Critically Appraising Research A Consumers Perspective Gary S. Gronseth, M.D. Department of Neurolog


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Critically Appraising ResearchA Consumers
PerspectiveGary S. Gronseth M.D.Department
of NeurologyUniversity of KansasOctober 12
2006
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Clinical
Outcomes
Basic
What causes disease and defining approaches to
diagnosis and treatment
What works and what does it cost in real-world
settings
How can disease be prevented or treated under
controlled settings
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Steroids
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• The use of steroids for Bells palsy has become
  the standard of care in the community.

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• The consequences of disfiguring facial weakness
  are so devastating that the use of steroids is
  mandatory.

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• Fallacious
• Irrelevant
• Rhetoric
• Psychological appeal
• Emotion-Driven
• Persuasion

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Common fallacious arguments in medicine

• Popularity
• Begging the question
• Irrelevant Outcomes

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Irrelevant Outcomes
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• Fallacious
• Irrelevant
• Rhetoric
• Psychological appeal
• Emotion-Driven
• Persuasion

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Decison
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Decision
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Decision
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Deductive ArgumentPrinciples

• Steroids
• Reduce inflammation
• Reduce compression within temporal bone

Good for hypothesis generation Often not
Convincing When convincing no controversy
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Decision
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Decision
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Decision
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Decision
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Anecdotal argument

• The last patient I saw with Bells palsy who
  didnt get steroids never got better.

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ExperienceCollections of Anecdotes

• My Experience

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Expert opinion

• From a practical view point treatment with
  steroids is appropriate for the management of
  Bells Palsy.
• Bells Palsy remains without a proven
  efficacious treatment.

Stankiewicz 1987
May 1975
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Limitations of Experience
More likely to remember anecdotes that
are Recent Extreme Support our preconceptions
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EvidenceCollections of Recorded Anecdotes

• My Experience

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Decision
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The results of this study demonstrate no
statistically significant beneficial effect of
steroid therapy upon recovery from Bells
Palsy.P 0.32
May et. al. 1975

• Relative Rate
• Complete Recovery
• 0.92 (0.60 to 1.4)

Insufficiently powered to exclude a benefit
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The control group included mainly those patients
who had refused to take prednisilone because
they were afraid of developing complications and
those with a relative contraindication to
steroids (e.g. moderate hypertension)
Shafshak et al 1994
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The Literature is full of

• Fallacious arguments
• Contradictory expert opinions
• Misinterpretations of errors of chance
• Studies with a high risk of bias

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Find and analyze all of the evidence in a
transparent and systematic fashion
or find someone who already has.
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AAN clinical practice guidelines Above the fray
Franklin Gary M. MD MPH Zahn Catherine A. MD
Neurology Volume 59(7)8 October 2002pp 975-976

• Avoid fallacious arguments
• Involve experts but dont allow their conclusions
  to go beyond the evidence
• Find all relevant studies
• Systematically assess and grade the quality of
  the studies to avoid spin

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Clinical
Outcomes
Basic
What causes disease and defining approaches to
diagnosis and treatment
What works and what does it cost in real-world
settings
How can disease be prevented or treated under
controlled settings
Patient-based
Pre-clinical
Organizational- based
Patient Population-based
Translation 2 Humans to Bedside/Curbside
Translation 1 Bench to Humans
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Practice Guideline

• Systematic and Transparent

Many Specialty Societies
Cochrane collaboration
AAN
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Consensus vs. Evidence

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Consensus-Based Evidence-Based

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Evidence-based Argument

• Question
• Evidence
• Conclusion
• Recommendation

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Do steroids work for Bells palsy
For patients with acute Bells palsy do oral
steroids given within the first week improve
facial functional outcomes
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Do steroids improve facial functional recovery in
patients with for Bells palsy
Patients Acute Bells Palsy Intervention Ora
l Steroids Given within 1 week Outcomes F
acial Function
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Should we do this

• For patients with (suspected) Bells palsy
• Therapeutic does early use of oral steroids
  improve facial outcomes

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Should we do this

• For patients with (suspected) Bells palsy
• Therapeutic does early use of oral steroids
  improve facial outcomes
• Prognostic does facial CMAP testing identify
  patients at increased risk for poor
  outcomes

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Should we do this

• For patients with (suspected) Bells palsy
• Therapeutic does early use of oral steroids
  improve facial outcomes
• Prognostic does facial CMAP testing identify
  patients at increased risk for poor
  outcomes
• Screening does head MRI identify patients
  with treatable etiologies

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The Answer

• Qualitative
• Yes (No Maybe Cant tell) for patients with
  condition A intervention B is effective
  (useful superior) to improve outcome C.
• QuantitativeHow much does the intervention
  improve outcomes
• CertaintyHow confident are we in the answer

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Evidence-based Argument

• Question
• Evidence
• Conclusion
• Recommendation

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Evidence

• Find all relevant studies
• Assess
• Risk of Bias
• Results
• Random Error
• Generalizability

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Find the EvidenceThe Literature
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Literature Search
Apriori inclusion criteria.
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Literature SearchSteroids for Bells Palsy
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Studies of outcomes in Bells Palsy patients some
getting steroids some not getting steroids
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Steroid Studies

• Yr Author
• 94 Shafshak
• 93 Austin
• 87 Abraham
• 82 Brown
• 78 Wolf
• 76 May
• 72 Adour
• 54 Taverner

