Transcript Evidence-based medicine

Evidence-Based Medicine
History
 In the 1980s, in the northeastern
United States studies showed that there
were large variations in the amount of
care delivered to similar populations.
 The variation rate in the performance
of cataract surgery was 2000%.
History
Physicians failed to recommend
medications up to 10 years after they
had been shown to be effective
Continue to recommend treatments
up to 10 years after they have been
shown to be useless
Definition
 "Evidence-based medicine is the
integration of best research evidence
with clinical expertise and patient
values."
Sackett, D. L. (2000). Evidence-based medicine: How to
practice and teach EBM(2nd ed.). Edinburgh; New York:
Churchill Livingstone.
The four elements to
evidence-based health care
 Clinical expertise: the clinician’s cumulated
experience, education, and clinical skills
 Patient values: The patient brings to the
encounter his or her own personal and unique
concerns, expectiations, and values.
 Best Research Evidence: usually found in
clinically relevant research that has been
conducted using sound methodology
 Evidence-Based Medicine (EBM)
 Evidence-Based Practice (EBP)
 Evidence-Based Clinical Practice (EBCP)
 Evidence-Based Health Care (EBHC)
 Evidence-Based Nursing (EBN)
Sackett’s definition refers to all of these;
EBP and EBHC are more universally used.
Complex literature
 A 2007 analysis of 1016 systematic reviews
from all 50 Cochrane Collaboration Review
Groups found that:
 44% of the reviews concluded that the
intervention was "likely to be beneficial",
7% :"likely to be harmful",
 49% : "did not support either benefit or
harm".
 96% recommended further research
what they would do if faced with
a clinical problem?
Seven alternatives to
evidence based medicine
‫سرشناس و مشهور‬
 Eminence based medicine—The more
senior the colleague, the less
importance he or she placed on the
need for anything as mundane as
evidence.
‫پر حرارت و جوش و خروش‬
 Vehemence based medicine—The
substitution of volume for evidence is
an effective technique for brow beating
your more timorous colleagues and for
convincing relatives of your ability.
‫زبان آوری و آراستگی‬
 Eloquence based medicine -- Sartorial
elegance and verbal eloquence are
powerful substitutes for evidence. -
‫مشیت الهی‬
 Providence based medicine— If the caring
practitioner has no idea of what to do
next, the decision may be best left in
the hands of the Almighty. Too many
clinicians, unfortunately, are unable to
resist giving God a hand with the
decision making.
‫نداشتن اعتماد به نفس‬
 Diffidence based medicine—Some doctors
see a problem and look for an answer.
Others merely see a problem. The
diffident doctor may do nothing from a
sense of despair. This, of course, may be
better than doing something merely
because it hurts the doctor's pride to do
nothing.
‫نگرانی و ترس‬
 Nervousness based medicine—Fear of
litigation is a powerful stimulus to
overinvestigation and overtreatment. In
an atmosphere of litigation phobia, the
only bad test is the test you didn't think
of ordering.
‫اعتماد به نفس باال‬
 Confidence based medicine—This is
restricted to surgeons
Six Steps in practicing EBM
 Craft a clinical question
 Search the medical literature
 Find the study that is most able to answer this
question
 Perform a critical appraisal
 Determine how the results will help you
 Evaluate the results of applying the evidence
Steps in Practicing EBM
Convert the need for information into an
answerable question.
2. Track down the best evidence with
which to answer that question.
3. Critically appraise the evidence for its
validity, impact, and applicability.
4. Integrate the evidence with our clinical
expertise and our patient’s
characteristics and values.
1.
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
 Background questions:
 are those which have been answered in
the past and are now part of the “fiber
of medicine.”
 Answers to these questions are usually
found in medical textbooks
 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.
PICO
P= Patient or problem
I = Intervention, prognostic factor,
or exposure
C=Comparison
O=Outcomes
(T)=Type of Study
 Patient: Middle aged man with diabetes
 Intervention: New drugs
 Comparison: ARB (Losartan)
 Outcome: adverse effects, BP control
 Type: RCT, Metanalysis
Steps in Practicing EBM
Convert the need for information into an
answerable question.
2. Track down the best evidence with
which to answer that question.
3. Critically appraise the evidence for its
validity, impact, and applicability.
4. Integrate the evidence with our clinical
expertise and our patient’s
characteristics and values.
1.
The Evidence Pyramid
Time Spent in Critical Appraisal
Validity/Strength of Inference
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 This meta-analysis demonstrates that valsartan at doses of
160 and 320 mg is more effective in reducing BP than
losartan at the 100 mg dose.
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Steps in Practicing EBM
Convert the need for information into an
answerable question.
2. Track down the best evidence with
which to answer that question.
3. Critically appraise the evidence for its
validity, impact, and applicability.
4. Integrate the evidence with our clinical
expertise and our patient’s
characteristics and values.
1.
Types of Studies
 Case series and Case Reports
 Case control studies
 Cohort studies
 Randomized, controlled clinical trials
 Systematic Reviews
 Meta-analysis
Case series and Case reports
 Collections of reports on the treatment of
individual patients or a report on a single
patient.
 No control groups with which to compare
outcomes, so limited statistical validity.
Case control studies
 Patients who already have a specific condition are compared
with people without the condition. Researcher looks back to
identify factors or exposures possibly associated with the
condition, often relying on medical records and patient recall.
 Less reliable because showing a statistical relationship does
not mean than one factor necessarily caused the other.
 Starts with patients who already have the outcome
and looks backwards to possible exposures.
Cohort studies
 Take a large population who are already taking a particular
treatment or have an exposure, follow them forward over
time, and then compare for outcomes with a similar group
that has not been affected by the treatment or exposure.
 Observational and not as reliable as randomized controlled
studies, since the two groups may differ in ways other than in
the variable under study.
 Starts with the exposure and follows patients
forward to an outcome.
Randomized, controlled clinical trials
 Carefully planned projects that introduce a treatment or
exposure to study its effect on patients.
 Include methodologies that reduce the potential for bias
(randomization and blinding) and allow for comparison
between intervention and control groups.
 Is an experiment and can provide sound evidence of cause
and effect.
 Randomly assigns exposures and then follows
patients forward to an outcome.
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.
Meta-analysis
 Thoroughly examines a number of valid studies on a topic
and combines the results using accepted statistical
methodology to report the results as if it were one large
study.
 The Cochrane Collaboration has done a lot of work in the
areas of systematic reviews and meta-analysis.