The document provides an overview of evidence-based medicine (EBM) and its five-step process. It defines EBM as the integration of best research evidence with clinical expertise and patient values. The five steps of EBM are: 1) defining the clinical problem, 2) finding evidence, 3) appraising the evidence, 4) applying to patient care, and 5) evaluating the application. Key points include using the PICO framework to build clinical questions, considering the type of evidence needed based on the question, and searching reliable sources of pre-appraised evidence like Cochrane reviews. An example shows how to apply these concepts to a patient scenario.

1. EVIDENCE-BASED MEDICINE
Tuyet T. Nguyen, MD, Ph.D
Jan 19, 2024

2. WHAT IS EVIDENCE-BASED MEDICINE?
https://www.youtube.com/watch?v=QUW0Q8tXVUc

3. LEARNING OBJECTIVES
• Define Evidenced-Based Medicine (EBM) and understand its
importance in the clinical setting
• Explain each of the five steps in the EBM process
• Create a well-built clinical question using the PICO framework
• Identify high quality resources that may assist in answering clinical
care questions

4. “The conscientious, explicit, and judicious use of current
best evidence in making decisions about the care of
individual patients.”
David Sackett et al, BMJ, 1996
EVIDENCED BASED MEDICINE (EBM)

5. EVIDENCED BASED MEDICINE
• EBM is the integration of:
• Clinical expertise
• Patient values and preferences
• Best research evidence
• Approach to medical practice
that optimizes decision-making
by emphasizing use of evidence
from well-conducted research
Patient
Values
Clinical
Expertise
Best Research
Evidence
Masic, Izet et al. Acta informatica medica, 2008

6. WHY IS EBM IMPORTANT?
“Half of what you are taught as medical students will in 10 years have
been shown to be wrong…
And the trouble is, none of our teachers know which half”
- Sydney Burwell (former dean of Harvard Medical School)

7. WHY IS EBM IMPORTANT?
• Medical knowledge and accepted
practices change rapidly
• Volume of research articles is expanding
exponentially
• Integrating evidence into practice
regularly makes it easier to find and apply
the evidence during busy clinical
schedules
• Allows physicians to blend patients’
preferences with research, resulting in
patient-centered care Data were derived from searching PubMed.gov 1946 to 2019

8. EBM FRAMEWORK
Step 1. Define problem
Step 2. Find evidence
Step 3. Appraise the evidence
Step 4. Apply to patient care
Step 5. Evaluate efficacy of EBM application on a patient

9. EBM FRAMEWORK
Step 1. Define problem
Step 2. Find evidence
Step 3. Appraise the evidence
Step 4. Apply to patient care
Step 5. Evaluate efficacy of EBM application on a patient

10. STEP 1. DEFINING PROBLEM
• Formulate clear, answerable clinical question(s)
• Utilize PICO framework
• Consider the type of question asked

11. PICO format:
• Patient or problem
• Intervention
• Comparison of interventions
• Outcome
T: Type of questions
(treatment/diagnosis
/prognosis/harm/etio
logy)
S: type of study you
want to find
STEP 1. DEFINING PROBLEM

12. CASE EXAMPLE
Minh is 45 year-old healthy male that has smoked cigarettes for the
past 20 years. He smokes 1 pack per day and has not previously
tried to quit because he claims that smoking helps him relax from
his stressful job. Recently, Minh’s grandmother was diagnosed with
stage 4 lung cancer and he is serious about quitting cigarettes.
Minh has googled that electronic cigarettes can help quit smoking
and are superior to the nicotine patch. Minh would like to discuss
this option with you.

13. CASE EXAMPLE CONT.
• PICO framework:
• Patient = middle aged adult smoker
• Intervention = electronic cigarettes
• Comparison = nicotine replacement
• Outcome = smoking cessation

14. CASE EXAMPLE CONT.
Question: In middle aged adult smokers, what is the effect
of electronic cigarettes on smoking cessation compared with
nicotine replacement?

15. CASE EXAMPLE CONT.
Question: In middle aged adult smokers, what is the effect
of electronic cigarettes on smoking cessation compared
with nicotine replacement?

