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Introduction to 
Evidence-based Medicine
Lara Kahale, RN, PhD
November 3, 2022
Outline
1. Define Evidence-Based Medicine (EBM) and understand its importance in clinical practice
2. Describe the steps in EBM process
3. Differentiate between the two major types of clinical questions (background vs foreground)
4. Formulate a well-built clinical question using the PICO acronym
Gaelle Chalhoub
Outline
1. Define Evidence-Based Medicine (EBM) and understand its importance in clinical practice
2. Describe the steps in EBM process
3. Differentiate between the two major types of clinical questions (background vs foreground)
4. Formulate a well-built clinical question using the PICO acronym
Evidence-based Medicine
• Conscientious, explicit, judicious, and reasonable use of current, best evidence in making 
decisions about the care of individual patients. 
Archie Cochrane, 1988 Gordon Guyatt, 1991David Sacket, 1996
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Definitions
• Evidence-based medicine (EBM)
• integrates the best research evidence with clinical expertise and individual patients' values and 
circumstances
• Evidence-based health care (EBHC)
• Extends the principles of EBM to groups or populations of patients
• Evidence-based practice (EBP)
• Extends principles of using evidence in decision-making beyond (but still including) healthcare
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Definition of EBM
Group work
What is the best research evidence?
Think, pair, share
• A patient comes to you with diabetes type II, a deficiency in insulin and excess of glucose in 
the blood. 
• Potential available treatments include:
➢ Medications: metformin (decreases glucose release into blood), glipizide (increases pancreatic 
insulin secretion), pioglitazone (increases glucose uptake from blood).
➢ Insulin therapy: short-acting injections, long-acting injections, pump
➢ Behavioral interventions: diet, exercise
• The molecular and physiological aspects of these treatments have been well-characterized, 
however, not all these treatments are equally beneficial for all patients.
➢ The physician needs to determine a course of action.
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What is the best research evidence?
Think, pair, share
How would you choose the best 
way to help this patient?
If yes, what are the strengths of 
that source; if no what are the 
limitations of that source?
Anecdote
‘Last time I gave metformin, it worked 
just fine’
Expert opinion
‘My mentor always said to give 
glipizide’
Headline on news or social media
‘I saw a paper that said pioglitazone 
worked well—though I’m not aware of 
further details’
Pathophysiological reasoning
‘It reasons that the patient would only 
need insulin after meals, as that is when 
blood sugars will be highest’
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Historical examples of pathophysiological reasoning contradicted by clinical 
research
For decades, physicians prescribed long-term hormone replacement therapy (HRT) for post-
menopausal women to reduce their risk of cardiovascular disease.
➢Although much basic science research relating estrogen pathways and cardiovascular 
physiology supported this practice, it was discontinued in the early 2000s after the 
landmark Women’s Health Initiative clinical trial found an increased risk of cardiovascular 
disease and certain cancers among women using HRT.
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Historical examples of pathophysiological reasoning contradicted by clinical 
research
Many pediatricians long supported targeting low blood oxygen saturation levels (~85%) for 
critically ill infants on ventilators to reduce the risk of retinal damage.
➢ Although basic science demonstrated the relationship between high oxygen saturation 
levels and retinal damage, results from the SUPPORT trial published in 2010 found that 
many more infants died at lower oxygen levels than at higher ones—a much more serious 
outcome than retinal damage
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What is the best research evidence?
• What is research?
• What is evidence?
• What is best?
Hypothetical clinical scenario
• A surgeon has been taught to do a procedure in a particular way A and then his bright 
colleague said I’m going to do this another way B. They start doing the procedure following 
way B, and they felt like the outcomes are better.
⎯Surgeons: Oh, I think the outcomes are better when I do it way B.
⎯You: well, how do you know that?
⎯Surgeons: Well, I did it the way A 100 times and it was not that successful, and now I did it 
way B and my impression is that it's working better.
Is there a problem? Justify your answer
• Are relying on their memory
• May be biased, it was their new idea of way B that may have their impression
• May be there were other changes that were going on that caused the outcomes to be better, 
and it has nothing to do with their new idea of way B
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⎯Surgeons: Well, I documented the outcomes very carefully in the 100 people I did it the old 
way A, and then 100 people I did it the new way B and look, here's my documentation.
⎯You: Great that you've improved things, now you're not relying solely on your memory of 
what happens; you have careful documentation.
What is a potential solution to make it more trustworthy?
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Is there a problem? Justify your answer
• May still have biases in the way the assessment was made
• Patients could have been different before and after
• Other things could have been going on, other changes in care 
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⎯Surgeons: we could do an observational study, where, in parallel, we apply way A on a group 
of patients and way B on another group of patients. Different surgeons stand more 
standardized assessments, documentation of co-intervention, other things that are done, and 
now it becomes more trustworthy.
⎯You: But the patients might have been different in the two groups.
What is a potential solution to make it more trustworthy?
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⎯Surgeons: let's now randomize them so the baseline characteristics are similar
⎯You: Ok great. Well, wait a minute, there still could be bias in the outcome assessment- let's 
not only randomize people, let's make the outcome assessment blind.
What is a potential solution to make it more trustworthy?
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What did we do?
We went from a systematic observation to the most sophisticated research design, by ??? 
