Transcript Rick Wallace, MA, MDiv, MAOM, MSLS, EdD, MPH (abd), AHIP February 11,2013 Internal Medicine Grand Rounds.

Rick Wallace, MA, MDiv, MAOM, MSLS,
EdD, MPH (abd), AHIP
February 11,2013
Internal Medicine Grand Rounds
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EBM is "the conscientious, explicit and judicious use
of current best evidence in making decisions about
the care of the individual patient (population). It
means integrating individual clinical expertise with
the best available external clinical evidence from
systematic research."
[Sackett D, BMJ Jan 13 1996;312:71-73]
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Studies of information-seeking habits of physicians
have shown that, when asked, physicians reported that
their practice generated about 2 questions for every 3
patients. It has also been reported that only about
30% of physicians' information needs are met during
the patient visit. Reasons for not pursuing answers to
questions included office textbook collections too old,
lack of knowledge of appropriate resources, and lack
of time to find the needed information.
[Covell DG, Ann Intern Med. 1985 Oct;103(4):596-9]
When observed, investigators found that physicians
actually had about 5 questions for each patient. 52%
of these questions could be answered by the medical
record or hospital information system. Information
resources such as textbooks or MEDLINE could have
answered another 25% of these questions.
[Osheroff JA, Ann Intern Med. 1991 Apr 1;114(7):576-81]
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However, studies have also shown that when
clinicians have access to information, it changes
their patient care management decisions. In 1998,
David Sackett, using an “evidence cart” on rounds,
reported that of 71 information searches to answer
clinical questions, 37 (52%) confirmed the
management decision, but 18 (25%) lead to a new
therapy or diagnostic test and 16 (23%) corrected a
previous plan.
[Sackett, D, JAMA. 1998 Oct 21;280(15):1336-8]
Crowley et al reported similar results. The CAR study
reported on 520 clinical questions for which
residents sought answers in the medical literature. In
53% of the cases the literature confirmed the
management decision, but in 47% of these cases the
literature changed the resident’s orders for
medication, diagnostic test, or prognostic
information given to the patient.
[Crowley S, Acad Med. March 2003 78(3):270-4]
From: http://guides.library.upenn.edu/content.php?pid=192036&sid=1610308
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Systematic Reviews usually focus on a clinical topic
and answer a specific question. An extensive
literature search is conducted to identify studies
with sound methodology. The studies are reviewed,
assessed, and the results summarized according to
the predetermined criteria of the review question.
The Cochrane Collaboration has done a lot of work
in the area of meta-analysis.
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A Meta-analysis will thoroughly examine a number
of valid studies on a topic and combine the results
using accepted statistical methodology to report the
results as if it were one large study. Some clinicians
put Meta-analysis at the top of the pyramid because
part of the methodology includes critical appraisal of
the selected RCTs for analysis.
A systematic review focuses on a specific clinical
question, conducts a systematic review of the
evidence including published and unpublished
studies, and then summarizes the results to present
an answer to the question.
 A meta-analysis follows the structure of a systematic
review but takes the results one step further. It uses
quantitative methods to combine the data from the
individual studies and report the results as if it were
one large study.
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Randomized, controlled clinical trials are carefully
planned projects that study the effect of a therapy on
real patients. They include methodologies that reduce
the potential for bias (randomization and blinding) and
that allow for comparison between intervention groups
and control groups (no intervention).
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Cohort studies take a large population who are already
taking a particular treatment or have an exposure, follow
them forward over time, and compare them for
outcomes with a similar group that has not been
affected by the treatment or exposure being studied.
Cohort studies are observational and not as reliable as
randomized controlled studies, since the two groups may
differ in ways other than in the variable under study.
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Case control studies are studies in which patients who
already have a specific condition are compared with
people who do not have the condition. The researcher
looks back to identify factors or exposures that might
be associated with the illness. They often rely on
medical records and patient recall for data collection.
These types of studies are often less reliable than
randomized controlled trials and cohort studies
because showing a statistical relationship does not
mean than one factor necessarily caused the other.
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Case series and Case reports consist of collections of
reports on the treatment of individual patients or a
report on a single patient. Because they are reports of
cases and use no control groups with which to
compare outcomes, they have no statistical validity.
Studies that show the efficacy of a diagnostic test
are called prospective, blind comparison to a gold
standard study. This is a controlled trial that looks at
patients with varying degrees of an illness and
administers both diagnostic tests -- the test under
investigation and the "gold standard" test -- to all of
the patients in the study group.
