An Introduction to Evidence Based Medicine
Summary
TLDRThis video introduces the concept of Evidence-Based Medicine (EBM), emphasizing its core principles beyond merely quoting medical studies. EBM involves integrating the best available research with clinical experience and patient values. The speaker outlines the five A's of EBM: Assess, Ask, Acquire, Appraise, and Apply. Different types of clinical studies, such as observational studies, clinical trials, and reviews, are explained, with a focus on Randomized Controlled Trials (RCTs). The video highlights both the advantages and limitations of EBM, underscoring the importance of critical thinking, experience, and patient input in medical decision-making.
Takeaways
- 📚 Evidence-based medicine (EBM) is not about memorizing landmark studies but integrating best research evidence with clinical experience and patient values.
- 📝 The 5 A's of EBM: Assess the clinical problem, Ask structured clinical questions (using PICO format), Acquire the evidence, Appraise the evidence, and Apply it to the patient.
- 👀 Observational studies include cohort, case-control studies, and case reports, where investigators watch patients without intervention.
- 💊 Randomized Controlled Trials (RCTs) involve giving interventions to some patients, with a control group receiving either placebo or conventional treatment.
- 🔬 Meta-analyses combine data from multiple smaller studies, sometimes revealing significant relationships that may not have been clear in individual studies.
- ⚖️ The hierarchy of evidence places expert opinion at the bottom and meta-analyses of RCTs at the top, but this ranking has limitations and biases.
- 💡 Expert opinion can still be valuable, as it’s often built from years of analyzing evidence, but may be underestimated in the traditional hierarchy.
- ⏳ EBM can be time-consuming, and physicians often don't have the time to rigorously appraise every clinical decision in a structured way.
- 💼 Conflicts of interest, such as pharmaceutical industry sponsorship, can bias clinical trial results and influence what gets published.
- 🤔 Clinical decisions often involve uncertainty; EBM is about using evidence along with clinical judgment and patient values, not just following rigid rules.
Q & A
What is the primary focus of the video?
-The video focuses on introducing evidence-based medicine (EBM) and how to read and apply medical literature effectively.
What is a common misconception about evidence-based medicine (EBM)?
-A common misconception is that EBM is just about memorizing key studies and quoting them, rather than critically appraising the evidence and applying it to specific patient cases.
How does the video define evidence-based medicine (EBM)?
-EBM is defined as the integration of the best research evidence with clinical experience and patient values, rather than simply relying on medical literature alone.
What is the 5 A’s framework of EBM mentioned in the video?
-The 5 A's framework includes: Assess the clinical problem, Ask structured clinical questions, Acquire the evidence, Appraise the evidence, and Apply the evidence to the patient.
What is a PICO question, and how is it used in EBM?
-A PICO question structures clinical inquiries using four elements: Patient, Intervention, Comparison, and Outcome. It helps in formulating research questions and assessing evidence from clinical trials.
What are the three major types of clinical studies mentioned?
-The three major types of clinical studies are observational studies, clinical trials, and reviews (including meta-analyses).
What distinguishes randomized controlled trials (RCTs) from other study designs?
-RCTs involve randomizing patients to either an intervention or control group, allowing for rigorous evaluation of a single variable’s impact. They are considered a gold standard but can be time-consuming and expensive.
What are the potential limitations of relying on randomized controlled trials (RCTs)?
-Limitations include their high cost, time requirements, ethical constraints, and potential for bias. They also require external oversight, such as Institutional Review Boards (IRBs).
Why is the traditional hierarchy of evidence criticized in the video?
-The hierarchy can lead to the assumption that studies ranked higher, like meta-analyses, are always superior to those ranked lower, like expert opinion, which may overlook important nuances or biases in individual studies.
What are some of the challenges of practicing evidence-based medicine (EBM) mentioned in the video?
-Challenges include the time required to appraise literature, the need for statistical knowledge, access to relevant studies, and the influence of publication bias and conflicts of interest in medical research.
