Ebm

EVIDENCE BASED MEDICINE

AN INTRODUCTION25-7-2016

What EBM is not ?• Something physicians have been doing for ages.• “Cookbook” medicine.• A tool for administrators and insurers.• Restricted to randomized trials and systematic reviews.• Opposed to patient centered medicine.

What is the need?• Cost• Delay of "bench-to-bedside" research• Managing the primary literature• Counter misleading marketing• Dealing with conflicting results

Why EBM?

What is the need?• Cost• Delay of "bench-to-bedside" research• Managing the primary literature• Counter misleading marketing• Dealing with conflicting results

Why EBM?

increasing pressure to • demonstrate effectiveness of interventions• utilize the most cost effective measures

How do you know what really works or is the most cost effective?

Delay of "bench-to-bedside" research:

Why EBM?

Secondary Research

Routine Clinical Practice

Primary Literature

Years-to-Decades

Delay of "bench-to-bedside" research:

Why EBM?

Secondary Research

Routine Clinical Practice

Primary Literature

Thrombolytic Drugs for acute MI:

6 years from the first Systematic Reviews until most textbooks recommended their use.(Antman, Lau, et al. JAMA 1992)

Delay of "bench-to-bedside" research:

Why EBM?

Secondary Research

Routine Clinical Practice

Primary Literature

Aspirin after acute MI:

Not recommended by expert opinion until 6 years after the first systematic review.(Antman, Lau, et al. JAMA 1992)

Managing the primary literature

Why EBM?

• MEDLINE add 2,000 articles / day from 120

journals • Just within their own fields, physicians would need

to read 19 articles per day, 365 days per year, to keep up with research. (Oxford Center for EBM)

• Not all (~10%) of these articles are considered high quality and clinically relevant. (Oxford)

EBM helps you find the most appropriate article for a specific clinical question.

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500000

1000000

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Biomedical MEDLINE Trials Diagnostic?

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ical

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5,000?per day

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Why do we need to use evidence efficiently?

EBP: informing decisions with the best up-to-date evidence

• Counter misleading marketing

Why EBM?

Pharmaceutical companies invest considerable resources to promote products based on skewed or selective evidence (or emotion appeals through direct-to-consumer advertising). EBM provides tools to help alert clinicians to potentially misleading marketing.(Glasziou, Hayes. The paths from research to improved health outcomes, Evidenced Based Nursing, 2005; 8(2):36-8.)

Dealing with conflicting results

Why EBM?

• Beta-blockers initially avoided after MI due to pathophysiologic reasoning that they would decrease compensatory sympathetic mechanisms

• Later shown to decrease hospitalization & death:

Dealing with conflicting results

Why EBM?

• Based on 16 cohort studies HRT used to be recommended for postmenopausal women to reduce the risk of CHD.

• Women’s Health Initiative show it actually increased the risk of MI, stroke, and venous thromboembolism:

Median minutes/week spent reading about my patients:

Self-reports at 17 Grand Rounds:

• Medical Students: 90 minutes• House Officers : 0 (up to 70%=none)• SHOs : 20 (up to 15%=none)• Registrars: 45 (up to 40%=none)• Sr. Registrars 30 (up to 15%=none)• Consultants:• Grad. Post 1975: 45 (up to 30%=none)• Grad. Pre 1975: 30 (up to 40%=none)

Size of Medical Knowledge

2 million concept names11,000 diseases30,000 abnormalities (symptoms, signs, lab, X-ray,)3,200 drugs

Are we (currently) equipped to tell good from bad research ?

• BMJ study of 607 reviewers• 14 deliberate errors inserted

• Detection rates• Poor Randomisation (by name or day) - 47%• Not intention-to-treat analysis - 22%

Schroter et al

A study of resident's attitude, knowledge and barriers towards the use of evidence based medicine (Resaei et al,2013)

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?

‘Background’ Questions

• About the disorder, test, treatment, etc.

2 components:a. Root* + Verb: “What causes …”b. Condition: “… Pneumonia?”

• * Who, What, Where, When, Why, How

‘Foreground’ Questions• About patient care decisions and actions

4 (or 3) components:

a. Patient, problem, or population

b. Intervention, exposure, or maneuver

c. Comparison (if relevant)

d. Clinical Outcomes

Background & Foreground

Foreground Questions: PICO (5 main questions) 1. How common is the problem? Prevalence

2. Is early detection worthwhile? Screening

3. Is the diagnostic test accurate? Diagnosis

4. What will happen if we do nothing? Prognosis

5. Does this intervention help?

Treatment 5. What are the common harms of an intervention?5. What are the rare harms of an intervention?

Type of Question Suggested best type of Study

Therapy RCT>cohort > case control > case series

Diagnosis Prospective, blind comparison to a gold standard

Etiology/Harm RCT > cohort > case control > case series

Prognosis Cohort study > case control > case series

Prevention RCT>cohort study > case control > case series

Cost Economic analysis

[1.]

Sources for Background Questions :• Textbooks• Handbooks• Manuals

Background Questions

Acquire

Unfiltered

Expert Opinion

Filtered

Acquire

THE EVIDENCE PYRAMID

The 6 Prerequisites for successful Literature Searching

1 •Know how to use a computer/electronic device.

2 •Know the Internet Jargon of Terms.

3 •Know the EBM Jargon of Terms.

4 •Know how to formulate your question.

5 •Know where to go.

6 •Know what to do when you get there: the site’s technical language/know-how.

For Whom?

Chairman Nursing ManagerResident

Clinical DirectorQuality

Nurse

“A 21st century clinician who cannot critically read a study is as

unprepared as one who cannot take a blood pressure or examine the

cardiovascular system.”BMJ 2008:337:704-705