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.