This document discusses the principles of evidence-based medicine (EBM), highlighting its definition, hierarchy of evidence, and the significance of integrating clinical research with physician experience and patient preferences. It covers various types of clinical questions, evidence sources, and the process of utilizing medical literature for optimal patient care, including practical examples and guidelines for searching. The importance of systematic reviews, particularly through organizations like the Cochrane Collaboration, is emphasized for making informed health interventions.

1. Evidence Based Medicine
Noha Salah Baghdady, M. Sc.

2. Learning Objectives
• Clinical Questions types .
• A Hierarchy of Preprocessed Evidence.
• EBM definition and value.
• Knowledge and Skills Necessary for Optimal
Evidence-Based Practice.
• Basic computer and internet knowledge for
electronic searching of the literature

3. Case Study
• A 30-year-old female presents with recurrent
Urinary tract infection for past 8 months;
these episodes have been treated with several
courses of antibiotics but keep recurring. She
asks if recurrences can be prevented with
antibiotics.

4. History
1980
• The researchers found that physicians were
using very different standards to decide which
patients required surgery.
• The variation rates of prostate surgery &
hysterectomy of up to 300% between similar
countries.

5. Definition
Evidence based medicine could be defined as
the science of integrating the best available
evidence from clinical research with physicians
experience and patients' unique values and
preferences.
(David Sackett and colleagues)

6. EBM Triads

7. Gordon Guyatt and colleagues from
McMaster University (Canada) in 1992

8. The clinical question
background vs. foreground
1- Background questions:
• Their answers are “fiber of medicine.”
• Answers usually found in medical textbooks.

9. The clinical question
background vs. foreground
2- Foreground questions
• are those usually found at the cutting edge of
medicine.
• They are questions about the most recent
therapies, diagnostic tests, or current theories
of illness causation.
• These are the questions that are the heart of
the practice of EBM.

10. Novice Expert
Background
Question
Foreground
Question

11. Examples
• Background questions:
1- The causative microbiologic agent of disease.
2- A recommended dose of a drug.
3- A list of the attributes of syndrome.
• Foreground questions:
1- Intervention or exposure
2- A possible comparison intervention
3- Outcomes of interest.

12. The Traditional Method of Medical
Practice
1. Knowledge
2. Reading
3. Experience
4. Experts and peers opinions

13. Using the Medical Literature to
Provide Optimal Patient Care
Using the Medical Literature to Provide Optimal Patient Care
Identify your problem.
↓
Define a structured question.
↓
Find the best evidence.
(original primary study or evidence summary)
↓
How valid is the evidence?
↓
What are the results?
↓
How should I apply the results to patient care?

14. How to Practice
1- Asking clinical
questions.
2- basic knowledge
for electronic
searching of the
literature.
3- application of
critical appraisal
rules.

15. Scheme
Question (Diagnosis- treatment - Harm -
prognosis question)
PICO
Search Terms
Search Strategy
Conclusion & References

16. 1- Asking

18. Examples
• A 30-year-old female presents with recurrent
Urinary tract infection for past 8 months; these
episodes have been treated with several courses
of antibiotics but keep recurring. She asks if
recurrences can be prevented using antibiotics.
• P = Female patient with recurrent UTI.
• I = prophylactic AB.
• C = No intervention.
• O = No recurrence.

19. Examples
• What is the duration of recovery for patients
with total hip replacement who developed a
post-operative infection as opposed to those
who did not within the first six weeks of
recovery ?

20. PICO
• Patient: patients with total hip replacement.
• Intervention: developed a post-operative
infection.
• Comparison: opposed to those who did not.
• Outcome: the duration of recovery.

21. Examples
Jean is a 55 year Old woman who quite often
crosses the Atlantic to visit her elderly mother.
She tends to get swollen legs on these flights
and is worried about her risk of developing deep
vein thrombosis (DVT), because she read quite a
bit about this in the newspapers lately. She asks
you if she would wear elastic stocking on her
next trip to reduce her risk of this.

22. PICO
• P= 55 years Old woman.
• I= elastic stocking.
• C= no intervention.
• O= prevention DVT risk in long trips.

23. Basic computer and internet knowledge for
electronic searching of the literature

24. A Hierarchy of Preprocessed Evidence

25. The Haynes 5S, knowledge acquisition pyramid.

26. 1. Studies
• Selecting only those studies that are both highly
relevant and characterized by study designs that
minimize bias and thus permit a high strength of
inference.
• Original or primary studies (eg, those stored in
MEDLINE).
• Many studies exist but the information they contain
needs evaluation before application to clinical
problems.

27. 2. Systematic reviews (syntheses)
• Reviews involving the identification, selection, appraisal, and
summary of primary studies addressing a focused clinical question
using methods to reduce the likelihood of bias.
• The Cochrane Collaboration provides systematic reviews of health
care interventions. You can also find systematic reviews in MEDLINE
and other databases.
• By collecting the evidence on a topic, systematic reviews become
more useful than individual or primary studies.

28. Systematic review VS meta-analysis

29. 3. Synopses
• Brief summaries that encapsulate the key methodologic
details and results of a single study or systematic review.
• Pre appraised resource journals and products such as ACP
Journal Club.
1- Initially, the articles act as an alerting service to keep
physicians current on recent advances.
2- When rigorously and systematically assembled, the content of
such resources becomes, over time, a database of important
articles.

32. 4. Summaries & Systems
• Practice guidelines, clinical pathways, or evidence-based
textbook summaries that integrate evidence-based
information about specific clinical problems and provide
regular updates to guide the care of individual patients.

