evidence-based nutrition practice
TRANSCRIPT
Evidence-Based Nutrition Practice
Applying the Concepts of EBP to Pediatric Nutrition Practice
(with thanks to Donna Johnson)
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.
Two Principles for Evidence Based Practice
Evidence alone is never enough to make a clinical decision (or a decision about guidelines or evidence)
Decisions & Recommendations should be guided by a hierarchy of strength of evidence
“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 Evidence-Base Practice?
Clinicians need information MDs said
» they need it twice a week,» they get it from our text books & journals.
RD’s said» They need it 5 times a week» They search the literature 5 times a month
Clinicians really need information!
If shadowed: they need it up to 60 times per week but only
actually find 30% of what they need 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» “my textbooks are out of date”» “my journals too disorganized”
Medical textbooks are out-of-date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.
Many Traditional Interventions are Out of Date: Ex. Infant GERD
Effective?
Placing in elevated prone position No
Placing in infant seat No
Thickening formula with infant cereal
No
Changing protein content of formula
No
Use of pacifier Unclear
5% vs. 10% dextrose water SlightlyCarroll et al. Arch Ped Adoles Med. 2002
Why don’t RDs seek out the best evidence?
Lack of time Lack of skills for critically appraising the
literature Discomfort with going against traditional
institutional practice
Thomas et al. J Hum Nutr Diet. 2003
Three solutions
1 Carefully research each clinical question that comes our way
2 Seek and apply evidence-based medical summaries generated by others
3 Accept evidence-based practice protocols developed by our colleagues.
Process of EB Practice
1. Define the question2. Plan and carry out search of the
literature3. Critically appraise the literature4. Apply the results to your practice5. Evaluate your performance
Step 1: Define Question -- PICO
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
Articles & Reviews Medline
Meta-analysis Medline, Cochrane
Practice Guidelines Nat’l Clearinghouse
Sytematic Reviews Cochrane, EBM journals
Step 3: Critically Appraise
Basic Introduction and Tutorial at:
http://healthlinks.washington.edu/hsl/classes/evidence/
ADA Quality Indicators
Design appropriate to hypothesis Inclusion & exclusion criteria Sample size Key quality indicators for each study
design type (ex randomized trials or meta-analysis)
Step 4: Apply Results
Within context of individual patient preferences, values and rights (or population resources, values and culture)
Evidence, Values, and Resources
Values
Evidence Resources
The Strength of the Evidence Depends on the Rigor of the Studies
Randomized Controlled Clinical Trial Cohort Study Case-control Study Cross Sectional Study Meta-analysis
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 StudyAdvantages DisadvantagesQuick and cheap Reliance on recall to determine
exposure
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
Meta-analysis
Quantitative method of combining the results of independent studies
Larger sample size and stronger summaries and conclusions
The Five Strengths of Evidence1. Strong Evidence from at least one systematic review of
multiple well-designed RCT2. Strong evidence of at least one well designed RCT of
appropriate size3. Evidence from well designed trials without randomization,
single group pre-post, cohort, time series or matched case control
4. Evidence from well designed non-experimental studies from more than one research group
5. Opinions of respected authorities based on clinical evidence, descriptive studies or reports of expert committees
Systematic Reviews
Identify problem area or area of uncertainty Formulate question Search for evidence Select relevant evidence Abstract findings and evaluate reports Form recommendations Summarize the strength of the evidence
supporting the recommendation Disseminate the findings
EB Review: Example
Huang R-C, Forbes DA, Davies MW Feed thickener for newborn infants with gastro-oesophageal reflux (Cochrane Review). In: The Cochrane Library, Issue 2, 2004. Chichester, UK: John Wiley & Sons, Ltd.
Background
Gastro-oesophageal reflux (GOR) is common in newborn infants. A common first line management is the use of feed thickeners.
The prevalence of excessive GOR in children is approximately 8%, as diagnosed on 24 hour ambulatory pH manometry studies in an unselected healthy infant population. Symptomatic regurgitation alone is more common and has been found to occur in 18% of the general infant population
Step 1: Define Question
P - Patient and disease
I - Intervention
C - Comparative intervention (optional)
O - Outcome
P = Newborn infants with GOR & preterm infants up to 44 weeks
I = Thickeners of all types including rice, gum, or flour based, added to all types of milk including formula and human milk
C = Non-thickened feeds
O = signs and symptoms of reflux, 24 hour ambulatory pH monitoring and/or oesophagitis on biopsy
Step 2. Search for EvidenceWe searched MEDLINE from 1966 to December
2001, the Cochrane Controlled Trials Register, The Cochrane Library, Issue 1, 2002. CINAHL from 1982 to December 2001, and conference and symposia proceedings published in Pediatric Research 1990 to
1994. We also searched conference proceedings for the European Society for Paediatric Gastroenterology and Nutrition (ESPGAN) and the North American Society for Pediatric Gastroenterology and Nutrition (NASPGAN) from 1994 to December 2001. We did not restrict the searches to the English language.
