Evidence Based Medicine
Dr. Mansour AlZahrani
SB-FM,ABFM,MRCGP[INT]
Assistant professor of Family Medicine
Head of Family Medicine Department
Definition
Evidence-based medicine requires the
integration of the best research evidence with
our clinical expertise and our patient’s unique
values and circumstances.
Patient
Values
Straus SE, Richardson WS, Glasziou P,
Haynes RB. Evidence-based medicine: how
to practice and teach EBM 3d ed. London:
Churchill Livingstone, 2005
EBM
Best
research
evidence
Clinical
Expertise
STEPS IN EVIDENCE BASED RESEARCH
1.
2.
Asking answerable questions
Finding the best evidence
3.
4.
5.
Critically appraising the evidence
Applying a decision
Evaluation
Heneghan C, Badenoch D. Evidence-based medicine toolkit. 2d ed. Malden, MA:
Blackwell, 2007
The Answerable Question
STEP 1
• Asking answerable questions – focused,
searchable, clinical
• PICO
• Patient, Problem, Population (subjects)
• Intervention or therapy – may include coalitionbuilding and/or collaborative programs (study groups)
• Comparison, Control, Context (study groups)
• Outcome (results)
Asking the Precise Question
• Background questions
• Basic aspect of a disease
• Pathophysiology
• Etiology
• Basic treatment
• Who, what, when, how
• Foreground questions
• Specific knowledge
• Have 4 parts:
•Patient/problem
•Intervention
•Comparison
intervention
•Clinical outcomes
Background or Foreground?
• Is prednisone helpful in asthma?
• What are the newest medication for asthma?
• Does ventolin used acutely make you feel
better?
• What is asthma?
Background or Foreground?
• What is asthma? (B)
• What are the newest medication for asthma? (B)
• Does atrovent used acutely make you feel better? (F)
• Is prednisone helpful in asthma? (F or B)
• Foreground if compare to other drugs
• Background if interested in how it works
Can You Identify PICO?
• In children under 6 months, how does
sleeping on back compared to sleeping on
the stomach in terms of risk of SIDS?
• In children under 6 months (P), how does
sleeping on back (I) compared to sleeping on
the stomach (C) in terms of risk of SIDS (O)?
Can You Form a PICO Question?
Clinical scenario:
5 yo with moderate persistent
asthma now in severe acute asthma
exacerbation. Intern gave 2x ventolin
and pulmicort with good
improvement. Intern asks how good
is pulmicort for prevent
hospitalization?
STEP 2
• Finding the best evidence with which to
answer the question through structured searches and
understanding the literature
• Primary Studies
• Clinical trials
• Randomized Controlled Trials
• Multicenter studies
• Secondary (synthesized, summarized) Studies
• Reviews
• Meta-analyses
MEDLINE
• The world’s largest biomedical database
• Over 5,000 journals indexed, with worldwide coverage
• Covers all aspects of biosciences and healthcare
• Database of 16+ million journal citations, 1950 to the
present
• 90% are in English ; 79% have abstracts
• The primary component of PubMed
So What Is PubMed?
• PubMed is a tool to search:
• MEDLINE (1950 to present)
• Produced by NCBI
• National Center for Biotechnology Information, part of NLM
• Accessible worldwide on the Web at no charge
Accessing PubMed
• Directly at: http://pubmed.gov
• Or, National Library of Medicine’s homepage:
http://www.nlm.nih.gov
PubMed Screen Layout
Query Box aka
Search Box
Feature Tabs
Blue
Sidebar
Searching PubMed
• Let’s use this search:
What’s the evidence for the use of beta blockers to prevent
atrial fibrillation after bypass surgery
Enter Your Search in Query Box
Results Screen
The Details Tab
Details Tab
tells you how
PubMed has
translated your
search
When to Limit?
• There are many reasons for refining a search strategy. You may
want to:
• Exclude foreign language titles
• Look for articles published within a certain timeframe
• Retrieve articles that focus on specific populations
• Look only at clinical research studies
The Limits Tab
Other Ways To Limit Your Search
• Add additional terms to query box
• Use Boolean Connectors
• AND, OR, NOT
stress AND depression
depression OR sadness OR unhappy
depression NOT manic
Working with Results
• The Display bar is used with the following pull-down menus:
• Summary lets you select other formats, such as Abstract, Brief or
Citation format
• Show and Sort By offer additional display options
• Send to lets you print, save, e-mail, order documents or the Clipboard
(a temporary holding bin)
What Are Those Icons?
• This PubMed feature allows you to:
•
•
•
•
Save search strategies and set-up automatic email updates
Save bibliographies
Select filters that customize and sort your search results
and more…
Saved Searches
My NCBI box lets you Sign in or for first time users,
Register. After a search is run, click on the Save
Search link to save the search strategy.
Saved Searches
After you sign in, the Save Search box
displays.
1) Enter a name for your search (something
meaningful),
2) click Yes or No for automatic e-mail updates and
3) click OK after you have made your selections.
More tutorial please see
http://www.youtube.com/watch?v=5ND-00Id_CI
STUDIES, STUDIES, STUDIES
STUDIES
Research
Research Design
Analytical
Descriptive
Correlational
Observational
Qualitative Study
Interview
Cohort
Case Studies/Reports
Case-Control
Cross Sectional
Experimental
Randomized
Clinical Trial
Non-Randomized
Clinical Trial
Community Trial
Cambron JA. Study Design. Lombard: National University of Health Sciences; 2008.
Good questions are the
backbone of practicing
EBM. It takes practice to
ask the well-formulated
question.
The nature of the question
asked is critically
experience dependent.
SPECIFIC KNOWLEDGE
TYPE OF
QUESTION
GENERAL KNOWLEDGE
CLINICAL EXPERIENCE
LEVELS OF EVIDENCE
Kramer BS. Weighing scientific evidence. Washington DC: National Academies
Press; 2009
STEP 3
• Critically appraising the evidence for its
validity (closeness to the truth), impact (size of
the effect) and applicability (usefulness in
clinical practice)
• Is it valid?
• Is it important?
• Can it help?
STEP 4
• Applying a decision - Combining findings to
make a recommendation, placing the evidence
into context, incorporating recommendation into
a specific patient situation, clinical setting or
organization
• How much will it help a patient or
population?
• Does it meet their values and goals?
• Is it cost-effective?
STEP 5
• Evaluation - Determining and measuring the
effectiveness of the practice change over time
• How could it be done better next time?
• What is the outcome of using (or not using)
particular information and its impact on
clinical practice?