Transcript Case Presentation

Evidence Based Medicine
By Mohamed Elreedy
Resident of Anesthesiology
Ain Shams University Hospitals
Let’s Read This !!!
Mohamed a 60 years old patient medically free, admitted to ICU
post-operatively after major abdominal surgery. Post operatively he
was admitted to surgical ICU. After 24 hours from ICU admission
the patient started to suffer from low grade fever 37.5°C,tachycardia
(100 beat/min) and increased leucocytes count (16000 cells/mm³).
Over the last 12 hours his urine output was less than 0·5
mL/kg/hour. Pre-operatively he had neither history of renal disease
nor any previous renal condition and his urine output was adequate.
You though to better start low Dopamine dose infusion
(< 3 μg/kg/min) in an attempt to restore and maintain his renal blood
flow and urine output. You decide to research this question before
proceeding on.
What Is Evidence Based Medicine?
 The most common definition of EBM is taken
from Dr. David Sackett.
 EBM is the integration of clinical expertise,
patient values, and the best evidence into the
decision making process for patient care.
 The evidence, by itself, does not make a
decision for you.
 Evidence-based medicine requires new skills of
the clinician, including efficient literaturesearching, and the application of formal rules
of evidence in evaluating the clinical literature.
Elements Of EBM
 Production of evidence through
research and scientific review.
 Production and dissemination of
evidence-based clinical guidelines.
 Implementation of evidence-based, costeffective practice through education and
management of change.
 Evaluation of compliance with agreed
practice guidance and patient outcomes
– this process includes clinical audit.
Why the sudden interest in EBM?
 It may have been started………
 In the current era, they were consolidated and named
EBM in 1992
 The subsequent rapid spread of EBM has arisen from 4
realizations and is made possible by 5 recent
developments.
The realizations are
1. Our daily need for valid information.
2. The inadequacy of traditional sources for
this information
3. The disparity between our diagnostic
skills and clinical judgment.
4.
Our inability to afford more than a few
seconds per patient for finding and
assimilating this evidence
However, 5 developments have permitted us to
turn this state of affairs around
1. Development of strategies for efficiently tracking down and
appraising evidence.
2. The creation of systematic reviews.
3. The creation of evidence-based journals of secondary publication.
4. The creation of information systems for bringing the foregoing to
us in seconds.
5. The identification and application of effective strategies for lifelong learning and for improving our clinical performance.
What are systematic reviews?

Systematic reviews are a way of
summarizing research evidence.

High-quality systematic reviews take great
care to find all relevant studies published
and unpublished, assess each study,
synthesize the findings from individual
studies in an unbiased way and present a
balanced and impartial summary of the
findings with due consideration of any flaws
in the evidence.

Not all published systematic reviews have
been produced with meticulous care
How do we actually practice EBM?
EBM comprises 5 steps, they are:
1. Converting the need for information into an answerable question
2. Tracking down the best evidence with which to answer that
question
3. Critically appraising that evidence
4. Integrating the critical appraisal with our clinical expertise
5. Evaluating our effectiveness and efficiency in executing Steps 1-4
and seeking ways to improve them both for next time.
Modes of Practicing Medicine
We can identify 3 different "modes"
of practice:
 For the conditions we encounter
every day “Appraising" mode.
 For the conditions we encounter
less often “Searching" mode.
 The problems we're likely to
encounter very infrequently
“Replicating" mode.
Can clinicians actually practice EBM?
In a survey of UK GPs
Getting To The Evidence Quickly

In a busy (180+ admissions per month) inpatient medical service

Electronic summaries of evidence
10 seconds
previously appraised

Summary journals to working rounds
25 seconds
Does providing evidence-based care
improve outcomes for patients?
 No such evidence is available from randomized

trials
This is because no investigative team or research
granting agency has yet overcome the problems of
sample-size, contamination, blinding, ethical
concerns and long-term follow-up which such a
trial requires.
For positive examples
 Myocardial infarction survivors
prescribed Aspirin or Beta-blockers
have lower mortality rates than
those who aren't prescribed these
drugs.
 Where clinicians use more Warfarin
in stroke unit referrals, stroke
mortality declines by >20%.
For Negative examples

Patients undergoing carotid
surgery despite failing to
meet evidence-based
operative criteria, when
compared with operated
patients who meet those
criteria, are more than 3
times as likely to suffer major
stroke or death in the next
month.
What Meta-analysis?

Meta-analysis is a statistical technique for
combining the findings from independent
studies.

The validity of the meta-analysis depends on
the quality of the systematic review on
which it is based.

Good meta-analyses aim for complete
coverage of all relevant studies, look for the
presence of heterogeneity and explore the
robustness of the main findings using
sensitivity analysis.
Evidence-based medicine Issues
Opponents
Proponents
EBM is "old hat".
The new focus on EBM "formalizes"
that "old hat"
EBM is "cook book medicine".
EBM should be one part of the
process.
EBM is the mindless application of The last step in the EBM process is to
population studies to the treatment of decide whether or not the information
the individual.
and results are applicable to your
patient and to discuss the results with
the patient.
Often there is no randomized
controlled trial or "gold standard" in
the literature to address the clinical
question.
Clinicians might consider the
"evidence pyramid”
Great difficulty in getting access to the
evidence
Librarians can help
What’s Critical Appraisal?

Critical appraisal is the process of
systematically examining research
evidence to assess its validity,
results and relevance before using
it to inform a decision.

