Evidence-Based Medicine

(EBM)

การแพทยแ์บบองิหลกัฐาน

Chulaporn Limwattananon, PhD

Onanong Waleekhachonloet, PhD

Objectives

To be able to explain the term “evidence-based medicine”

To be able to search for literature

providing evidence-based medicine

To be able to apply knowledge in

evidence-based medicine on

understanding the appropriate use

of drug therapy

Rule 31 – Review the World Literature

Fortnightly*

0

500000

1000000

1500000

2000000

2500000

Biomedical MEDLINE Trials Diagnostic?

Med

ical

Art

icle

s p

er

Year

5,000?

per day

1,500

per day95 per

day

Medic

al Art

icle

s P

er

Year

What is evidence-based

medicine?

“Evidence-based medicine is the integration of

best research evidence with clinical expertise

and patient values”

PatientConcerns

Clinical Expertise

Best research evidence

EBM

Dave Sackett

Level of evidence

Level I: Meta-analysis

Level II: RCT

Level III-1: Controlled trial with rigorous design

but no randomization

Level III-2: Multiple time series with or without

control group, but remarkable findings

Level IV: Expert opinion or descriptive studies

Level of evidence

Level of Evidence

Systematic reviews

WHERE AND HOW CLINICAL QUESTIONS ARISE

1. Clinical findings:

2. Etiology:

3. Clinical manifestations of disease:

4. Differential diagnosis

5. Diagnostic tests

6. Prognosis

7. Therapy

8. Prevention

9. Experience and meaning

10. Improvement

ตวัอย่างการใช้ EBM บญัชยีาหลกัแหง่ชาติ

- Indication, efficacy, safety- Effectiveness- Cost effectiveness- Reimbursement system of other countries (effective list & negative list)

ส านกัหลกัประกนัสขุภาพแหง่ชาต ิ(สปสช)ตวัอยา่งประเดน็- ควรใหม้กีารเบกิ Glucosamine ในผูป้ว่ยสทิธขิา้ราชการหรอืไม่- Vitamin E (100 i.u.) tab ควรเขา้ในบญัชยีาหลกัแหง่ชาตหิรอืไม่- ยากลุ่ม bisphosphonate ควรเขา้ในบญัชยีาหลกัแหง่ชาตหิรอืไม่

advanced Pubmed search, TRIP database, BMJ clinical evidence, Cochrane library, Micromedex Drugdex Drug

Evaluation, Micromedex Drug Interactions, WHO Defined Daily Dose Website, Clinical Pharmacology 2004 CD ROM, Medscape Druginfo, Physician Desk Reference (PDR), Martindale และ BNF

. ตวัอย่าง search strategyท่ีใช้ค้นใน Pubmed

Atenolol[MeSH] AND "Migraine"[MeSH] AND (Randomized Controlled Trial[ptyp] OR Meta-Analysis[ptyp] OR Review,

Academic[ptyp])

1.Evidence based medicine

EBM vs Systematic Review process

EBM Steps (quick & dirty)

1.Ask Question

2.Search 3.Appraise

4.Apply

Time: 90 seconds

< 20 articles

This patient survives!

For pharmacist: daily practice, DIS

Systematic Review Steps

1.Ask Question

2.Search ++++ x 2

3.Appraise x 2

4.Synthesize

5.Apply

Time: 6 months, team

< 2,000 articles

This patient is dead

For lecturer: desk-based, publicable, broad area

Source: Glasziou P http://www.cebm.net/index.aspx?o=1083

Systematic Review VS meta-analysis

A Systematic Review is a review of a clearly formulated question that uses systematic and explicit methods to identify, select and critically appraise relevant research, and to collect and analyse data from the studies that are included in the review.

Statistical methods (meta-analysis) may or may not be used to analyze and summarize the results of the included studies.

Source: Glasziou P http://www.cebm.net/index.aspx?o=1083

Practicing EBM in 5 steps

Step 1: Formulating a well-built question

Step 2: Identifying articles and other evidence-

based resources that answer the question

Step 3: Critically appraising the evidence to

assess its validity

Step 4: Applying the evidence

Step 5: Re-evaluating the application of

evidence and areas for improvement

Step1: PICO Principle

Population or participants Intervention or indicator

Comparator or control

Outcome

“In a 55-year-old man with a 35-year-old history of chronic smoking, would the administration of bupropion as compared to a nicotine replacement therapy (NRT) be a better therapy in causing long-term abstinence from smoking?”