Outlines
📚 Introduction to Evidence-Based Medicine (EBM)
The speaker introduces the concept of evidence-based medicine (EBM), emphasizing that it is more than just quoting landmark studies. EBM involves integrating research evidence with clinical experience and patient values. The speaker criticizes the casual use of study citations without critical discussion, underscoring that EBM requires deeper understanding beyond memorizing trial outcomes.
🔍 The Five A's of EBM
The speaker introduces the 'Five A's' framework for practicing EBM: assess the clinical problem, ask structured clinical questions (using the PICO format), acquire evidence, appraise the evidence, and apply it to the patient. An example using COPD is provided, illustrating how to form a clinical question in the PICO format (Patient, Intervention, Comparison, Outcome). The speaker explains that future videos will delve deeper into these topics.
🧪 Types of Clinical Studies
The speaker explains different types of clinical studies: observational studies (cohort, case-control, and qualitative case reports), clinical trials (specifically randomized controlled trials or RCTs), and reviews (standard reviews and meta-analyses). Meta-analyses combine data from multiple studies, revealing trends or inconsistencies. The speaker stresses the value of RCTs in EBM, as they rigorously test interventions, but acknowledges their limitations, such as cost and ethical concerns.
⚖️ Randomized Controlled Trials (RCTs) Explained
The speaker breaks down randomized controlled trials (RCTs), explaining their structure: randomizing participants into intervention or control groups, often using placebos or standard treatments. Well-designed RCTs are double-blinded, meaning neither the participants nor the clinicians know who is receiving the intervention. The strength of RCTs lies in their ability to isolate the effect of an intervention, though they are expensive, time-consuming, and subject to ethical oversight.
📊 Hierarchy of Evidence and Its Challenges
The speaker presents a conventional 'hierarchy of evidence' used in EBM, ranking qualitative studies lower and meta-analyses higher. However, they criticize this hierarchy for oversimplifying study quality and undervaluing expert opinion. The speaker introduces clinical guidelines, which represent expert recommendations, and notes that while guidelines are valuable, they can be outdated and biased.
⏳ Practical Limitations of EBM
The speaker discusses practical challenges in implementing EBM, such as time constraints, limited access to literature, and the need for statistical knowledge. They highlight issues like publication bias and conflicts of interest, where pharmaceutical companies may influence study outcomes. These limitations affect the accuracy of medical literature, making it difficult to rely solely on evidence.
⚖️ EBM’s Uncertainty and Complexity in Practice
The speaker reflects on the inherent uncertainty in practicing EBM, noting that clinical decisions require clear actions, yet evidence is rarely black and white. Even high-quality studies may not offer definitive answers, making decision-making complex. EBM involves balancing evidence with clinical experience and patient preferences, recognizing that medicine is not reducible to strict algorithms.
🎯 Conclusion: The Role of EBM in Clinical Practice
In conclusion, the speaker reiterates that EBM is not just about evidence, but about integrating research with clinical judgment and patient values. While evidence appraisal is crucial, the practice of medicine also requires instinct, communication, and adaptability. The speaker encourages viewers to stay tuned for more videos in the series and thanks them for watching.
Mindmap
Keywords
💡Evidence-Based Medicine (EBM)
💡Randomized Controlled Trial (RCT)
💡Meta-analysis
💡Clinical Guidelines
💡Publication Bias
💡Cohort Study
💡Blinding
💡Case-Control Study
💡PICO Framework
💡Hierarchies of Evidence
Highlights
Introduction to evidence-based medicine (EBM) and its purpose beyond simply quoting landmark studies.
Definition of EBM by David Sackett as the integration of best research evidence with clinical experience and patient values.
The five A's of EBM: Assess, Ask (using PICO format), Acquire, Appraise, and Apply.
Explanation of PICO: Patient, Intervention, Comparison, and Outcome, and its role in structuring clinical questions.
Overview of the three major categories of clinical studies: observational studies, clinical trials, and reviews.
Observational studies involve passive observation, either prospectively or retrospectively, and include cohort studies, case-control studies, and case reports.
