- Evidence Based Medicine- Evidence Based Medicine(EBM)(EBM)

Arnuparp LekhakulaDepartment of Internal Medicine

Faculty of MedicinePrince of Songkla University

Scope of Presentation Scope of Presentation

• Why EBM?• What is EBM?• How to use and practise EMB• Application of EBM• Limitations of EBM

Why Why EBMEBM??

Negative correlation between knowledge ofhypertension and the years since graduation from the medical school

Why EBM? Why EBM?• Paradigm shift• Evidences create frequent, major changes in the way of patient care• Both our up-to-date knowledge and our clinical performance deteriorate with time• Quality of health care• Second opinion• Patient education• Cost of health care• Third party

Why EBM? Why EBM?• Eyepatches for corneal abrasion

• Anti-arrhythmic agent : Encainide and flecainide - suppress ventricular arrhythmia

• Steroids in prematurity

No benefit

Higher mortality rate than control?Outcome

Beneficial effect

What is What is- Evidence Based Medicine?- Evidence Based Medicine?

Evidence-Based Evidence-Based MedicineMedicine

The practice of EBM is the integration of individual clinical expertise

with the best available external clinical evidence

from systematic research

and patient’s values and expectations

Assumption of the Old Paradigm Assumption of the Old Paradigm

• Clinical experiences are a valid way for clinical practice • Pathophysiologic principles are adequate guides for clinical practice• Assessment of evidence is adequate through thorough traditional medical training plus the use of common sense• Experts are authority who should be consulted in solving clinical problems

Solving Problems Solving Problems under Old Paradigm under Old Paradigm

• Reflect on own clinical experiences• Reflect on underlying pathophysiology• Consult an updated textbook• Ask content experts• Read introduction and discussions of journals

Assumption of the New Paradigm Assumption of the New Paradigm

• Clinical experiences are of limited values in decisions about clinical practices

• Pathophysiologic principles can lead to inaccurate judgement about clinical practices because of incomplete understandings of all related principles

Assumption of the New Paradigm Assumption of the New Paradigm

• Assessment of evidence requires knowledge of rules of evidences in addition to training and common sense

• Experts should be challenged to produce evidence on which their recommendations are based

Solving Problems with EBM Solving Problems with EBM• Define a patient problem• Convert the problem into answerable questions• Search literature for the best evidence• Critically appraise that evidence for its validity (closed to the truth) and usefulness (clinical applicability)

• Apply the results back to the patient• Evaluate our performance

- Evidence Based Medicine- Evidence Based Medicine

Clinical problemBuilding a good question

Carrying out anefficient, thoughtfulsearch of evidence

Choosing the bestevidence from the

search output

Applying the evidenceto the patient

Critically appraisingthe evidence

How to use and How to use and practise EBM? practise EBM?

Clinical Questions Clinical Questions Arise from : Arise from :• Clinical findings• Etiology• Differential diagnosis• Diagnostic test• Prognosis• Clinical prediction• Therapy• Prevention• Economics

Building a Good Question Building a Good Question‘PICO’

PP atientII nterventionCC omparisonOO utcome

Weighing the Evidence Weighing the Evidence

• Validity (Is it good and true?)

• Importance (Is it worth attention?)

• Relevance (Is it worth putting in practice?)

Two Key Components of EMB Two Key Components of EMB

• Hierarchy of evidencesClinical researchPhysiological studies involving

animals & non-clinical outcomes Clinical experiences

• Decision making Application of evidences Determinants of actions

Nature of Evidences Nature of Evidences• Clinical Experiences Unsystematic observations Varying degree of bias

• Physiologic Evidences Highly systematic & strict scientific rules Limited generalization and inference Different from clinical outcomes• Clinical Research Systematic clinical observation Strategies to deal with bias

SystematicReview

-Meta AnalysisRCT

Cohort-Case Control

-Cross sectional Case Reports

Hierarchy of Evidence Hierarchy of Evidence

• Learning how to practise EBM

• Seeking and applying evidence-based summaries generated by others

• Accepting evidence-based practice protocols developed by colleagues

Three EBM Strategies for Three EBM Strategies for - -Keeping Up to date - -Keeping Up to date

3 Different Modes of 3 Different Modes of PracticePractice

“Searching & appraising” provides E-B care, but is expensive in time

and resources “Searching only”

much, quicker, and if carried out among E-B resources, can provide E-B care

“Replicating” the practice of experts quickest, but may not distinguish evidence-

based from ego-based recommendations

Patients can benefitPatients can benefit Even if <10% of clinicians are capable of

practicing in the “searching & appraising” mode (5% of GPs)

As long as most of them practice in a “searching” mode within high-quality evidence sources (70-80% of GPs): Cochrane Library, E-B Journals, E-B

Guidelines, etc

Cochrane Systematic Reviews (522; another 500 in preparation)

Database of Abstracts of Reviews of Effectiveness (1895)

Registry of Randomised Controlled Trials (218,355)

EBM in Medical Training EBM in Medical Training• Encourage learning• Challenging• Decreased the knowledge gap between trainee and their teachers• Increased the trainees’ confidence and fostering life-long self-directed learning

Limitation of Limitation of- Evidence Based Medicine- Evidence Based Medicine

• RCT gives average probability and not the possible ranges of outcomes

• Patient’s choices informed by facts but influenced by personality and preference

• Bias in research in posing questions and getting answers

• Bias in publication

The Limits of Evidence The Limits of Evidence

• Incomplete and contradictory evidence

• Population effectiveness versus individual effectiveness

• Difficulty of searching evidence in emergency

• Force feeding by EBM may antagonize many

The Limits of EBM The Limits of EBM

• EBM ignores clinical experience and clinical intuition

• Understanding of basic investigation and pathophysiology plays no part in EBM

• EBM ignores standard aspects of clinical training, such as history taking and physical examination

Misapprehensions about EBM Misapprehensions about EBM

- Evidence Based Medicine- Evidence Based Medicine

• is not “everybody already is doing it”• is not subject matter in the textbook• will not produce new findings• will not produce better evidence• is not “cook-book” medicine• is not restricted to randomized trials and meta-analysis

Filter of EBM Filter of EBM

Clinical knowledge, experience and guts

Patient’spreference

Best Evidence Best Evidence

Clinical decision

“ Absence of evidence” is not

“ Evidence of absence”