Applying Evidence in Practice: Critically Appraised Topics CATs

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Applying Evidence in Practice Critically
Appraised Topics (CATs)
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EBM Approach - Review

• Every patient encounter uncovers informational
  needs
• EBM challenges us to
• translate needs into answerable questions
• find evidence to answer them
• appraise evidence for validity
• integrate/apply evidence in practice
• evaluate performance

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Review, contd

• Background
• Asks for general information about a disorder
  (Who What Where When Why How)
• Foreground
• Asks for specific information about managing
  patients with a disorder

Foreground
Background
Experience with condition
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Review Places where evidence may be found

• Background Questions
• Textbooks
• Up-to-Date
• MDConsult
• Review articles

• Foreground Questions
• PubMed
• SUMSearch
• Medical librarians

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The EBM approach in action An example

• You learn that one of your favorite patients (54
  yo man, DM) from continuity clinic died suddenly
  at home. You admitted him 6 months ago to the CCU
  for acute IWMI. Wondering if you did everything
  you could, review of your notes confirms he had
  no complications, but BG was poorly controlled
  during the stay. You wonder if having treated his
  DM more aggressively in acute and immediate
  post-MI setting would have helped.

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Uncertainty

• Tight control improves microvascular
  complications
• vs.
• Insulin ?atherogenic
• Hypoglycemia results in tachycardia may increase
  O2 demands and may expose patient to extension of
  infarct

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The question

• Among diabetic patients with AMI, does tight
  control of their blood sugar reduce mortality?
• Background or foreground?
• Where would you look first?

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Finding the evidence

• MeSH terms
• diabetes mellitus AND myocardial infarction
• limit by publication type (RCT)

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Evaluating the evidence

• Randomization?
• Assignment list concealed?
• All patients accounted for at the end?
• Intention to treat analysis?
• Blinded outcome ascertainment?
• Co-Interventions?
• Were the groups similar?

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Is the evidence important?

• The number of patients that must be treated with
  high intensity insulin therapy for at least 3
  months to prevent one death within a year
• calculated as
• NNT1/(absolute risk reduction ARR)

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Critically Appraised Topic (CAT)

• A means of applying evidence to patients we
  see/problems we encounter
• Starts with a specific informational need
• Serves as a resource for future patients with
  similar issues
• Can (should) be updated

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The problem with CATs

• Individual CATs can be wrong
• Bad evidence, errors, miscalculations
• Information retrieved overly specific
• Patients dont just have one problem
• Information has a short shelf-life
• Old evidence

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Creating a CAT
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Take home messages

• Informational gaps inevitable
• Practice ideally based on evidence
• Finding appraising evidence not so difficult
• Tools are available to organize your findings and
  to assist in its application

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Resources

• Evidence for foreground questions
• PubMED www.ncbi.nlm.nih.gov/entrez/query.fcgi
• SUMSearch sumsearch.uthscsa.edu
• Worksheets to appraise evidence
• www.cebm.net/downloads.asp
• CAT databases at www.cebm.net
• CATmaker (freeware) at
  www.cebm.net/catmaker.asp

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Good luck with your CAT!