16. CASE EXAMPLE CONT.
Question: In middle aged adult smokers, what is the effect
of electronic cigarettes on smoking cessation compared
with nicotine replacement?

17. CASE EXAMPLE CONT.
Question: In middle aged adult smokers, what is the effect
of electronic cigarettes on smoking cessation compared
with nicotine replacement?

18. PICO: Individual/Partner Practice
You have a four-month-old baby admitted to your ward with viral
bronchiolitis. The child’s symptoms get progressively worse, and you
wonder whether giving corticosteroids might help the child improve
and reduce the length of stay in hospital.

19. • Patient or problem: infant with viral bronchiolitis.
• Intervention: corticosteroids.
• Comparison: no corticosteroids.
• Outcomes: clinical score, length of hospital stay.
Question: In an infant with viral bronchiolitis, does the
administration of corticosteroids compared with not giving
corticosteroids improve clinical score and reduce length of hospital
stay?
PICO: Individual/Partner Practice

20. PICO: Individual/Partner Practice

21. EBM FRAMEWORK
Step 1. Define problem
Step 2. Find evidence
Step 3. Appraise the evidence
Step 4. Apply to patient care
Step 5. Evaluate efficacy of EBM application on a patient

22. Two important factors to consider:
• Type of question asked
• Best supporting evidence
• Hierarchy of evidence
• Sources
• Quality
STEP 2. FINDING THE EVIDENCE

23. TYPE OF QUESTION OF ASKED
• The type of question asked helps determine the most appropriate
type of evidence (study design) to look up:
• Diagnosis: how to select and interpret diagnostic tests
• Therapy: how to select treatments that do more good than harm
and that are worth the efforts and costs of using them
• Prognosis: how to estimate the patient’s likely clinical course
over time
• Harm/Etiology: how to identify causes for disease (including
iatrogenic forms)

24. WHAT KIND OF STUDY?
 Descriptive
o Case reports
o Case series
o Population studies
o General review articles

25. WHAT KIND OF STUDY?
 Explanatory
o Observational:
o Cohort studies
o Case-Control studies
o Cross-sectional studies
o Experimental
o Randomized controlled trial
o Randomized placebo-controlled trial
o Double-blind randomized controlled trial
o Systematic Reviews
o Meta-analysis

26. Type of questions Source of evidence
Therapy/Prevention Double blind randomized controlled trial
Systematic review of such studies
Prospective controlled trial
Etiology/Cause/Harm RCTs or systematic reviews (drug adverse events)
Retrospective case-control (other causation)
Prospective cohort studies
Case studies or case series
Diagnosis Prospective cohort studies or cross-sectional studies
systematic review; blind comparison to a gold
standard
Prognosis Cohort study or prospective cohort study, or a
systematic review
TYPE OF QUESTION AND STUDY DESIGN

27. TYPES OF EVIDENCE
o Single research studies: RCT,
observational studies
o Recent research findings
o Results may be inconsistent with
other studies
o Reader's responsibility to
appraise the study and make a
decision
o Interpretation or analysis of several
studies (primary evidence)
o Pre-appraised
o Explicit, reproducible process to
evaluate the scientific merit of its
source evidence
o Evidence summaries & systematic
reviews
Primary evidence Secondary evidence

28. HIERARCHY OF EVIDENCE
• Not all evidence is created
equal
• Risk of bias decreases as you
travel up the pyramid
• Some questions do not have
RCTs, must rely on
observational studies
• Systematic reviews and meta-
analyses often form basis of
recommendations/guidelines

29. WHERE AND WHAT TO LOOK?
Principles:
o Go for quality-filtered if possible (synthesized from explicitly
evaluated evidence, or pre-appraised for quality)
o Go for the best evidence you can
o If you find a good answer (valid, important, applicable), it’s
o.k. to stop looking