Randomized controlled trials and
systematic reviews are not
automatically of good quality and
should be appraised critically.
What are the other uses of EBM?

It reinforces the need for
communication skills.

It provides an effective life-long
learning.

Identifying the questions for
which no satisfactory evidence
exists.

It provides a common language.
The EBM Process
(based on example on http://www.hsl.unc.edu/Services/Tutorials/EBM/Question.htm)
The Patient
1. Start with the patient: a clinical problem/
question arises out of the care of the patient.
The Question
2. Construct a well-built question derived from the
case.
Mohamed a 60 years old patient medically free, admitted to ICU post-operatively
after major abdominal surgery. Post operatively he was admitted to surgical ICU.
After 24 hours from ICU admission the patient started to suffer from low grade fever
37.5°C,tachycardia (100 beat/min) and increased leucocytes count (16000 cells/mm³).
Over the last 12 hours his urine output was less than 0·5 mL/kg/hour. Pre-operatively
he had neither history of renal disease nor any previous renal condition and his urine
output was adequate.
You though to better start low Dopamine dose infusion (< 3 μg/kg/min) in an attempt
to restore and maintain his renal blood flow and urine output. You decide to research
this question before proceeding on.
Anatomy of a Good Clinical Question
1.
2.
3.
4.
Patient or problem
Intervention, prognostic factor, or exposure
Comparison
Outcomes
Patient / Problem
Early renal dysfunction
Intervention
Dopamine
Comparison, if any
None, placebo
Outcome
Reducing the risk of renal failure
Type of question
Diagnosis
How to select and interpret diagnostic
tests
Therapy
How to select treatments to offer
patients that do more good than harm
Prognosis
How to estimate the patient's likely
clinical course over time and
anticipate likely complications of
disease
Harm/Etiology
How to identify causes for disease
(including iatrogenic forms)
Types Of Studies
As you move up the pyramid the amount of available literature
decreases, but increases in its relevance to the clinical setting.
The type of question is important
and can help lead you to the best study design
Type of Question
Suggested best type of Study
Therapy
RCT>cohort > case control > case series
Diagnosis
prospective, blind comparison to a gold
standard
Etiology/Harm
RCT > cohort > case control > case series
Prognosis
cohort study > case control > case series
Prevention
RCT>cohort study > case control > case series
Clinical Exam
prospective, blind comparison to gold standard
Cost
economic analysis
Our Question
For our patient, the clinical
question might be:
In critically ill patients with
early renal dysfunction, is
low dopamine administration
effective in reducing the risk
of renal failure?
The Literature Search
The
Resource
3. Select the appropriate
resource(s) and conduct a search

Large databases such as MEDLINE will give
you access to the primary literature

For this question, we have chosen MEDLINE
as our resource. MEDLINE is the most
comprehensive resource for health-related
literature searches and is accessible to
everyone through PubMed
Formulate Your Strategy
Patient Population
Critically ill patients
with early renal
dysfunction
Early renal dysfunction
limited to critically ill patients
Intervention
Dopamine
Dopamine
Comparison (if any)
None or placebo
Outcome
Reducing the risk of
renal failure
Type of Question
Therapy
Type of Study
RCT
Reducing the risk of renal
failure
Limit to randomized
controlled trial as publication
type
Constructing a well-built clinical question can lead directly to a
well-built search strategy
Step 1: Search each important concept
separately.

Using MeSH search (Medical Subject
Heading) to be sure it found the appropriate
MeSH Terms and Text Words.
Your Key Words are:
1. Renal Dysfunction
2. Low dopamine dose

Step 2: Combine the separate sets of
articles

You need to combine them to identify those
articles that contain the 2 terms. In PubMed you
must use the "#".
Step 3: Limit the results to the
appropriate publication type and human
Our Limits:
1. RCT
2. Humans

Review the results

Review the titles and abstracts to identify
potentially relevant articles
Evaluating the Results
The evaluation
4.Appraise that evidence for its validity
(closeness to the truth) and applicability
(usefulness in clinical practice)
There are three basic questions that need to be answered for every type of
study:
1. Are the results of the study valid?
2. What are the results?
3. Will the results help in caring for my patient?
 The information is found primarily in the study methodology
Once you have determined that the study methodology is valid, you
must examine the results and their applicability to the patient.
Clinicians may have additional concerns such as whether the study
represented patients similar to his/her patients, whether the study
covered the aspect of the problem that is most important to the
patient, or whether the study suggested a clear and useful plan of
action
Are the results of this therapy study
valid?
1. Was the assignment of patients to
treatment randomized?
2. Were all the patients who entered the trial
properly accounted for at its conclusion?
3. Were patients analyzed in the groups to
which they were (originally) randomized?
4. Were patients, clinicians, and study
personnel "blind" to treatment allocation?
5. Were the groups similar at the start of the
trial?
6. Aside from the experimental intervention,
were the groups treated equally?
7. Are the results of this study valid?
Return to the Patient
The patient 5. Return to the patient -- integrate that evidence
with clinical expertise, patient preferences and apply
it to practice
Evaluate Your Performance
Self-evaluation 6. Evaluate your performance with this patient
Now what’s BETs (Best Evidence Topics)?

Physicians need rapid access to the best
current evidence on a wide range of
clinical topics, But where to find it?

BETs were developed in the Emergency
Department of Manchester Royal
Infirmary, UK, to provide rapid evidencebased answers to real-life clinical
questions.

BETs are designed for the working
clinician and therefore do not normally
search the "grey literature"