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How good is the Evidence
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Grading the Evidence
The quality of evidence is always judged as it
pertains to the clinical question.
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AANs Evidence Classification Schemes

• Therapeutic
• Diagnostic/Prognostic Accuracy
• Screening

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AANClassification of evidence

• Class
• I
• II
• III
• IV

Risk of Bias Low Moderately Low Moderately
High High
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Study
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AAN Grading the evidence

• Class
• I
• II
• III
• IV

Controlled

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No Comparison Group
Poor Good
St
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No Comparison Group

• Natural History
• Placebo Response
• Regression to the Mean

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Confounding
Potential known and unknown confounding
differences between treated untreated group
St
-St
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ControlledMatching
Potential unknown confounding differences between
treated untreated group
St
M
-St
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ControlledRandomized Trial
No confounding differences between treated
untreated group
St
R
-St
...unless you are unlucky.
Or
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ControlledConcealed Allocation
Is the study truly randomized
St
R
-St
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Cross OversLost Randomization
St
R
-St
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Cross OversIntent-to-treat
St
R
-St
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Losses to Follow UpLost Randomization
St
R
-St
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Losses to Follow UpIntent to Treat
St
R
-St
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AAN Grading the evidence

• Class
• I
• II
• III
• IV

Controlled randomized matched comparative unc
ontrolled

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AAN Grading the evidence

• Class
• I
• II
• III
• IV

Controlled randomized matched comparative unc
ontrolled
Masking
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Masking
St
-St
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Masking

• Patient
• Treating Providers
• Outcome assessors

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AAN Grading the evidence

• Class
• I
• II
• III
• IV

Controlled randomized matched comparative unc
ontrolled
Masking masked outcome masked
outcome independent non-independent
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Steroid Studies

• Author Random. Comp FU Masked
• May R 100 Y
• Taverner R 100 Y
• Brown R 100 Y
• Austin R 71 Y
• Shafshak NR 100 Y
• Wolf R 100 N
• Adour NR 85 N
• Abraham NR 100 N

• Class
• I
• I
• II
• II
• III
• IV
• IV
• IV

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What does the evidence show

• The studys results
• (Not the authors conclusions)

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Effect of SteroidsRate Difference

Outcome


Treatment

Poor

Good

Steroids

15

85

No Steroids

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67


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Categorical Outcomes are the most clinically
relevant
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Measures of Effect

• Therapeutic questions
• Rate Difference
• Relative Rates
• Odds Ratios
• Diagnostic questions
• Sensitivity/Specificity
• Likelihood Ratios
• Screening questions
• Yields

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Rate Difference Good RecoverySteroids vs No
Steroids
60
I
II
III
IV
40
20
Rate Difference
0
-20
-40
May
Taverner
Brown
Austin
Shafshak
Wolf
Adour
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Evidence-based Argument

• Question
• Evidence
• Conclusion
• Recommendation

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Synthesis
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I
II
III
IV
40
20
Rate Difference
0
-20
-40
May
Taverner
Brown
Austin
Shafshak
Wolf
Adour
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Decrease Random Error (Include all studies)
Decrease Risk of Bias (Exclude studies with a
higher risk of Bias)
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Cumulative Meta-analysis

• Do not Consider Class IV evidence
• Iteratively combine results of studies with the
  least risk of bias until you arrive at a
  sufficiently precise measure of effect or you run
  out of studies
• Grade the strength of the conclusion based on the
  most bias prone study used to determine the effect

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Combine Class I evidence
60
I
40
20
Rate Difference
0
-20
-40
Pooled
May
Taverner
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Hypothetical
60
I
40
20
Rate Difference
0
For patients with Bells palsy steroids are
established to increase the likelihood of good
facial functional recovery by about 12 percent.
-20
-40
Pooled
May
Taverner
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Combine Class I and Class II evidence
60
I
II
40
20
Rate Difference
0
For patients with Bells palsy steroids probably
increase the likelihood of good facial functional
recovery by about 12 percent.
-20
-40
Pooled
May
Taverner
Brown
Austin
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Hypothetical
60
I
II
III
40
20
Rate Difference
0
For patients with Bells palsy there is
insufficient evidence to conclude that steroids
increase or decrease the probability of good
facial functional recovery.
-20
-40
Pooled
May
Taverner
Brown
Austin
Shafshak
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Conclusions

• For patients with Bells palsy...
• Based on consistent results from two class I and
  two class II studies steroids probably increase
  the likelihood of good facial functional recovery
  by about 12 percent.

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Evidence-based Argument

• Question
• Evidence
• Conclusion
• Recommendation

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Relative Value
Benefits
Risks
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Relative Value
Patient Preferences Consensus
Value of Steroids is Large
Good Facial Function Permanent
Steroid Side Effects Temporary
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Strength of Recommendation
Strength of Evidence 2 Class I 2 Class II 2
Class III Value of Benefit/Risk Large Moderate Small Too
close to call
Level of recommend. A. Should be offered B.
Should be considered C. May be considered U. No
recommendation
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Strength of Recommendation
Strength of Evidence 2 Class I 2 Class II 2
Class III Value of Benefit/Risk Large Moderate Small Too
close to call
Level of recommend. A. Should be offered B.
Should be considered C. May be considered U. No
recommendation
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Recommendation

• For patients with Bells palsy...
• oral steroids should be considered to increase
  the probability of good facial functional
  recovery. (Level B)

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Level A Recommendation
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Level C Recommendation
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