Clinical trials involve actively intervening, with the randomized controlled trial (RCT) being the major type.
Reviews can be qualitative (standard reviews) or quantitative (meta-analyses). Meta-analyses combine data from multiple studies to find relationships or conclude effectiveness.
Details on randomized controlled trials (RCTs), including terms like 'controlled,' 'randomized,' and 'double-blinded,' which enhance reliability.
Hierarchy of evidence: most qualitative forms of evidence are considered less important, with meta-analyses often at the top. However, this hierarchy has limitations.
Limitations of the evidence hierarchy, such as undervaluing expert opinion and the challenges of biased or conflicting meta-analyses.
Clinical guidelines are an alternative to the evidence hierarchy, often considered an improvement but also subject to delays and biases.
Challenges of EBM implementation include time constraints, lack of access to medical literature, and the need for understanding statistics.
Conflicts of interest in the medical literature, such as publication bias and the influence of pharmaceutical sponsorship.
Importance of applying evidence alongside clinical experience and patient values, acknowledging the role of uncertainty and the non-algorithmic nature of medicine.
Transcripts
hello everyone it's Eric from Stanford
University and strong medicine today to
kick off a short series on reading and
applying the medical literature I'll be
giving a brief introduction to
evidence-based medicine or ebm for
[Music]
[Applause]
short I think when some doctors talk
casually about evidence-based medicine
they do so as if ebm was just about
being able to quote Landmark studies for
example I can't count the number of
times that I've been on rounds and some
clinical question has come up and a
physician there has said oh but as per
such and such trial we should do this
and everyone else on rounds you know
nons their head approvingly uh impressed
by the person's recollection of some
catchy study acronym like accomplish or
Miracle or cure and everyone there takes
it for granted that the punch line that
was cited applies to the patient in
question and should dictate how here or
she should be treated without any
critical discussion of the paper or
situation at
all that is not practicing
evidence-based medicine ebm is not
remotely the same thing as memorizing
the abstracts of the 50 most important
trials in one's
field so what is ebm ebm Pioneer David
sacket from MCM Master University
defined ebm as this the integration of
best research evidence with clinical
experience and patient values in other
words ebm is not just about the
literature let me show you a framework
for ebm in practice I'm generally not a
fan of Sil acronym demonics because they
usually feel forced but this one works
pretty well the five A's of ebm first
assess meaning identify the clinical
problem
next is ask which means to structure the
clinical question typically using a
format called Pico for a clinical trial
Pico stands for patient intervention
comparison and outcome so Pico question
might be for adults with Advanced COPD
does ziyin compared to Placebo result in
fewer COPD
exacerbations the next a stands for
acquire the evidence then appraise
meaning evaluate the evidence found last
is to apply the evidence to your
patient I'll be covering some of these
A's in more detail in future videos in
this series but to get us started with
common ebm terminology let's talk about
the different types of studies that we
might come across when acquiring the
evidence we can classify clinical
studies into three major categories
first are observational studies in
observational studies the investigators
play a passive role watch watching
patients either retrospectively or
prospectively but without directly
intervening observational studies can be
quantitative such as cohort and case
control studies or they can be
qualitative such as a case report in
which a description is provided of a
single patient presentation or disease
course or a case series which is a
non-statistical summary of multiple
individual patient
presentations the next broad category
are clinical trials in clinical trials
the investigators play an active role by
administering some type of intervention
to either all or some of the patients in
a specific
population the major type of clinical
trial is the randomized controlled trial
or
RCT the final category of studies are
reviews The Standard review paper is a
predominantly qualitative summary of all
the knowledge and prior research about a
specific disease or intervention a meta
analysis is a quantitative summary which
uses standardized statistical methods to
combine data from multiple individual
trials which all looked at identical or
nearly identical questions by combining
many smaller studies metaanalyses can
find meaningful relationships that may
not have been parent when each of the
individual studies were analyzed
separately due to their small sample
sizes or other factors or conversely a
met analysis of multiple conflicting
studies May conclude that a particular
particular treatment results in no
meaningful benefit even if some of the
included studies showed that there had
