Evidence-Based Medicine Applying the Concepts to Pediatric Nutrition Practice and Consultation.
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Transcript of Evidence-Based Medicine Applying the Concepts to Pediatric Nutrition Practice and Consultation.
Evidence-Based Medicine
Applying the Concepts to Pediatric Nutrition Practice and
Consultation
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
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.
Evidence Based Medicine is Not:
Cook-book medicine Cost cutting medicine Restricted to randomized trials and
meta-analysis
“If no randomized trials have been carried out for our patient’s predicament, we follow the trail to the next best external evidence and go from there.”
Sacket et al. BMJ 1996
Why EBM?
Clinicians need information If asked:
» we need it twice a week,» we get it from our text books & journals.
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» “my textbooks are out of date”» “my journals too disorganized”
Medical textbooks are out-of-date
Fail to recommend Rx up to ten years after it’s been shown to be efficacious.
Continue to recommend therapy up to ten years after it’s been shown to be useless.
Three solutions
Clinical performance can keep up to date:1 by learning how to practice evidence-
based medicine ourselves.2 by seeking and applying evidence-based
medical summaries generated by others.3 by accepting evidence-based practice
protocols developed by our colleagues.
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
Step 1: Define Question
P - Patient and disease
I - Intervention
C - Comparative intervention (optional)
O - Outcome
Step 2: Search for Evidence
Translate PICO Question into a searchable question
Establish a search strategy» key concepts» boolean operators» synonyms» prioritize» limit
Step 2: Search for Evidence
Sources Tools
Reviews Medline
Meta-analysis Medline, Cochrane
Practice Guidelines Nat’l Clearinghouse
Sytematic Reviews Cochrane, EBMjournals
Step 3: Critically Appraise
http://healthlinks.washington.edu/help/evidence/
Step 4: Apply Results
Within context of individual patient preferences, values and rights
Evidence, Values, and Resources
Values
Evidence Resources
The Strength of the Evidence Depends on Study Design
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
Randomized Controlled Clinical Trial
Advantages Disadvantages
Unbiaseddistribution ofconfounders
Expensive
Blinding more likely Volunteer bias
Randomizationfacilitates analysis
Ethically problematicat times
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
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
Cohort StudyAdvantages Disadvantages
Ethically safe Controls may be hard to ID
Subjects can be matched Exposure may be linked to aconfounder
Can established timing of events Blinding is difficult
Eligibility and outcomeassessment standardized
Ramdomization not present
Easier and cheaper than RCT Large sample or long FU may beneeded
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
Case-control Study
Advantages Disadvantages
Quick and cheap Reliance on recall to determineexposure
Good for raredisorders or longlag
Confounders
Selection of control groups isdifficult
Fewer subjects thanin cross-sectional
Potential selection bias
Cross Sectional Study
Observation of a defined population at a single point in time or time interval
Exposures and outcomes determined at same time
Cross Sectional Study
Advantages Disadvantages
Cheap and simple Can’t establish causality
Ethically safe Recall bias
Confounders may beunequally distributed
Group sizes may beunequal
Study Design
Cross Sectional - association Case Control: exposure outcome Cohort: exposure outcome Randomized controlled trial
Meta-analysis
Quantitative method of combining the results of independent studies
synthesizing summaries and conclusions
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
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.”
EBM Review: Example
A Systematic review of nonpharmacological and nonsurgical therapies for gastroesphageal reflux in infants. Carroll et al. Arch Ped Adol Med. Feb 2002;156:109.
Step 1: Define Question
P - Patient and disease
I - Intervention
C - Comparative intervention (optional)
O - Outcome
P: Patient and Disease
Patient = infants
Disease = GERD
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
C. Comparative Intervention
Carob bean gum compared to rice flour
O. Outcome“Effect on reflux”
Included:» reflux duration (pH probe)» reflux frequency (pH probe)» clinical score» emesis
Search for Evidence
Medline, EMBASE, Cochrane, others search terms: gastroesophageal reflux
disease and infants (>2500 articles) excluded: non-clinical trials, drug or
surgical therapy included, study included infants with compound medical problems/prematurity
10 RCT met selection criteria
Critically appraise the literature
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.
Example:Thickening with rice flour/cereal - 2 studies
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.
Apply results
“Many conservative measures commonly used to treat GERD in infants have no proven efficacy.”
Medline
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed
Under “Limits” can select:» Review» Meta-analysis» Practice Guidelines» Randomized Controlled trial
Cochran Database of Systematic Reviews
http://www.cochranelibrary.com/enter Can search and review abstracts for free
Full text requires subscription
National Guidelines Clearing House
http://www.guideline.gov/
Haynes & Haines, BMJ 1998