30. FOR BACKGROUND INFORMATION
 Look for evidence-based synthesized sources:
o ACP PIER
o Dynamed
o Clinical Evidence
 Look for clinical practice guidelines or clinical decision rules with
explicit levels of evidence
oNHS Clinical Knowledge summaries,
oNational Guideline Clearinghouse
oTRIP is a good route to find practice guidelines

31. FOR BACKGROUND INFORMATION
 Look for current standard clinical textbooks, paper or electronic
format, with references
o ACP Medicine
o e-Medicine
o MDConsult
o StatRef
o Access Medicine
o Books@OVID
 Look for current review articles based in research literature,
systematic reviews if possible

32. FOR FOREGROUND INFORMATION
• “Pre-appraised” sources
o Cochrane Library
o Evidence-based Medicine
o Evidence Updates
o ACP Journal Club
o Clinical Evidence
o BestBETS
• Database
o Medline
o PubMed
o EMBASE
o Web of Science,
SCOPUS

33. EBM EMAIL RESOURCES
• NEJM Journal Watch (internal medicine/medicine subspecialties)
• ACCESSSS (all disciplines)
• Uptodate (all disciplines)
• Wiki Journal Club (internal medicine and surgery)

34. NEJM JOURNAL WATCH
https://www.jwatch.org/
• Weekly or monthly updates
on internal medicine topics:
• General medicine
• Hospital medicine
• Cardiology
• Infectious diseases
• Hematology/oncology
• Neurology
• Geriatrics
• Allergy/immunology
• Rheumatology

35. NEJM JOURNAL WATCH

36. ACCESSSS
• Daily to weekly updates on any discipline (including internal medicine, pediatrics, and surgery)
https://www.accessss.org/

37. ACCESSSS

38. UPTODATE
• Biweekly updates from uptodate
• Focus on recent and important
“new” and “practice changing”
updates
• Covers 25 different disciplines

39. WIKI JOURNAL CLUB
• Collaborative website
that provides concise
summaries of
landmark clinical trials
• Summarizes and
reviews landmark
studies across
medicine and surgical
specialties
https://www.wikijournalclub.org/wiki/Main_Page

40. WIKI JOURNAL CLUB
https://www.wikijournalclub.org/wiki/Main_Page

41. WIKI JOURNAL CLUB
https://www.wikijournalclub.org/wiki/Main_Page

42. CASE EXAMPLE CONT.
• Question: In middle aged adult smokers, what is the effect of
electronic cigarettes on smoking cessation compared with nicotine
replacement?
• Sources:
• Access
• Agency for Healthcare Research and Quality (AHRQ)
• Cochrane Database of Systematic Reviews
• Turning Research Into Practice (TRIP)
• UpToDate
• US Preventative Services Task Force (USPSTF)

43. PRE-APPRAISED SYNTHESIS EXERCISE
• In groups of 4-5, please research your assigned resource and
answer the following questions.
• Question: In middle aged adult smokers, what is the effect of electronic
cigarettes on smoking cessation compared with nicotine replacement?
• Background on the resource
• Searchability (i.e., how easy and intuitive is the search function)
• Results
• What type(s) of output did the resource provide (i.e., summary, systematic reviews, primary literature,
etc)
• How helpful was the output
• Did it answer the clinical question above
• Recommendation
• How would you advise using this resource
• Would you recommend using it
• Other thoughts

44. • Grading of Recommendations Assessment, Development, and
Evaluation (GRADE)
• Developed by Greg Guyatt, McMaster University
• Method of assessing the quality of evidence and strength of
recommendations
• Provides structured and transparent framework for developing and
presenting summaries of evidence
• Classifies quality of evidence into 4 levels
BMJ. 2008 Apr; 336(7650): 924–926
RATING EVIDENCE: GRADE

45. RATING EVIDENCE: GRADE
• High quality: Further research is very unlikely to change our
confidence in the estimate of effect
• Moderate quality: Further research is likely to have an important
impact on our confidence in the estimate of effect and may change
the estimate
• Low quality: Further research is very likely to have an important
impact on our confidence in the estimate of effect and is likely to
change the estimate
• Very low quality: Any estimate of effect is very uncertain