33. Extract “Key Words”

34. Boolean operators
“AND” “OR’’ “NOT’’

35. Boolean operators
• The basic Boolean logic operators for
searching are: AND, OR and NOT
• These operators can be used to narrow or
broaden searches

36. “AND’’
A B• narrow or broaden
searches ??

37. ‘’OR’’
A B
• narrow or broaden
searches ??

38. ‘’NOT’’
A B• narrow or broaden
searches ??

39. Try Boolean operators

40. Evidence Based Guidelines

41. National Guideline Clearinghouse
• A database of evidence-based clinical practice guidelines and
related documents. It is maintained as a public resource by
the Agency for Healthcare Research and Quality (AHRQ) of the
U.S. Department of Health and Human Services.
• The database is updated weekly with new and revised
guidelines. The currency of all guidelines is verified annually
through NGC's Annual Verification process.

42. National Guideline
Clearinghouse
The site features:
• A Guideline Comparison utility that gives users the ability
to generate side-by-side comparisons.
• Guideline Syntheses prepared by NGC staff, comparing
guidelines covering similar topics, highlighting areas of
similarity and difference.
• An electronic forum, NGC-L for exchanging information on
clinical practice guidelines, their development,
implementation and use
• An Annotated Bibliography database where users can
search for citations for publications and resources about
guidelines, including guideline development and
methodology, structure, evaluation, and implementation.

43. Clinical practice guidelines
illustrate that this classification (like any other)
has its limitations: guidelines have aspects of
systems and summaries, and sometimes of
synopses.

45. National Guideline Clearinghouse
Use:
• Quotation marks “ “
• Boolean operators (AND, OR, NOT)
• Asterisk (*)

46. Scenario
• A 30-year-old female presents with recurrent
Urinary tract infection for past 8 months;
these episodes have been treated with several
courses of antibiotics but keep recurring. She
asks if recurrences can be prevented.

51. Scenario
• 25 years old male
complaining from Chronic
obstructive pulmonary
disease (COPD) and the
case was worsen last
week, the patient visited
the clinic for finding the
best treatment modality.

57. Systematic Reviews

60. Cochrane Collaboration
• The Cochrane Collaboration is an independent nonprofit
organization consisting of a group of more than 31,000
volunteers in more than 120 countries.
• The collaboration was formed to organize medical research
information in a systematic way to facilitate the choices that
health professionals, patients, policy makers and others face
in health interventions according to the principles
of evidence-based medicine.

61. Cochrane Collaboration
• The Cochrane Collaboration
was founded in 1993 under
the leadership of Iain
Chalmers.
• It was developed in
response to Archie
Cochrane's call for up-to-
date, systematic reviews of
all relevant randomized
controlled trials of health
care.

62. THE COCHRANE LIBRARY
• Relies only on high quality randomized
controlled trials for generating its evidence.
• Contains systematic reviews.
http://www.cochrane.org
http://www.thecochranelibrary.com

63. THE COCHRANE LIBRARY
Database of Systematic Reviews Covers broad
range of disciplines.

81. Authors' conclusions
• Continuous antibiotic prophylaxis for 6-12 months
reduced the rate of UTI during prophylaxis when
compared to placebo.
• After prophylaxis two studies showed no difference
between groups. There were more adverse events in
the antibiotic group.
• One RCT compared postictal versus continuous daily
ciprofloxacin and found no significant difference in
rates of UTIs, suggesting that postcoital treatment
could be offered to woman who have UTI associated
with sexual intercourse.

86. Studies

89. Cross-sectional Study

90. MEDLINE
(Indexing system)
www.pubmed.gov.

91. The Medline
• The Medline database represents the largest
resource for non-appraised evidence all over
the world.
• It contains over sixteen million abstract of
scientific publications from about 480 medical
journals in the USA, Europe and the rest of the
world.
• It covers almost 40-50% of the worlds'
scientific publications.

94. Filters

98. Send To

99. Saving

101. Clinical Queries

102. Clinical Queries

105. (Medical Subject Headings) MeSH

106. (Medical Subject Headings) MeSH
• MeSHis a list of controlled vocabulary
generated by the U.S. National Library of
Medicine
(http://www.nlm.nih.gov/mesh/2002)to index
abstracts of research papers published in the
Pubmed.
• A subject heading search is a powerful tool for
finding sets of only the most relevant records.

110. Scenario
22 years old male diagnosed with rhinosinusitis
(RS), the physician prescribed an antibiotic for
him and tolled him to come back after 10 days ..
You remembered that you read something
about the effectiveness of antibiotic treatment
for acute RS.. You go to check this !!

112. PICO

113. Answer
Q: what is the effectiveness of antibiotic
treatment for acute RS ??
P = patient with acute RS ??
I = Antibiotic
C= no antibiotic
Outcome = Cure

117. Authors’ conclusion
The potential benefit of antibiotics in the treatment of
clinically diagnosed acute rhinosinusitis needs to be seen
in the context of a high prevalence of adverse events.
Taking into account antibiotic resistance and the very low
incidence of serious complications, we conclude that
there is no place for antibiotics for the patient with
clinically diagnosed, uncomplicated acute rhinosinusitis.
This review cannot make recommendations for children,
patients with a suppressed immune system and patients
with severe disease, as these populations were not
included in the available trials.

119. Conclusion
Among patients with acute rhinosinusitis, a 10-
day course of amoxicillin compared with placebo
did not reduce symptoms at day 3 of treatment.

120. THANK YOU 