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Evidence Based Medicine (EBM)

Tim FOMEFakultas Kedokteran Universitas Andalas

Introductory Lecture: Objectives

1. What

What is evidence-based medicine?

What does it look like in practice?

2. How

Formulate Clinical Questions

1. Search for Evidence

2. Appraisal of research

3. Apply to clinical problem

What is evidence-based medicine?

“Evidence-based medicine is the integration of best

research evidence with clinical expertise and

patient values”

- Dave Sackett

PatientConcerns

Clinical Expertise

Best research evidence

EBM

What is “EBM” NOT?

What we have always done

“Cookbook medicine”

Only a cost-cutting trick

Only randomized trials

Evidence based medicine IS…

Tracking down the best externalevidence with which to answer our clinical questions…

Life long learning

The hardest conviction to get into the mind of a

beginner is that the education upon which he is

engaged is not … a medical course, but a life

course, for which the work of a few years under

teachers is but a preparation.

– Sir William Osler (1849-1919), from: The Student of

Medicine

How do I decide what to do?

How do I make decisions?

• Dogma: “Natural is best”

• Tradition: “We’ve always done it that way”

• Convention: “Everyone does it this way”

• Evidence-Based: “Evidence supports this way”

How do I decide what to do?

The answer from

EBM…

“…use of current best

evidence…”

Evidence: systematic observation

Meta-Analysis

Randomized Controlled Trial

Uncontrolled Trial

Case Series

Anecdote

Meta-Analysis

Randomized Controlled Trial

Uncontrolled Trial

Case Series

Anecdote

More systematic observation ► better evidence

Integrating evidence & practice

EBM Cycle

Patient problems

Clinical Question

Literature Search

Critical Appraisal

Apply Evidence

Evaluate Application

The EBM Cycle

1. Assess the patient: A clinical question arises from caring for a

patient.

2. Ask the question: Construct a well-built foreground question derived

from the case.

3. Acquire the evidence: Find the answer from the evidence presented

in the medical literature and identify the best resource from among

the many.

4. Appraise the evidence: Appraisal includes validity (closeness to

truth) and applicability (usefulness in clinical practice).

5. Apply: Communicate the evidence to your patient and integrate the

evidence with clinical expertise, patient preference and apply.

6. Self-evaluation: Evaluate the process and outcome.

Clinical Questions

– Ask the question: Construct a well-built

foreground question derived from the

case.

Two Types of Questions are

Generated in the EBM Cycle

Background Questions ask about general knowledge

relating to a condition, diagnostic test or treatment.

• They typically start with who, what, where, when, how, or why.

Foreground Questions ask for specific knowledge to

inform clinical decisions for patient care.

Clinical Questions

Background - “What is it?”

General information on a condition or disease

Foreground – “What do I do for this patient?”

Patient

Intervention/Investigation

Comparison Intervention/Investigation

Outcome (Patient-Oriented)

PICOP = Patient, population or target problem at hand

How would you describe a group of patients similar to your own?What is the condition or disease you are interested in?

I = Intervention

What do you want to do to this patient?Treat, diagnose or observe?

C= Comparison

What is the main alternative (gold standard) to compare with the intervention? Your clinical question does not always need a direct comparison.

O= Outcome

What can you hope to improve, accomplish, measure or affect?What are the relevant outcomes? (morbidity, death, complications)

Richardson WS, Wilson MC, Nishikawa J, Hayward RS. The well-built clinical question: a key to evidence-based decisions. ACP J Club. 1995 Nov-Dec;123(3):A12-3.

Formulating the Foreground Question

The following formula will help construct the question:

In patients [include significant demographics]

with [specify Target Problem ] does [specify

Intervention] or [specify Comparison, if any]

affect [specify Outcome]?

Clinical Questions - “PICO”

Example:

In a 5 year old child with conjunctivitis (patient) will topical antibiotics (intervention) compared to no treatment (comparison) lead to quicker symptom relief (outcome)?

In a 5 year old child with conjunctivitis (patient) will topical antibiotics (intervention) compared to no treatment (comparison) lead to improved cure rates (outcome)?

Question Domains

Foreground questions fall into general question domains.

Each domain is best answered by particular study types.

Study types are powerful limits to finding best evidence.