46. • Large magnitude of effect
• Dose-response gradient
• All residual confounding would
decrease magnitude of effect
(in situations with an effect)
Certainty can be rated down Certainty can be rated up
https://bestpractice.bmj.com/info/toolkit/learn-ebm/what-is-grade/
• Risk of bias
• Imprecision
• Inconsistency
• Indirectness
• Publication bias
RATING EVIDENCE: GRADE

47. GRADE: Example

48. USPSTF: Another Example

49. EBM FRAMEWORK
Step 1. Define problem
Step 2. Find evidence
Step 3. Appraise the evidence
Step 4. Apply to patient care
Step 5. Evaluate efficacy of EBM application on a patient

50. STEP 3. APPRAISE THE EVIDENCE
Three main areas:
• Validity
• Importance
• Applicability

51. STEP 3: APPRAISE THE EVIDENCE
• Important questions to consider during this phase:
• How serious is the risk for bias
• How to interpret results in a standardized method
• Requires basic knowledge of statistics

52. RISK OF BIAS
• Bias is a systematic error, or deviation from the truth, in the
results or inferences of a study
• Common types of bias to consider:
• Selection Bias
• Allocation Bias
• Performance Bias
• Detection Bias
• Attrition Bias
• Publication Bias

53. RISK OF BIAS
• Patient randomization (i.e., computer generated randomization tables)
• Group allocation concealed
• Groups similar in prognostic factors (i.e., check table 1)
• Blinding
• Follow-up (>80% participants complete study)
• Participants analyzed in initial group (i.e., intention to treat analysis)
• Trial stopped early

54. INTERPRETING THE RESULTS
• For a therapy study, consider:
• Relative risk
• Absolute risk reduction
• Number needed to treat

55. CASE EXAMPLE CONT.

56. CASE EXAMPLE CONT.
• Adults attending UK National Health Service stop-smoking services from
2015 – 2018
• 886 participants randomized into 2 arms:
• Electronic cigarettes (“e-cigarettes”)
• Nicotine replacement products (e.g., patches, gum, lozenges, nasal spray, etc.)
• Primary outcome = sustained abstinence for 1 year (biochemically
confirmed)
• Secondary outcomes = respiratory symptoms; patient-reported treatment
usage

57. RELATIVE RISK (RR)
• Relative risk (RR) is the ratio of risk in the experimental (i.e., intervention) group
compared to risk in the control (i.e., comparison) group
• RR = 1 means that exposure does not affect outcome
• RR < 1 means that the risk of the outcome is decreased by exposure
• RR > 1 means that the risk of the outcome is increased by exposure
• Example above: e-cigarette rate / nicotine replacement rate
• 18.0% / 9.9% = 1.82

58. ABSOLUTE RISK REDUCTION (ARR)
• ARR is difference between the rates of events in the experimental
(i.e., intervention) group and control (i.e., comparison) group
• Example above: e-cigarette rate - nicotine replacement rate
• 18.0% - 9.9% = 8.1%

59. Number Needed to Treat (NNT)
• NNT is the number of patients needed to be treated to achieve one
additional therapeutic success
• NNT = 1 / Absolute risk reduction
• Example above: 1 / (e-cigarette rate - nicotine replacement rate)
• 1 / 8.1% = 12 (round to nearest whole number)

60. CASE EXAMPLE CONT.
• Question: In middle aged adult smokers, what is the effect of
electronic cigarettes on smoking cessation compared with nicotine
replacement?
• Primary outcome = sustained abstinence for 1 year
• Relative risk: 1.82
• Absolute risk reduction: 8.1%
• Number needed to treat: 12 patients

61. EBM FRAMEWORK
Step 1. Define problem
Step 2. Find evidence
Step 3. Appraise the evidence
Step 4. Apply to patient care
Step 5. Evaluate efficacy of EBM application on a patient

62. EFFECTS ON PATIENT CARE
• Consider the similarity of your patient to the study participants
(i.e., does your patient match the study inclusion criteria)
• Are all patient important outcomes considered (i.e., primary and
secondary end points)
• Consider the benefits versus harms/costs (i.e., consider NNT,
cost to patient, side effects)

