4. What Is Evidence-Based Medicine
(EBM)?
“...the conscientious, explicit, and judicious
use of current best evidence in making
decisions about the care of individual
patients.”
Sackett DL, Rosenberg WM, Gray JA, Haynes RB, Richardson WS (1996)
6. ขั้นตอนของ EBM
1. Ask
Questions
2. Access
Evidence
3.
Appraise
Evidence
4. Apply
Evidence
5. Assess
Outcome
1. ASK a clinically-relevant question
ตั้งคาถามจากปัญหาผู้ป่วย
2. ACCESS the best available evidence
ค้นหาข้อมูล
3. APPRAISE its quality & importance
ประเมินค่าของข้อมูล
4. APPLY the evidence in patient care
ประยุกต์ใช้ข้อมูลในผู้ป่วย
5. ASSESS the outcome
ประเมินผล
7. EBM ตามเกณฑ์ National License
ของแพทยสภา (พ.ศ. 2555)
1.2.9 Evidence-based medicine
1.2.9.1 Asking focused questions: translation of uncertainty to an
answerable question
1.2.9.2 Finding the evidence: systematic retrieval of best evidence
available
1.2.9.3 Critical appraisal: testing evidence for validity,
clinical relevance, and applicability
1.2.9.4 Making a decision: application of results in practice
1.2.9.5 Evaluating performance: auditing evidence-based decisions
8. Step 1: Asking focused questions: translation
of uncertainty to an answerable question
ตั้งคาถามแบบ EBM หรือ P I C O
1. ปัญหา หรือผู้ป่วย (Problem/Patient/Population) เช่น ลักษณะทาง
คลินิกของผู้ป่วย
2. สิ่งที่จะให้แก่ผู้ป่วย (Intervention) เช่น การให้ยาใหม่ หรือการใช้วิธีการ
วินิจฉัยแบบใหม่
3. สิ่งที่เป็นตัวเปรียบเทียบ (Comparison intervention) เช่น การให้
placebo หรือให้ยาเดิม
4. ผลที่ต้องการ (Outcomes) เช่น ประสิทธิผลที่เกิดขึ้น หรือความแตกต่าง
ที่ต้องการ
9. Asking a Good Question: PICO
http://www.cebm.net/asking-focused-questions/
11. Step 2: Finding the evidence: systematic
retrieval of best evidence available
Primary Sources
PubMed (www.pubmed.gov)
Ovid (ผ่านเว็บไซต์ห้องสมุด)
12. Step 2: Finding the evidence: systematic
retrieval of best evidence available
Secondary Sources (e.g. guidelines)
UK: The National Institute for Health and Care Excellence (NICE)
www.nice.org.uk
Scottish Intercollegiate Guidelines Network (SIGN) www.sign.ac.uk
US National Guideline Clearinghouse www.guideline.gov
New Zealand Guidelines Group www.health.govt.nz/about-ministry/ministry-
health-websites/new-zealand-guidelines-group
Evidence-based summaries: Bandolier www.medicine.ox.ac.uk/bandolier
BMJ Clinical Evidence clinicalevidence.bmj.com UpToDate www.uptodate.com
Systematic Reviews: Cochrane Library www.cochranelibrary.com
To search multiple databases simultaneously, use www.tripdatabase.com
19. Step 3: Critical appraisal: testing evidence for
validity, clinical relevance, and applicability
Validity (Are the results valid?)
Importance (Are the results important?)
Applicability (Will the results help me in this
patient’s care?)
20. Step 3: Critical appraisal: testing evidence for
validity, clinical relevance, and applicability
Validity
Are the results valid?
การศึกษามีความถูกต้องหรือไม่
ถูกต้องตามระเบียบวิธีวิจัยหรือไม่ ปราศจากอคติ
Study design
Data collection
Analysis methods
21. Step 3: Critical appraisal: testing evidence for
validity, clinical relevance, and applicability
Importance
Are the results important?
ผลการศึกษามีความสาคัญ (importance) หรือไม่
Effect size (ขนาด/magnitude/strength of effect)
Precision (ความแม่นยา) (Confidence intervals)
Statistical significance
Clinical significance
22. Step 3: Critical appraisal: testing evidence for
validity, clinical relevance, and applicability
Applicability
Will the results help me in this patient’s care?