 Cross-sectional studies describe the relationship
between diseases and other factors at one point in
time (usually) in a defined population. Cross
sectional studies lack any information on timing of
exposure and outcome relationships and include
only prevalent cases.
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Therapy -- how to select treatments to offer
patients that do more good than harm and that
are worth the efforts and costs of using them.
Diagnosis
a.
b.
3.
4.
Differential Diagnosis -- when considering the
possible causes of a patient's clinical problem,
how to rank them by likelihood, seriousness and
treatability
Diagnostic Testing -- how to select and interpret
diagnostic tests, in order to confirm or exclude a
diagnosis, based on considering their precision,
accuracy, acceptability, expense, safety, etc.
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)
• Clinical examination -- how to properly
gather and interpret findings from the
history and physical examination
• Prevention -- how to reduce the chance
of disease by identifying and modifying
risk factors and how to diagnose early
by screening
• Cost-Analysis -- how to compare the
cost and consequences of different
treatments and tests
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Start with the population -- a clinical
problem /question arises out of the care of a
patient
Your patient is a 68 year old woman with a history of known CAD, s/p
Inferior MI 7 years ago. Following her MI, she did extremely well.
She has been on aspirin and b-blocker therapy. For the past 2 years
she had been walking 2 miles four times each week without pain
until 3 weeks ago when she noted exertional pain when she goes
for her walk. She presented to the ER this evening when she had
4/10 substernal pain while sitting down at dinner. She denied SOB,
N/V or diaphoresis. In the ER she was treated with aspirin, oxygen
and sublingual nitroglycerine with complete resolution of her pain.
Her initial physical examination was significant for HR 100 bpm, BP
105/70, clear lungs and heart exam without murmurs or gallops.
She had no signs of CHF. Her presenting EKG showed anterior ST
depression which resolved post nitroglycerine. She is admitted to
the hospital.
Question #1: The intern is writing the admission orders and
asks you whether to treat this patient with Heparin at
this time. Do you want to treat this patient with heparin?
Question #2: The medical student adds that the patient was
told at the time of her previous MI that she had some
blood in her stools. She doesn’t recall receiving any
transfusions for this and doesn’t recall what work up was
done because “she had so many tests at that time”. You
don’t have access to these medical records. At this time,
she is guaiac negative. The patient is concerned about
bleeding and would like to know more about her risk of
bleeding. Because you care so much about the learning
experience of your medical student
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Construct a relevant, answerable question
derived from the case
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Background questions:
 What’s the latest on treating otitis media?
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Foreground questions:
 (P) patient and/or problem
 (I) intervention
 (C) comparison intervention (if relevant)
 (O) clinical outcomes.
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P patients with
unstable Angina
 I heparin plus aspirin
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C aspirin alone
O prevent MI and
death
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P patients with
unstable Angina
 I heparin plus aspirin
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C aspirin alone
O cause bleeding
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Formulating the clinical question is done to
focus the information need and to facilitate
searching the literature. So when you define
your PICO think about it in terms of
searching the literature. You want to end up
with a question that makes sense and can be
effectively searched.
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You might not need to use all the terms in
the PICO for the search strategy, but they can
help you decide which specific articles are
most appropriate for your case.
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In patients with Unstable Angina, is heparin
plus aspirin more effective than aspirin alone
in preventing MI and death?
In patients with Unstable Angina, is heparin
plus aspirin more likely than aspirin alone to
cause bleeding?
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Select the appropriate resources and conduct
a search
JAMA. 1996 Sep 11;276(10):811-5.
Adding heparin to aspirin reduces the incidence of myocardial
infarction and death in patients with unstable angina. A metaanalysis.
OBJECTIVE: To estimate the risk of myocardial infarction (MI)
and death in patients with unstable angina who are treated
with aspirin plus heparin compared with patients treated with
aspirin alone.
CONCLUSIONS: Our findings are consistent with a 33%
reduction in risk of MI or death in patients with unstable angina
treated with aspirin plus heparin compared with those treated
with aspirin alone. The bulk of evidence suggests that most
patients with unstable angina should be treated with
both heparin and aspirin.
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What is the ideal resource?
