Evidence-Based%20Medicine

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Evidence-Based Medicine

• Applying the Concepts to Pediatric Nutrition
  Practice and Consultation

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What evidence-based medicine is

• Evidence-based medicine is the conscientious,
  explicit and judicious use of current best
  evidence in making decisions about the care of
  individual patients.
• Sacket et al. BMJ 1996

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What evidence-based medicine is

• The practice of EBM requires the integration of
• individual clinical expertise
• with the
• best available external clinical evidence from
  systematic research.

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Evidence Based Medicine is Not

• Cook-book medicine
• Cost cutting medicine
• Restricted to randomized trials and meta-analysis

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• If no randomized trials have been carried out
  for our patients predicament, we follow the
  trail to the next best external evidence and go
  from there.
• 
  Sacket et al. BMJ 1996

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Why EBM?

• Clinicians need information
• If asked
• we need it twice a week,
• we get it from our text books journals.

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Clinicians really need information!

• If shadowed
• they need it up to 60 times per week but only
  30 of it
• and that comes from passers-by
• my textbooks are out of date
• my journals too disorganized

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Medical textbooks are out-of-date

• Fail to recommend Rx up to ten years after its
  been shown to be efficacious.
• Continue to recommend therapy up to ten years
  after its been shown to be useless.

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Three solutions

• Clinical performance can keep up to date
• by learning how to practice evidence-based
  medicine ourselves.
• by seeking and applying evidence-based medical
  summaries generated by others.
• by accepting evidence-based practice protocols
  developed by our colleagues.

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Process of EBM

• Define the question
• Plan and carry out search of the literature
• Critically appraise the literature
• Apply the results to your practice
• Evaluate your performance

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Step 1 Define Question

• P - Patient and disease
• I - Intervention
• C - Comparative intervention (optional)
• O - Outcome

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Step 2 Search for Evidence

• Translate PICO Question into a searchable
  question
• Establish a search strategy
• key concepts
• boolean operators
• synonyms
• prioritize
• limit

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Step 2 Search for Evidence
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Step 3 Critically Appraise

• http//healthlinks.washington.edu/help/evidence/

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Step 4 Apply Results

• Within context of individual patient preferences,
  values and rights

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Evidence, Values, and Resources
Values
Evidence
Resources
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The Strength of the Evidence Depends on Study
Design
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Randomized Controlled Clinical Trial

• Involves one or more test treatments and a
  control treatment
• Specified outcome measures for evaluating the
  intervention
• Bias free method for assigning treatment

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Randomized Controlled Clinical Trial
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Confounding Variable

• An extrinsic factor that is associated with the
  predictor variable and a cause of the outcome
  variable.
• Hulley and Cummings, Designing Clinical Research

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Cohort Study

• Identification of two groups
• one received exposure of interest
• one did not receive exposure
• Follow cohort through time to observe the outcome
  of interest

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Cohort Study
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Case-control Study

• Identify patients who have the outcome of
  interest (cases)
• Identify controls without the same outcome
• Look back to see if they had the exposure of
  interest

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Case-control Study
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Cross Sectional Study

• Observation of a defined population at a single
  point in time or time interval
• Exposures and outcomes determined at same time

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Cross Sectional Study
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Study Design

• Cross Sectional - association
• Case Control exposure outcome
• Cohort exposure outcome
• Randomized controlled trial

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Meta-analysis

• Quantitative method of combining the results of
  independent studies
• synthesizing summaries and conclusions

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The Five Strengths of Evidence

• Strong Evidence from at least one systematic
  review of multiple well-designed RCT
• Strong evidence of at least one well designed RCT
  of appropriate size
• Evidence from well designed trials without
  randomization, single group pre-post, cohort,
  time series or matched case control
• Evidence from well designed non-experimental
  studies from more than one research group
• Opinions of respected authorities based on
  clinical evidence, descriptive studies or reports
  of expert committees

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Barriers and BridgesHaynes and Haines, BMJ 1998

• Preliminary studies far outnumber definitive
  ones, and all compete in the medical literature
  for the attention of readers.
• Models for critically appraising evidence have
  been developed, but applying these is time
  consuming.

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EBM Review Example

• A Systematic review of nonpharmacological and
  nonsurgical therapies for gastroesphageal reflux
  in infants. Carroll et al. Arch Ped Adol Med.
  Feb 2002156109.

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Step 1 Define Question

• P - Patient and disease
• I - Intervention
• C - Comparative intervention (optional)
• O - Outcome

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P Patient and Disease

• Patient infants
• Disease GERD

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I. Intervention (s)

• Placement upright in an infant seat
• Elevating the Head
• Pacifier Use
• Thickening food with rice flour
• Thickening food with carob bean gum preparation
• Changing composition of Formula
• Changing caloric density or osmolality

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C. Comparative Intervention

• Carob bean gum compared to rice flour

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O. Outcome

• Effect on reflux
• Included
• reflux duration (pH probe)
• reflux frequency (pH probe)
• clinical score
• emesis

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Search for Evidence

• Medline, EMBASE, Cochrane, others
• search terms gastroesophageal reflux disease and
  infants (gt2500 articles)
• excluded non-clinical trials, drug or surgical
  therapy included, study included infants with
  compound medical problems/prematurity
• 10 RCT met selection criteria

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Critically appraise the literature
ExampleThickening with rice flour/cereal - 2
studies

• Study one 52 infants randomly received apple
  juice or apple juice with rice flour, placed in
  one of 4 positions, monitored with pH probe for 2
  hours. No differences except that more reflux
  with 30o elevation and rice flour.

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• Study 2. 20 infants with paired feeding
  crossover design given formula with and without
  rice cereal thickening and monitored via
  technetium scintigraphy. No differences on
  reflux, but decrease in frank emesis.

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Apply results

• Many conservative measures commonly used to
  treat GERD in infants have no proven efficacy.

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Medline

• http//www.ncbi.nlm.nih.gov/entrez/query.fcgi?dbP
  ubMed
• Under Limits can select
• Review
• Meta-analysis
• Practice Guidelines
• Randomized Controlled trial

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Cochran Database of Systematic Reviews

• http//www.cochranelibrary.com/enter Can search
  and review abstracts for free
• Full text requires subscription

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National Guidelines Clearing House

• http//www.guideline.gov/

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Haynes Haines, BMJ 1998