นาไปใช้ในผู้ป่วยของเรา (applicability) ได้หรือไม่
Patient similarity
Patient preferences
Benefits vs. harms
Available resources
24. Step 4: Making a decision: application of
results in practice
http://med.fsu.edu/index.cfm?page=medicalinformatics.ebmTutorial
http://community.cochrane.org/about-us/evidence-based-health-care
25. Step 5: Evaluating performance: auditing
evidence-based decisions
You might consider one of the following:
Read an evidence-based abstraction journal
Keep a log book of your own clinical questions
Running a case-based discussion journal club
around questions you have recorded and selected
http://www.cebm.net/evaluating-performance/
26. Step 5: Evaluating performance: auditing
evidence-based decisions
One of the key components of evidence based
practice is reflecting on how you learn and how you
keep up to date and in addition, how much time you
spend on each process.
Activities usually identified by clinicians include:
attending lecture and conferences, reading journals,
tutorials, textbooks and guidelines, clinical practice,
small group learning, study groups, electronic
resources, and speaking to colleagues and specialists.
http://www.cebm.net/evaluating-performance/
44. Cox Regression
Bewick, Cheek & Ball (2004)
The P values indicate that the difference between treatments was bordering
on statistical significance, whereas there was strong evidence that age was
associated with length of survival.
The coefficient for treatment, –1.887, is the logarithm of the hazard ratio for a
patient given treatment 1 compared with a patient given treatment 2 of the
same age. The exponential (antilog) of this value is 0.152, indicating that a
person receiving treatment 1 is 0.152 times as likely to die at any time as a
patient receiving treatment 2
That is, the risk associated with treatment 1 appears to be much lower.
However, the confidence interval contains 1, indicating that there may be no
difference in risk associated with the two treatments.
45. Cox Regression
Bewick, Cheek & Ball (2004)
Using the Kaplan–Meier (log rank) test, the P value for the difference between
treatments was 0.032, whereas using Cox’s regression, and including age as an
explanatory variable, the corresponding P value was 0.052.
This is not a substantial change and still suggests that a difference between
treatments is likely. In this case age is clearly an important explanatory
variable and should be included in the analysis.
The exponential of the coefficient for age, 1.247, indicates that a patient 1
year older than another patient, both being given the same treatment, has an
increased risk for dying, by a factor of 1.247. Note that, in this case, the
confidence interval does not contain 1, indicating the statistical significance of
age.
46. Assumptions for Cox Regression
1. Censoring is unrelated to prognosis
2. Proportional hazards model: hazard at time t
for a patient in one group is proportional to the
hazard at time t for a patient in the second
group
47. Prognosis Checklist for Validity
Was a defined, representative sample of patients
assembled at a common (usually early) point in the course
of their disease?
Was patient follow-up sufficiently long and complete?
Were outcome criteria objective and unbiased (e.g. applied
in a ‘blind’ fashion)?
If subgroups with different prognoses are identified, did
adjustment for important prognostic factors take place?
48. Prognosis Checklist for Results
What are the results?
How likely are the outcome events over time?
Survival curves (Kaplan-Meier)
How precise are the prognostic estimates?
Confidence intervals
49. Prognosis Checklist for Applicability
Can I apply this valid, important evidence about prognosis
to my patient?
Is my patient so different to those in the study that the
results cannot apply?
Will results lead directly to selecting or avoiding a
treatment?
Will this evidence make a clinically important impact on
my conclusions about what to offer to tell my patients
52. Prognosis Example
P: In elderly men with liver cirrhosis,
I: does smoking cessation and alcohol abstinence
C: compared to do nothing
O: improve survival (live longer)?
53. Prognosis Example
พิมพ์ search terms ใน PubMed Clinical Queries ดังนี้
5-year survival cirrhosis alcohol smoking
เลือก Category: Prognosis พบ 5 บทความ
เลือกบทความของ Pessione et al: Five-year survival predictive factors
in patients with excessive alcohol intake and cirrhosis. Effect of
alcoholic hepatitis, smoking and abstinence. Liver Int. 2003
Feb;23(1):45-53.