EVIDENCE BASED MEDICINE

1. EVIDENCE-BASED
MEDICINE
(SHEGAYE Y.)
FEBRUARY 2021

2. Outline
• Introduction
• What is EBM?
• Five Steps of EBM
• EBM-Oriented physicians
• Categories of levels of evidence
• Categories of recommendations

3. Introduction
• EBM originated in the 2nd half of 19th century.
• The founder of EBM is considered to be
English epidemiologist Archie Cochrane in 19th
century.
• The term EBM was 1st used in 1990 by David
Eddy.

4. What is EBM?
EBM is a movement which aims to increase
the use of best available, high quality clinical
research in clinical decision making.
EBM is a systematic approach to clinical
problem solving which allows integration of
clinical experience (clinical expertise) and
patient values with the best available research
information.

5.  EBM is the conscientious, explicit, judicious and
reasonable use of modern(current) best evidence in
making decisions about the care of individual
patients.
• Conscientious- being careful, and thorough in
what you do.
• Explicit- being “up-front”, open, clear and
transparent.
• Judicious- using good judgment and common
sense.
• Current best evidence- “up-to-date” evidence (do
not mean perfect evidence)

6. • EBM includes three key components:
1. Research-based evidence
2. Clinical expertise (i.e. the clinician’s
accumulated experience, knowledge, and
clinical skills).
3. The patient’s values and preferences
NB. EBM encourages a dialogue between
patients and providers. Together, patients and
provider can determine an appropriate course of
action.

7. o EBM helps:
To improve quality
To improve patient satisfaction
To reduce costs
It helps physicians to provide more rational
care with better outcomes.

8. Values of EBM
#1. Help clinicians “stay current” on
standardized, evidence-based protocols.
#2. Uses near real-time data to make care
decisions.
#3. improves transparency, accountability, and
value.
#4. improve quality of care
#5. improves outcomes.

9. Five Steps Model Of EBM
1. Problem identification (formulating clinical question).
PICO format (kind of problem, intervention,
comparison of outcome). Questions about (etiology,
risk factors, frequency, diagnosis, intervention,
prognosis, cost-effectiveness, phenomena).
2. Search for wanted sources of information.
3. Critical evaluation of the information. Assessing the
quality of evidence
4. Application of information of the patient. Patient and
doctor jointly make an informed treatment decision.
5. Efficacy evaluation of this application on a patient.
Assess if the intended outcome is achieved

10. • Five steps of EBM:
1. Ask a clinical question.
2. Acquire the best up-to-date evidence.
3. Appraise (make sure it is applicable to the
population in question) the evidence.
4. Apply the evidence.
5. Assess your performance.

11. EBM-Oriented Physicians
 Five tasks of EBM-oriented physicians:
Develop efficient literature searching skills
Evaluate clinical literature based on “formal
rules” of evidence.
Use evidence summaries in clinical practice.
Develop, update evidence-based guidelines and
systematic review in their areas of expertise.
Enroll patients in studies of treatment, diagnosis
and prognosis on which medical practice is based.

12. Designing evidence-based Guideline:
 Formulate the questions
 Search the literature that can answer the questions.
 Interpret each literature to determine precisely what it says about
the questions.
 Synthesize results (meta-analysis), summarize the evidences in
“evidence table.”
 Compare the benefits, harms, and costs in a “balance sheet.”
 Draw a conclusion about the preferred practice.
 Write guideline and the rational for the guideline.
 Admit others to review each of the previous steps.
 Implement the guideline.

13. Classification of Evidence
 EBM categorizes different types of clinical evidence and
rank them according to the strength of their freedom from
the various BIASES that beset medical research.
 1a. Evidence obtained by meta-analysis of several
randomized controlled research (RCR).
 1b. Evidence from only one RCR.
 2a. Evidence from well-designed controlled research RCR.
 2b. Evidences from one quasi experimental research.
 3. Evidences from non-experimental studies(comparative
research, case study), according to some for example
textbooks.
 4. Evidences from experts and clinical practice

14. • Levels(quality) of Evidence:
1st (top): meta-analysis
2nd: randomized control trials
3rd: cohort studies
4th: case control studies
5th: case series and case reports
6th(low): editorials and expert opinions

15. • Level I
Evidence in level I is considered the gold
standard of medical knowledge because it
comes from RCTs.

16. • Level II
Level II evidence comes from three different
sources:
II-1: Evidence obtained from well designed
controlled trials without randomization.
II-2: Evidence obtained from well-designed
cohort or case-control analytic studies.
II-3: Evidence obtained from multiple time series
studies with/without the intervention.

17. • Level III
Evidence in level III is based on expert opinion,
opinions of respected authorities (ideally using
consensus methods) . Reports of expert
committees.

18. • Level IV
Evidence in level IV is based on personal
experience.
“in my experience…”

19. Factors affecting level of evidence
• RCTs have low risk of bias & the quality of
evidence is high.
• Observational studies have high risk of bias &
the quality of evidence is low.

20. Categories Of Recommendations
• Level A: Good scientific evidence suggests the
benefits substantially outweigh the risk.
• Level B: Fair scientific evidence suggests the
benefits outweigh the risk.
• Level C: Fair scientific evidence suggests a
balanced risk-benefit ratio.
• Level D: Fair scientific evidence suggests the risk
outweigh the benefit.
• Level I: Lack of scientific evidence, or poor
quality, or conflicting, such that the risk versus
benefit balance cannot be assessed.

21. Tools Used In EBM
 Statistical measures
• Likelihood ratio
• Number needed to treat/harm (NNT, NNH)
• AUC-ROC

22. References
• www.wikipedia.org/evidence-based-medicine
• www.healthcatalyst.com/evidence-based-
medicine