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Easy to use
Fast, reliable connection
Comprehensive /Full Text
Allows the separation of ‘junk” from “gold”
(quality of the search interface)
 Provides or reviews the primary data
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Appraise that evidence for its validity
(closeness to the truth) and applicability
(usefulness in clinical practice)
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Key issues for evaluating therapy studies:
F-R-I-S-B-E
 Follow-up (80% or better)
 Randomization and concealed allocation
 Intention to Treat
 Same at Baseline (established at the start of the trial)
 Blinding (the more blinding the better)
 Equal Treatment
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Key issues for diagnostic studies:
 Independent blind comparison with gold standard
 Appropriate spectrum of patients
 All patients receive both tests
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Key issues for prognosis studies:
 Well-defined sample of patients
 Similar prognostic factors
 Follow-up
 Objective outcome criteria
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Key issues for etiology/harm studies:
 Similarity of comparison groups
 Outcomes and exposure measured the same for
both groups
 Follow-up of sufficient length
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Key issues for Systematic Review/Meta
Analysis:
 Focused question
 Thorough review of the literature
 Clear validity criteria
 Reproducible assessments of studies
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Absolute Risk Reduction is the arithmetic
difference between the rates of events in the
experimental and control group. An Absolute
Risk Reduction (ARR) refers to the decrease of
a bad event as a result of the intervention. An
Absolute Benefit Increase (ABI) refers to the
increase of a good event as the result of the
intervention.
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Relative Risk (RR) or Risk Ratio (RR) is the
ratio of risk in the exposed group to the risk in
the unexposed group. In other words, it's the
probability of an event in the treated group
divided by the probability of an event in the
control group. If the RR is greater than 1 there
is a higher risk of the event occurring; if the
RR is 1 the risk is equal; if the RR is less than 1
there is a lower risk of the event happening.
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Relative Risk Reduction (RRR) is the
proportional reduction in risk between the
rates of events in the control group and the
experimental group. Relative Risk Reduction is
often a larger number than the ARD and
therefore may tend to exaggerate the
difference.
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Numbers Needed to Treat (NNT) is the
number of patients who need to be treated to
prevent one bad outcome or produce one
good outcome. In other words, it is the
number of patients that a clinician would
have to treat with the experimental treatment
to achieve one additional patient with a
favorable outcome. The smaller the NNT, the
more effective the treatment.
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Confidence Intervals are a measure of the
precision of the results of a study. For
example, "36 [95% CI 27-51]", a 95%CI range
means that if you were to repeat the same
clinical trial a hundred times you can be sure
that 95% of the time the results would fall
within the calculated range of 27-51. Wider
intervals indicate lower precision; narrow
intervals show greater precision.
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P value refers to the probability that any
particular outcome would have arisen by
chance. (The smaller the P value the less likely
the data was by chance and more likely due to
the intervention.) Standard scientific practice,
usually deems a P value of less than 1 in 20
(expressed as P=.05) as "statistically
significant". The smaller the P value the
higher the significance.
Sensitivity: measures the proportion of patients
with the disease who also test positive for the
disease in this study.
 Specificity: measures the proportion of patients
without the disease who also test negative for the
disease in this study.
 Sensitivity and specificity are characteristics of the
test but do not provide enough information for the
clinician to act on the test results.
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Likelihood ratios: expresses the relative
likelihood that a given test result would be
expected in a patient with the target disorder
compared to the likelihood that the same
result would be expected in a patient without
that disorder
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Prognostic Factor is a patient characteristic
that can predict that patient's eventual
outcome:
 demographic: e.g. age, sex, weight
 disease-specific: e.g. tumor stage
 comorbid: other co-existing conditions
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Relative Risk is the risk of the adverse
outcome in the exposed group divided by the
risk of the adverse outcome in the unexposed
group.
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Odds Ratio is the odds of exposure in patients
who have the adverse outcome or bad event
compared to the patients who do not have
the adverse outcome or bad event. (An OR of
3.0 means that patients with the adverse
outcome were 3 times more likely to have
been exposed than were patients without the
adverse outcome.)
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Return to the patient (population) -integrate that evidence with clinical
expertise, patient preferences and apply it to
practice
Did I ask the right question?
Were the necessary EBM resources readily available?
Did I know how to access and use them?
Was I able to obtain full text information?
Did I find a useful answer?
Did I actually use the findings in your clinical
practice?
 What could I have done better?
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We will work with you one-on-one or in
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[email protected]
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Katie Wolf, MLIS
[email protected]
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Rick Wallace, MSLS, EdD
[email protected]
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