-based medicine (EBM)
• Background of EBM
• Practicing EBM
• Limitations of EBM
• How to ask answerable clinical questions

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What is EBM?

• EBM is the integration of
• Best research evidence
• Clinically relevant
• Patient oriented
• Such as dx tests, prognostic markers, therapy
• Clinical expertise
• Use of clinical skills and past experiences to
  identify a patients unique health states and
  needs
• Patient values
• Unique preferences, concerns, expectations each
  patient brings

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Why EBM?

• Clinical Epidemiology.
• Current era was established and renamed EBM in
  1992 by a group led by Gordon Guyatt at McMaster
  University in Canada.
• The spread of EBM arose from 4 realizations
• Our daily need for valid information about dx,
  prognosis, tx, and prevention
• Inadequacy of traditional sources (texts)
• Disparity between diagnostic skills and clinical
  judgment vs. up-to-date knowledge and clinical
  performance
• Inability to afford more than a few second per pt
  for finding and assimilating the evidence

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Why EBM?

• Development of these strategies have made
  practicing EBM possible
• Strategies for efficiently tracking down and
  appraising evidence
• Creation of systematic reviews and concise
  summaries (i.e. Cochrane Collaboration)
• Evidence based journals of secondary publications
• IDing and applying strategies for lifelong
  learning and for improving our clinical
  performance

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Why EBM?

• Keeping up
• knowledge explosion
• medical literature
• Life-long, self-directed learning
• Enhancing clinical practice, resulting in better
  patient outcomes.
• Teaching students/residents based on valid
  evidence.
• What sources do you use?

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Practicing EBM

• Clinically important evidence - POEMS
• therapy
• diagnostic tests
• harm
• prognosis
• cost-effectiveness
• DOES
• molecular biology
• pathophysiology

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Practicing EBM

• Framework of EBM
• Are the results of the study valid?
• What are the results?
• Will the results help with caring for my
  patients?

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Practicing EBM

• Step 1 Create an answerable question
• Step 2 Track down the best evidence to answer
  your question
• Step 3 Critically appraise that evidence for its
  validity (closeness to the truth), impact (size
  of effect), applicability (useful to your pt)
• Step 4 Integrate the critical appraisal with our
  clinical expertise and with our pts unique
  biology, values, and circumstances
• Step 5 Evaluate our effectiveness and efficiency
  in steps 1-4 and seek ways to improve them for
  the next time

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Types of Clinical Questions

• Therapy -- Is this treatment any good?
• Diagnostic test -- How good is this test?
• Harm -- Does this exposure cause harm?
• Prognosis -- What is the likely clinical course?
• Economic Analysis -- Is this intervention
  cost-effective?
• Clinical Guideline -- What should I do for this
  problem?
• Overview -- Is there scientific evidence to guide
  our decisions?

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Information to look for

• Some conditions and their treatments change
  frequently-
• What do you do?
• YOU find the best current evidence that gives
  up-to-date protocols that are crucial to medical
  management.
• Conditions that are encountered less often.
• What do you do?
• You should try to find a review (EBM) that
  another person may have done. Just make sure
  that you can apply the evidence to your patient.

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Limitations to EBM

• Shortage of coherent scientific evidence
• Difficulties of applying evidence to an
  individual pt
• Developing new skills to practice EBM (searching
  EBM, statistics, etc)
• Limited time of the busy practitioner
• Evidence that EBM works is limited.

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Step 1 Asking a clinical question

• Background questions have 2 components
• Question root
• Aspect of the disorder
• Ex What causes cyanosis?
• Foreground questions w/ 4 components
• Pt or problem of interest
• The main intervention (dx, tx, prognostic fxs)
• Comparison intervention(s), if relevant
• Clinical outcome(s) of interest

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Step 1 Asking a clinical question

• When our experience of a specific condition is
  limited- we tend to ask more background questions
• As our experience grows- we should and tend to
  ask more foreground questions
• EX In patients with suspected pneumonia, are any
  clinical findings sufficiently powerful to
  confirm or exclude pneumonia all by themselves,
  or is a CXR necessary for the dx?

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Figure 1.
Foreground
Background
Experience with Condition
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Rx
Educational Prescription
Pt Name Date
Target Disorder
Intervention (/- comparison)
Outcome
Discuss Search strategy Search
results Validity Importance of the valid
results Can you apply this to your pt
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Rx
Educational Prescription
Pt Name John Doe Date 8/18/03
Target Disorder Pneumonia
Intervention (/- comparison) Power of clinical
exam vs clinical exam CXR
Outcome Confirm or exclude pneumonia
Discuss Search strategy Search
results Validity Importance of the valid
results Can you apply this to your pt
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Curriculum for next 6 lectures

• Overview of basic statistics
• Diagnosis and screening
• Prognosis
• Therapy
• Harm
• Applying EBM to your patient