Can you identify each PICO component?

P

I

C

O

Suitable design for specific question

Intervention: Meta analysis, RCT

Risk/etiology: Cohort, case control

Rate/frequency: Cohort, cross sectional

Diagnosis: cross sectional

Prognosis: cross sectional, survival

ตวัอยา่งค าถาม “ผูป่้วยทีไ่ดรั้บการตรวจ fecal occult blood เมือ่เปรยีบเทยีบกบัการไมไ่ดต้รวจ จะชว่ยลดอัตราตายจากการเกดิมะเร็งล าไสใ้หญไ่ดห้รอืไม?่”

PICO

ค าสั่งคน้หา

ค าทีเ่กีย่วขอ้ง ค าเหมอืนอืน่ๆ

P adult, human -

I screening, colorectal cancer

screen, early detection, bowel cancer

C no screening -

O Mortality death*, survival

* เครือ่งหมายดอกจันทน ์หมายถงึ wildcard ใชใ้นการคน้หาอักษรหรอืค าอืน่ๆ ในการประกอบกับค าซึง่ปรากฎอยูแ่ลว้

จากตัวอยา่งค าถามขา้งตน้ สามารถน ามาสรา้งค าสัง่คน้หา คอื (screen* OR early detection) AND (colorectal cancer OR bowel cancer) AND (mortality OR death* OR survival)

Step 2: Database/Resource

Searching General Information (Background) Resources :

provide background information about various

diseases, conditions, and clinical questions. UptoDate:

http://www.uptodate.com/home/index.html

DeGowin‟s Diagnostic Examination

Current Diagnosis and Treatment.Merck Manual of Diagnosis and Therapy

Database/Resource Searching

Filtered Resources:

provide a variety of information backed up with links to the literature and references to the resources Cochrane Database of Systematic Reviews, InfoPOEMS

ACP‟s Pier (Physician‟s Information and Education Resource) National Guideline ClearinghouseNatural Standard Natural Medicine Comprehensive Database

Database/Resource Searching

Unfiltered Resources :

Primary literature

BIOSIS

PsycINFO

CINAHL

Cochrane Library http://www.cochrane.org

Cochrane Database of Systematic

Reviews

Cochrane Controlled Trials Register

(Central Register of Controlled Trials

(CENTRAL)

Database of Abstracts of Reviews of Effectiveness (DARE)

การพจิารณาประสทิธผิลของยา

• ความเชือ่

• ความเห็น

• ความรู ้= ผลจากการวจัิยทีม่คีณุภาพสงู ~ ความจรงิ

• ความจรงิ

Step 3: Critical appraisal:

Intervention

ท่ีมา: slide บรรยายของศ.นพ. วษิณ ุธรรมลขิิตกลุ

Statistical estimation

Population

Random sample

Parameters

Statistics

Every member of the

population has the

same chance of being

selected in the sample

estimation

Critical appraisal:

Intervention

Were the groups of subjects

representative and comparable?

Was the outcome measurement accurate?

Was a placebo used?

Could the results have been due to

chance?

Were the groups of subjects

representative and comparable?

Select subjects randomly

Inclusion/exclusion criteria

Large enough sample size

Were the groups of subjects

representative and comparable?

Equal treatment => the only difference

between the two groups should be treatment

being tested.

Analysis of all subjects => once a subject is

randomised, he or she should be analysed in

the group they are randomised to. This is

called the ‘intention to treat principle’.

Was the outcome measurement

accurate?

Measurement bias

The biases from subjects and outcome assessors

can be overcome by using „blinding‟ => best is

double blind, moderate is single blind, and worst

is not blind.

Measurement error

This occurs if the outcomes are not measured in

the same way for all subjects. It is therefore

important to use exactly the same measurement

strategy and methods for everyone (both the

treatment and control groups).

Was a placebo used?

The „placebo effect‟ is the so-called effect that is

attributable to the expectation that the treatment

will have an effect.

Placebo effect - Trial in patients with chronic severe itching

Cyproheptadine

HCl

Trimeprazine

tartrate

No tratment

Placebo

0

10

20

30

40

50

60

Treatment vs no treatment vs placebo for itching

Itch

ing

scor

e

NO Treatment