Reducing bias
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What is the best research evidence?
• What is research?
• What is evidence?
• What is best?
Definition of EBM
What is clinical expertise?
• The ability to use our clinical skills and past experience to rapidly identify each patient’s 
unique health state and diagnosis, their individual risks and benefits of potential 
interventions.
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What is clinical expertise?
PLEASE, as tempting as it might be, DO NOT take what a 
physician says for granted
‘Prove all things; hold fast that which is good, abstain from all appearance of evil.’ 
1 Thessalonians 5: 21-22
What are patients' values?
• The unique preferences, concerns and expectations each patient brings to a clinical 
encounter
• Knowledge about costs of andaccess to treatments (e.g., does the hospital formulary contain 
the drug? Will insurance pay for it?)
• Ethical and legal knowledge of the patient’s rights and a physician’s duties
• Engaging patients in deciding upon their own health includes reading, understanding, and 
acting on health information, working together with clinicians to evaluate and select the right 
treatment options and providing feedback on outcomes.
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Outline
1. Define Evidence-Based Medicine (EBM) and understand its importance in clinical practice
2. Describe the steps in EBM process
3. Differentiate between the two major types of clinical questions (background vs foreground)
4. Formulate a well-built clinical question using the PICO acronym
Ask
Acquire
Appraise
Apply
Patient 
Dilemma
Essential Steps 
of EBM
Assess
MED 2
Outline
1. Define Evidence-Based Medicine (EBM) and understand its importance in clinical practice
2. Describe the steps in EBM process
3. Differentiate between the two major types of clinical questions (background vs foreground)
4. Formulate a well-built clinical question using the PICO acronym
Background and Foreground Questions
• Background questions: broad, answers are well-established and commonplace.
➢ e.g., “What is tuberculosis?” or “What is amniocentesis?”
• Foreground questions: pertain to a specific patient or problem.
➢ e.g., “Which is a more effective treatment for diabetes type II for a middle-aged woman 
with no other health issues—metformin or behavior modification alone?”
Why is it important to classify a question as background vs foreground?
• To help determine the best place or resource to look for an answer to that question
• Background questions are best investigated in secondary literature—that is, synthesized or 
summarized literature.
➢ Example of secondary literature: textbooks.
• Foreground questions may be investigated in both secondary and primary literature—that is 
unfiltered original research.
➢ Example of primary literature: studies published in medical journals. 
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Sub-types of foreground questions
• Intervention (treatment or prevention)
➢ e.g., “Does use of a daily baby aspirin reduce the risk of heart attack in 
middle-aged men?”
• Diagnosis
➢ e.g., "What is the likelihood that a positive immunoassay result for HIV 
is false?”
• Prognosis
➢ e.g., "What is the long-term risk of recurrence after remission of 
invasive ductal carcinoma after partial mastectomy?”
➢ Etiology/Harm/Risk
➢ e.g., "Does consumption of diet soda during pregnancy increase the risk 
of birth defects?”
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Outline
1. Define Evidence-Based Medicine (EBM) and understand its importance in clinical practice
2. Describe the steps in EBM process
3. Differentiate between the two major types of clinical questions (background vs foreground)
4. Formulate a well-built clinical question using the PICO acronym
What is PICO?
• Acronym for the main parts of a clinical question, it stands for:
➢ P – Patient (e.g., age, gender, disease)
➢ I – Intervention (e.g., a surgery or medication)
➢ C – Comparison (e.g., placebo or other treatment)
➢ O – Outcome (e.g., death or years of remission)
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Variations of PICO
• PICO is the general term used for formulating questions especially those related to 
interventions (treatment or prevention). 
• For diagnosis questions: PTSD
➢ P – Patient
➢ T – Test
➢ S – Standard (e.g., you might compare a “new” to conventional test)
➢ D – Disease
• For prognosis questions: PFO
➢ P – Patient
➢ F – Factors (e.g., qualifiers of patient’s condition, like “post-radiation therapy”)
➢ O – Outcome (e.g., years in remission)
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Group work
Formulate PICO question
think, pair, share
• A 44-year-old woman comes into your office. She has previously been diagnosed with clinical 
depression. The woman calmly explains to you that she will not be taking any “drugs” as this 
conflicts with her beliefs. She wants to know if St. John’s Wort is as effective as traditional 
antidepressants for treating her symptoms
• P:
• I:
• C:
• O:
Formulate PICO question
think, pair, share
• A 44-year-old woman comes into your office. She has previously been diagnosed with clinical 
depression. The woman calmly explains to you that she will not be taking any “drugs” as this 
conflicts with her beliefs. She wants to know if St. John’s Wort is as effective as traditional 
antidepressants for treating her symptoms.
• P: middle-aged, female, clinical depression
• I: St. John’s Wort
• C: Antidepressant treatment
• O: reduction of depressive symptoms
Plain language 
• Note: You should always be able to restate your PICO as a plain language question.
➢ e.g., “For a middle-aged female with clinical depression, is St. John’s Wort as effective as 
antidepressants to reduce depressive symptoms?”
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T: +961 1 577055 
Youssef Sursock Street – Rmeil, Beirut
P.O. BOX: 16-5146 – Ashrafieh, Lebanon
Email: info@sgub.edu.lb
www.sgub.edu.lb
Questions?