Evidence-Based Medicine:
How to Effectively and Efficiently
Search for the Answer to your
Clinical Questions
Donna Windish, MD, MPH
Associate Professor of Medicine
What is the Importance of
Answering Clinical Questions?
• Provide evidence-based care
• Teach patients and colleagues
• Lifelong self-directed learning
Yale trainees
Knowledge
Performance
Outcomes
Time since training →
Choudhry NK, Ann Intern Med. 2005;142(4):260-273
Evidence-based practice
Acquire
(Appraise)
Ask
Best
evidence
Apply
Clinical expertise
Clinical state and
circumstances
Haynes RB, ACPJC. 2002 Mar-Apr;136:A11
Preferences
and actions
Epidemiology of clinical questions
•
•
•
•

Studies of outpatient physicians
For every 3 patients seen in the office, 2 clinical
questions were generated1,2,3
Most questions involved therapy and diagnosis
Majority of questions deemed clinically important
30% pursued, often using non-evidence-based
sources
Factors predicting pursuit of an answer

patient expectation (OR = 2.3, p = 0.004)

perceived malpractice liability (OR = 2.1, p = 0.05)
1Covell
DG, Ann Intern Med. 1985;103(4):596-599 (practicing MDs)
2Gorman
3Green
PN, Med Decis Making. 1995;15(2):113-119 (practicing MDs)
ML, Am J Med. 2000;109(3):218-23 (internal medicine residents)
Clinical Scenario
You are caring for a 64-year-old man who has just
developed non-valvular atrial fibrillation. PMH includes
hypertension, type 2 diabetes mellitus, and a remote
history of an upper GI bleed. He has no history of stroke
or TIA.
An echocardiogram shows an EF of 50% and mildly dilated
left atrium. Initial attempts at cardioversion were
unsuccessful. You opt for a rate control strategy and
consider the options for primary prevention of stroke
(aspirin versus warfarin).
Step 1: Ask
Identify information and translate this into
answerable clinical questions
Background vs. Foreground Questions
Background question
Addresses general knowledge that would help clinicians
better understand a particular disorder, health state,
diagnostic test, treatment, or other aspect of health care
• What causes non-valvular afib?
• What left atrial size puts a patient at risk for afib?
• What are the recommendations for cardioversion in
afib?
Background vs. Foreground Questions
Foreground question
Addresses specific knowledge to inform clinical
decisions or actions.
P
I
C
O
Background vs. Foreground Questions
Foreground question
Addresses specific knowledge to inform clinical
decisions or actions.
Patient/
Population
Intervention/
Exposure
Comparison
Outcome
Background vs. Foreground Questions
Foreground question
Addresses specific knowledge to inform clinical
decisions or actions.
Patient/
Population
How would I describe a patient or group of
patients similar to mine?
Intervention/ Which main intervention (exposure, finding,
Exposure
test, risk factor) am I considering?
Comparison
What is the main alternative to the
intervention?
Outcome
What can I hope to accomplish?
What could this exposure really affect?
Question Classification
Question
Intervention/
Exposure
•
•
•
•
•
•
physical finding
risk factor
exposure
diagnostic test
treatment
maneuver
clinical exam
prognosis
harm
diagnosis
therapy
prevention
Foreground Question (PICO)
Therapy/Prevention Question In Action
Patient
Intervention
Comparison Outcome
Foreground Question (PICO)
Therapy/Prevention Question In Action
Patient
64 y/o man
Non-valvular
afib
Hypertension
Diabetes
GI bleed in past
Intervention
Comparison Outcome
Foreground Question (PICO)
Therapy/Prevention Question In Action
Patient
Intervention
64 y/o man
aspirin
Non-valvular
afib
Hypertension
Diabetes
GI bleed in past
Comparison Outcome
Foreground Question (PICO)
Therapy/Prevention Question In Action
Patient
Intervention
64 y/o man
aspirin
Non-valvular
afib
Hypertension
Diabetes
GI bleed in past
Comparison Outcome
warfarin
Foreground Question (PICO)
Therapy/Prevention Question In Action
Patient
Intervention
64 y/o man
aspirin
Non-valvular
afib
Hypertension
Diabetes
GI bleed in past
Comparison Outcome
warfarin
primary
prevention of
stroke
Why Ask Clinical Questions
So Specifically?
Why Ask Clinical Questions
So Specifically?
• Use time wisely
• Search efficiently (sources and search terms)
• Know “when to stop”
• Integrate evidence with clinical context and patient
preferences in decision-making
• Communicate clearly with other clinicians
Step 2: Acquire
Efficiently acquire the best evidence
Clinical question
MEDLINE search for original
clinical research studies
Critically appraise each article
for it is validity and usefulness
Summarize results
Customize for your patient
Make a decision
EBM 1992
EBM 2015
Appraisal mode
Summary
mode (“Doer”)
(“User”)
Ask
Ask
Acquire
Appraise
Apply
Apply
Acquire
Appraise
Guyatt GH, BMJ. 2000;320(7240):954-5
Straus, Evidence-based Medicine, 2005
Haynes RB, ACPJC 2001;134(2):A11-A13
Akl EA, Med Teach. 2006;28(2):192-194
McColl A, BMJ 1998;316:361-5
Hierarchy of EBM Resources
systems
summaries
synopses of syntheses
syntheses
synopses of studies
studies
Full integration (CDSS)
EMR and POE
push technology
patientEvidence
specific info
Clinical
All questions for
ACP
Smart Medicine
condition
UpToDate
DARE
EBM guidelines
health-evidence.ca
ACPJC, EBM journal
Systematic reviews
Single
focused
Cochrane
library
ACPJC
on line
SRs inquestion
journals
EBM
Journal
SRs in
guidelines
Medline or PubMed
(clinical queries)
BMJ Updates
ACPJC plus
DiCenso A, Bayley L, Haynes RB. Editorial: Accessing preappraised evidence: fine-tuning
the 5S model into a 6S model. Ann Intern Med. 2009;151(6):JC3-2-
“Specialized” EBM Summaries
• Specialized
– JAMA Rational Clinical Exam (clinical findings)
– USPSTF Guide (screening, counseling,
immunizations, chemoprophylaxis)
Summaries
•
•
•
•
Explicit and preferably exhaustive search strategy
Explicit criteria for inclusion of articles
Explicit and preferably accepted appraisal criteria
Inferences and recommendation based on highest
level of evidence (and include citations)
• Revised and updated regularly
Yes, There’s an App for That
iPhone
Yes, There’s an App for That
iPhone
Yes, There’s an App for That
iPhone
Yes, There’s an App for That
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Practice
“In a 64 year-old man with non-valvular a-fib, hypertension,
diabetes and a past GI bleed, is the use of aspirin as effective as
wafarin in the primary prevention of stroke?”
Studies
PubMed www.pubmed.gov
Syntheses
Cochrane www.thecochranelibrary.com
Summaries
Clinical Evidence www.clinicalevidence.com
National Guidelines Clearninghouse www.guidelines.gov
UpToDate www.uptodate.com
PubMed4Hh App
ACP Smart Medicine
Guideline Central App