View
19.442
Download
1
Category
Preview:
DESCRIPTION
Citation preview
Evidence Based Medicine
Module 1: Introduction to EBMModule 2: Applying EBM--DiagnosisModule 3: Applying EBM--Treatment
Prepared by:
Jennifer Kleinbart, MD, Asst. Professor of Medicine,Director, EBM CurriculumEmory University School of Medicine
Mark V. Williams, MD, Associate Professor of Medicine, Director, Hospital Medicine UnitEmory University School of Medicine
Lawrence Blond, MD, Associate Director Graduate Medical Education, Alton Ochsner Medical Foundation
Evidence Based Medicine
An evidence-based approach to answering clinical questions
Outline
Introduction
What is EBM?
Why do we need it?
How to use EBM in daily practice
EBM resources
Bloodletting
The cure for hot, moist diseases
Pierre Louis (1787-1872)Inventor of the “numeric method” and the “method
of observation”
Found that, on average, patients who were bled did worse than those who were not.
Overall Results (n=77)
“Experimental”Group
“Control”Group
AbsoluteRisk Reduction
Bled Early Bled Late Difference
Mortality 44% 25% - 19%
William Osler (1849 -1919)First “attending physician” at Johns Hopkins
Hugely influential textbook author, believed that most drugs in his day were useless, but still advocated blood-letting in some cases.
But….
We practice EBM today
Patient: Mr. A
Mr. A is a 60 year old presenting with 1 hour of retrosternal chest pain. ECG shows lateral ST-elevation consistent with acute MI.
QUESTION: In patients with acute MI, does treatment with aspirin reduce mortality?
What is the best evidence?
Evidence: 1988 Reduction of mortality in acute myocardial
infarction with streptokinase and aspirin therapy. Results of ISIS-2. – Patients with acute MI treated with ASA vs.
placebo had a significant 23% relative risk reduction in five-week cardiovascular mortality, with an absolute risk reduction of 11.8% to 9.4%.
– The combination of SK and ASA resulted in a 42% relative risk reduction in cardiovascular mortality after five weeks compared with the placebo.
Application: 1997
How many patients receive ASA following acute myocardial infarction? 463 patients in the ER with a definitive diagnosis of acute MI– Aspirin was not given to 55%!!!– 78% of patients who did receive aspirin
received it more than 30 minutes after arrival to the emergency department.
Annals of Intern Medicine. Jul 1997;127(2):126
EBM MisconceptionsFALLACY FACT
EBM is useless when there is no good evidence
EBM means appropriately using the best available evidence to care for patients
EBM is algorithms that ignore clinical judgment/expertise
Clinical judgment must be used in deciding how to apply the evidence
EBM is just numbers and statistics
EBM is not numbers in a vacuum – the evidence must be individualized to each patient
EBM - What is it?
Clinical Expertise
Research Evidence
Patient Preferences
Why EBM?Caring for patients creates the need for
clinically important information– Diagnosis….Therapy….Prognosis
Knowledge deteriorates with time: Practitioners practice what they learned during residency training– EBM: goal of life-long self-directed
learning
Why EBM?
New evidence often changes clinical practice
Prospective learning from reading journals and going to conferences is important, but not sufficient – Impossible to prospectively acquire all
information necessary to treat all future patients
Besieged with Information
More than 3800 biomedical journals in MEDLINE
More than 7300 citations added weekly
Lag period – Publication of research findings– Implementation in clinical practice
Besieged with Information
All studies not equally well designed or interpreted– Adding expert synthesis and
analysis cantruly help busy clinicians
So, how does it work?
EBM Method
Acquire the best evidence
Appraise the evidence
Applyevidence to patient care
Assess your patient
Ask clinical questions
EBM Method
Assess Your Patient
HistoryPhysical examinationObjective data – labs, x-rays
• Formulate differential diagnosis• Pretest probability of disease
Ask Clinical Questions
Patient/Population OutcomeIntervention/
Exposure Comparison
Components of Clinical Questions
In patients withacute MI
In post-menopausal
women
In women withsuspected
coronary disease
does early treat-ment with a statin
what is the accuracy of
exercise ECHO
does hormonereplacement
therapy
compared to placebo
compared to exercise
ECG
compared to noHRT
decrease cardio-vascular mortality?
for diagnosingsignificant
CAD?
increase therisk of
breast cancer?
Acquire the Best Evidence Where do you find high-quality evidence?
– Textbook (print or online)– Medline or PubMed search: find and review articles– Pre-appraised evidence
Best Evidence Clinical Evidence (Therapy only) Cochrane Collaboration (Therapy only) UpToDate
Which source enables you to find answersmost quickly?
Appraise the Evidence
Are the results valid?
What are the results?
Can we apply the results to our patient?
Appraise the Evidence
Determine if evidence is unbiasedor flawed– Critically appraise articles yourself– Used a source that appraises trials for you
Best EvidenceClinical Evidence Cochrane LibraryUpToDate
Apply the Evidence
Evidence must be applied to each individual patient– Is your patient similar enough to those
studied?– Do benefits outweigh harms?– Cost– What are your patient’s values and
preferences?
Rules of Evidence
All evidence is not created equal.Evidence alone never makes
clinical decisions.Values always influence decisions.
Recommended