Selection Criteria
All randomised controlled trials that examine the effects of thickening formulas on treating gastro-oesophageal reflux in neonates. The eligible studies were to compare thickened feeds to no intervention (unthickened feeds).
Step 3. Critically appraise the literatureKey Criteria: blindness of randomisation blindness of intervention completeness of follow up blinding of outcome measurement For individual trials, mean differences (and 95%
confidence intervals) were reported for continuous variables
For categorical outcomes the relative risk and risk difference (and 95% confidence intervals) were reported
Data collection and analysis
Two independent reviewers identified potential studies from the literature search. Quality was independently assessed by two independent reviewers.
Study Reason for exclusion
Bailey 1987 Patients' ages ranged from 4 days to 14 months. This was a cross over study in which each patient received both thickened and unthickened feeds, but it does not appear to be a randomised cross over trial.
Carcassonne 1975
No control group was used. The age group ranged from 40 days to five years. The patients used had anatomical abnormalites, severe burns or brain tumours.
Gouyon 1989 This study evaluated smectite in newborn infants with gastroesophageal reflux. It was rejected because of the lack of randomisation and use of further "thickeners" in some patients in both intervention and placebo group on the basis of undefined symptoms. Gouyon 1988 is an abbreviated report of the same study.
Greally 1992 The study population was aged between 2 and 18 months. Infants were randomised to receive either cisapride or gaviscon/carobel. There was no placebo group.
Khoshoo 2000
Age range was from 4 to 10 months. Not a RCT.
Le Luyer 1992
The study group ranged in age from 2 weeks to 57 months. Not a RCT (no control group). Patients were divided into two groups using different doses of a thickener (sodium alginate) without randomisation.
Miller 1999 This study was rejected on the basis of the age group encompassing 0 to 12 months. The outcome data for newborn infants could not be separated from the data of older infants.
Orenstein 1987
Ages were between 4 to 34 weeks of age. This was a cross over study, not a RCT. Each patient received both thickened and unthickened feeds.
Vandenplas 1994
Ages ranged from 1 week to 4 months old. The outcome data for newborn infants could not be separated from the data of older infants.
Weldon 1972 Not a RCT. No control group.
Main Results
No studies fulfilled the requirements for inclusion in the systematic review.
Reviewers' conclusions
There is no evidence from randomised controlled trials to support or refute the efficacy of feed thickeners in newborn infants with GOR. Given the absence of evidence, we cannot recommend using thickening agents for management of GOR in newborn infants
Step 4. Apply resultsImplications for practice
At present, there is no evidence from randomised
controlled trials to support or refute the efficacy of feed thickeners in newborn infants with GOR. Although thickening feeds is a simple and cheap manoeuvre, there
are some theoretical side effects of this treatment such as delayed gastric emptying with increased caloric density of feed. Therefore, given the absence of evidence, we do not recommend using thickening agents for management of GOR in the neonatal population.
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.update-software.com/clibng/cliblogon.htm
Can search and review abstracts for free Full text requires subscription
Cochran Database of Systematic Reviews (examples – 51 nutrition)
Dietary interventions for PKU Carnitine supplementation of parenterally fed
neonates Feed thickener for newborn infants with
GER Vitamin A supplementation for preventing
morbidity and mortality in very low birthweight infants
Formula milk vs. preterm human milk for feeding preterm or LBW infants
Cochran Database of Systematic Reviews (examples – 51 nutrition)
Growth monitoring in children Fat supplementation of human milk for
promoting growth in preterm infants Gastrostomy feeding versus oral feeding alone
for children with cerebral palsy Multicomponent fortified human milk for
promoting growth in preterm infants Enteral nutritional therapy for induction of
remission in Crohn's disease
National Guideline Clearinghousehttp://www.guideline.gov/
examples: Early discharge of the term newborn (bottle and breast-feeding; National Assoc Neonatal Nurses) Nutrition practice guidelines for type 1 and type 2
diabetes mellitus (ADA) Guidelines for the evaluation of food allergies
(American Gastroenterological Association) Bariatric
surgery for severely overweight adolescents: concerns and recommendations.
340 with “nutrition”; 60 with peds nutrition
National Guideline Clearinghousehttp://www.guideline.gov/
ADA currently has 12 guidelines here (ex.): chronic kidney disease gestational diabetes hyperlipidemia MNT type 1 and type 2 diabetes) hypertension – older adults
Most expected to be added in the future
Haynes & Haines, BMJ 1998