Question Domain Suggested Best Study Types

Diagnosis RCTs > prospective studies (which make a blind

comparison to the gold standard)

Therapy RCTs > cohort studies > case-control studies

Etiology/Harm RCTs > cohort studies > case-control studies

Prognosis cohort studies > case-control studies

Economic Analysis costs and cost analysis

Literature Search

– Acquire the evidence: Find the answer

from the evidence presented in the

medical literature and identify the best

resource from among the many.

Should I ask a colleague?

Searching: finding good answers?

Searching made easy

Finding Evidence-based Answers

• Trip Database (http://www.tripdatabase.com/)

• Database of Abstracts of Reviews of Effectiveness

(http://www.crd.york.ac.uk/crdweb/)

• DynaMed (http://www.dynamicmedical.com/)

– *Subscription required.

• Essential Evidence Plus (http://www.essentialevidenceplus.com/)

– *Subscription required.

• Cochrane Library (http://www.cochrane.org/)

– *Subscription for full access, abstracts free.

• FPIN (http://www.fpin.org/)

– *Subscription required.

• Clinical Evidence (www.clinicalevidence.com/)

– *Subscription required.

Critical Appraisal

• Appraise the evidence: Appraisal

includes validity (closeness to truth) and

applicability (usefulness in clinical

practice).

Rapid Critical AppraisalIt’s peer-reviewed, therefore it must be OK ????

Which resources do I use to

answer my question?

• Part of the process in answering foreground questions is

understanding how to select resources that yield the best

evidence.

• Understanding the pros and cons of those resources will lead

to information mastery.

• The Evidence Pyramid can help determine where to go.

Evidence Pyramid

Be

st Eviden

ce

Synthesized & Evaluated Literature

Primary Literature

May or May not be Evidence-Based

Provided by HealthLinks, University of Washington, http://healthlinks.washington.edu/ebp/ebptools.html

That depends on the kind of question you are asking.

What kind of information are you after? A systematic review may not be necessary for every situation.

Start at the bottom and work your way up.

There are more Clinical Reference Texts than Systematic Reviews.

Evidence PyramidHow do I use the pyramid?

• Give background information• Help to define the PICO elements• Form the basis of foreground questions• Make up the largest percentage of resources

Start Here: Base Resources

Where do I find them? • Library catalog, discovery tool for clinical texts• http://guidelines.gov• “review article” limit in MEDLINE

• Have the most evidence to support their conclusions• Best for answering foreground questions• Less abundant in the literature• But more clinically relevant for decision making

Top of the Pyramid Resources

How do I find them?• Consult a point-of-care resource such as DynaMed• Search MEDLINE for systematic reviews, meta-analyses or individual study types e.g. RCTs

The “best” evidence depends

on the type of question

Level Treatment Prognosis Diagnosis

I Systematic Review of …

Systematic Review of …

Systematic Review of …

II Randomised trial

Inception Cohort

Cross sectional

III

Apply Evidence

– Apply: Communicate the evidence to your

patient and integrate the evidence with

clinical expertise, patient preference and

apply.

Applying to the individual

• What do the results mean

on average?

• What do they mean for

this individual?

Evaluate Application

• Self-evaluation: Evaluate the process

and outcome.

In short…

EBM is the conscientious, explicit, and judicious

use of current best evidence in making decisions

about the care of individual patients.

Is keeping up to date Mission Impossible?

Bluegreenblog 2006

Review the World Literature Fortnightly**"Kill as Few Patients as Possible" - Oscar London

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Coping with the overload:

three possible things you might try

A. Read an evidence-based

abstraction journal

(and cancel other journals)

B. Keep a logbook of your

own clinical questions

C. Run a case-discussion journal

club with your practice

What are your clinical questions?

• A 35 year old man says his brother recently died of a

ruptured cerebral aneurysm.

He is worried about whether he might have one and

what the chances are that it would rupture.

• A 60 year old women worried about her rheumatoid

arthritis. She asked whether the rheumatoid arthritis

could kill her.

– Do patients with rheumatoid arthritis have higher

mortality?

• You use methotrexate for rheumatoid arthritis

patients. But you are confused is the methotrexate

benefit patients?

– Do patients with rheumatoid arthritis benefit from

methotrexate?-> PICO Table