Introduction toEvidence-Based Medicine

Bill Cayley Jr MD MDivUW Health Augusta Family Medicine

Objectives

1. Describe the use of evidence in making medical decisions

2. Demonstrate searching for an evidence-based answer to a medical question

What is“evidence-based

medicine?”

Two fundamental questions…

• What is the purpose of medicine?• How do I decide what to do?

You have to know where you’re going before deciding how to get there…

What is the purpose of medicine?

• Patient care• Public health• Research

Improving the quality of patients’ lives…

What is evidence-based medicine?

Evidence based medicine is the conscientious, explicit, and judicious use of current best

evidence in making decisions about the care of individual patients.

Sackett, et al. BMJ 1996;312:71-72

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

external evidence with which to answer our clinical questions…

EBM – a short history…

• JAMA 1992“EBM: a new approach…”

• JAMA 1993 – 2000“Users' Guides to the

Medical Literature”

• 1990s – 3 trends– Systematic reviews– Search engines– Knowledge distillation

and “push” services

Classification of evidence

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-AnalysisRandomized Controlled Trial

Uncontrolled TrialCase SeriesAnecdote

Meta-AnalysisRandomized Controlled Trial

Uncontrolled TrialCase SeriesAnecdote

More systematic observation ► better evidence

Integrating evidence & practice

What type of outcome measures?

• Surrogate markers of disease:– Hb A1c, cholesterol, blood pressure

• Stage or extent of disease:– Diabetic ulcers, angiographic CAD, stroke

• Patient-oriented outcomes:– Mobility, suffering, longevity– Morbidity and mortality

Patient or disease oriented?• Disease-Oriented Outcomes. – Intermediate, histopathologic, physiologic, or surrogate

results– Examples: blood sugar, blood pressure, flow rate, coronary

plaque thickness– May or may not reflect improvement in patient outcomes.

• Patient-Oriented Outcomes. – Outcomes that matter to patients and help them live

longer or better lives– Examples: including reduced morbidity, reduced mortality,

symptom improvement, improved quality of life, or lower cost

Which outcomes????

• Topical antibiotics for bacterial conjunctivitis may improve early and late resolution rates, but nearly all cases ultimately have complete remission.

• Br J Gen Pract. 55: 962-4.

• Digoxin for symptomatic heart failure provides no significant difference in mortality but is associated with lower rates of hospitalization and of clinical deterioration.

• J Card Fail. 10:155-64.

• Long-acting beta-2 agonists for asthma are effective in reducing symptoms but may increase mortality or exacerbations.

• Cochrane Database of Systematic Reviews 2008, Issue 3. Art. No.: CD006363.

SORT

When guidelines conflict…

Questions of evidence• Were the clinical questions

different?• Were different studies

considered?• Were the results analyzed

differently?• Was the quality of evidence

assessed differently?

Questions of outcomes• Did the effect estimates for

important outcomes differ?• Did judgments about

evidence quality differ?• Were health consequences

weighed differently?• Were economic

consequences considered differently?

Systems applications

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)

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)?

• 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.

Finding Evidence-based Answers

• Woolever DR. The art and science of clinical decision making. Fam Pract Manag. 2008 May;15(5):31-6. PMID: 18546805 (http://www.aafp.org/fpm/20080500/31thea.html)

• Krumholz H, Lee T. Redefining Quality -- Implications of Recent Clinical Trials. N Engl J Med 2008 358: 2537-2539 (http://content.nejm.org/cgi/content/full/358/24/2537)

• Ebell MH. How to find answers to clinical questions. Am Fam Physician. 2009 Feb 15;79(4):293-6. PubMed PMID: 19235495. (http://www.aafp.org/afp/2009/0215/p293.html)

For further reading…

In short… EBM is the conscientious,

explicit, and judicious use of current best evidence in

making decisions about the care of individual patients.

EvidenceSystematic observation =

high-quality evidence

Patient-oriented evidencepreferable to

Stage of diseasepreferable to

Surrogate markers