63. EFFECTS ON PATIENT CARE

64. CASE EXAMPLE CONT.
• Question: In middle aged adult smokers, what is the effect of
electronic cigarettes on smoking cessation compared with nicotine
replacement?
• Statistical significance: evidence showed that e-cigarettes are
superior to nicotine replacement products and that 12 patients would
need to be treated with e-cigarettes for one additional patient to have
sustained abstinence

65. CASE EXAMPLE CONT.
• Question: In middle aged adult smokers, what is the effect of
electronic cigarettes on smoking cessation compared with nicotine
replacement?
• Statistical significance: evidence showed that e-cigarettes are
superior to nicotine replacement products and that 12 patients would
need to be treated with e-cigarettes for one additional patient to have
sustained abstinence
• Clinical significance:

66. CLINICAL SIGNIFICANCE

67. CLINICAL SIGNIFICANCE

68. CASE EXAMPLE CONCLUSION
Would you advise Minh to try electronic cigarettes instead of
nicotine replacement products to help with smoking
cessation?

69. EBM IN CLINICAL PRACTICE
Now that we have discussed the basics of evidence-based
medicine (EBM), how do you plan to incorporate EBM into
your own clinical practice?

70. REFERENCES
• Evidence Based Medicine? How to Practice and Teach EBM David L Sackett, W Scott
Richardson, William Rosenberg, R Brian Haynes Churchill Livingstone, ?14.99, pp 250 ISBN 0
443 05686 2
• Evidence-Based Medicine: A Short History of a Modern Medical Movement, Virtual
Mentor. 2013;15(1):71-76. doi: 10.1001/virtualmentor.2013.15.1.mhst1-1301
• Evidence based medicine: what it is and what it isn’t. Sackett DL, Rosenberg WM, Gray JA,
Haynes RB, Richardson WS. BMJ. 1996;312(7023):71.
• A Brief History of Evidence-Based Medicine (EBM) and the Contributions of Dr David Sackett
Achilleas Thoma & Felmont F. Eaves III ,, Aesthetic Surgery Journal, 2015

71. ASSIGNMENTS

72. ASSIGNMENT #1
• A 59-year-old man is evaluated in the emergency department for fever and
jaundice. He has decompensated alcoholic cirrhosis with ascites. Current
medications are furosemide and spironolactone.
• On physical examination, temperature is 38.1 °C, BP is 100/60 mm Hg, and
pulse rate is 60/min. Jaundice is present. Abdominal examination shows
ascites and splenomegaly.
• Laboratory evaluation shows a serum creatinine level of 1 mg/dL (88.4
μmol/L), blood urea nitrogen level of 30 mg/dL (10.7 μmol/L), and total
bilirubin level of 4.1 mg/dL (70.1 mmol/L).
• Diagnostic paracentesis for evaluation of ascitic fluid shows neutrophil
count of 350/μL (0.35 × 109/L).

73. You gave Cefotaxime for patient for his SBP. You are also wondering if
albumin is helpful for this patient. Using PICO format, formulate the
question and try to find the resource that help to answer your
question.
ASSIGNMENT #1

74. ASSIGNMENT #2
• Anh is a 32-year-old man who presented to the Emergency Department
with abdominal pain. He is diagnosed with uncomplicated acute
appendicitis on CT scan. You recommend that the patient go to the
Operating Theater for urgent appendectomy.
• The patient is nervous about having surgery because he has a family
member who had a wound infection and developed a hernia after having
their appendix removed. He is also worried about missing time at work. He
tells you that he performed an internet search for “appendicitis treatment”
and saw that some people are treated with antibiotics without surgery. He
asks if that would be a safe option for him.

75. • Using PICO format, formulate your question and find the
resource to answer your question.
ASSIGNMENT #2

76. • Due date: 5:00 PM, January 26, 2024
• Upload your assignment on Canvas – Course Research and
EBM
• Documents should include the trial/research you found to
answer your question.
ASSIGNMENT