been the randomized controlled trial in
particular is often held up as the
primary source of evidence used in
evidence-based medicine and therefore
I'll discuss it in more detail let's go
through each word working backwards
first is the most obvious one trial this
means that investigators are giving some
patients or study subjects an
intervention
controlled means that some of the study
subjects receive the intervention While
others don't those who don't receive
either a placebo that is
indistinguishable from the intervention
from the patient's point of view or they
receive an established conventional
treatment if providing a placebo for the
disease in question is felt to be
unethical the non-intervention group
whether receiving Placebo or
conventional treatment is called the
control group and randomized means that
whether a study subject is assigned the
intervention or the control is decided
randomly furthermore the most
well-designed rcts are also double
blinded this means that neither the
study subjects nor the clinicians tasked
with assessing outcomes are aware of
which group an individual subject was
randomly assigned
to the most important advantage of rcts
over other study designs is that
investigators can rigorously evaluate
the effect of changing a single variable
able that is if the randomization of
patients to the intervention and control
groups is done well any difference in
outcome between the two groups will
presumably be due to the differences in
the effectiveness of the intervention
versus the control at least that's how
rcts are supposed to work in future
videos I'll discuss all the ways such
results and subsequent conclusions can
be
biased the major disadvantages of rcts
are that they are expect ensive they are
time consuming and they have ethical
limitations on what can be tested
remember in an RCT investigators are
actively altering What treatments are
being given to a patient which requires
independent ethical oversight usually in
the form of an Institutional review
board or IRB and in the United States
also the
FDA this diagram represents the
hierarchy of evidence there are many
different variations of it but this is
one of the more common according to the
conventional wisdom the most qualitative
forms of evidence have a lower ranking
in terms of importance while the most
quantitative are the most important thus
expert opinion without supporting data
rests on the bottom while a meta
analysis of multiple rcts is at the
top I'm not a fan of this hierarchy I
show it because it's very commonly
presented during lectures on ebm and
it's beneficial to know of its existence
but there are problems with it first
whether intentional or not it
predisposes people to consider any study
in one particular level to be of
superior quality and importance to any
study in any level below it for example
considering meta analyses to always be
preferable to
rcts however that's not necessarily the
case when investigators perform a meta
analysis they combine data from
Individual rcts and if some of those RCT
are biased The Meta analysis may lead to
an erroneous
conclusion also placing expert opinion
at the bottom feels kind of unfair since
expert opinion is typically forged from
a career of examining evidence so even
if one particular opinion doesn't have
specific individual supportive studies
it may still incorporate relevant
Knowledge from collateral evidence
furthermore while personal biases
certainly influence such expert opinions
they absolutely can influence
quantitative studies as well some people
revise this hierarchy to correct for the
undervaluing of expert opinion by
superseding meta analysis with clinical
guidelines clinical guidelines are a
collection of recommendations made by a
group of experts on a particular topic
after they've debated the available
evidence and weighted against their
personal
experiences individual recommendations
within a broader set of guidelines for
the management of a specific condition
are typically great to indicate the
strength of the recommendation and the
quality of the supportive
evidence I think placing clinical
guidelines at the top is generally an
improvement but it can literally take
more than a decade before they are
updated in order to reflect new
research guidelines are also only as
good as those contributing who enter the
process with their own biases and
sometimes a specific agenda and not
every expert appraises the evidence with
equal levels of skepticism this is we
can have multiple sets of clinical
guidelines on the same topic which
disagree in addition to the disagreement
between clinical guidelines the
implementation of ebm in routine
practice has several other notable
limitations first searching for reading
and appraising the primary literature is
timec consuming there is no way that a
physician can apply ebm in a formal
structured way to any more than a small
fraction of the clinical decisions made
over the course of a typical day it's
tempting for a physician to just read
the abstracts of papers from the major
journals and even to just read the
conclusions in the abstracts but doing
so makes way too large an assumption
that the trial is valid and applicable
to their
patients Physicians outside of major
academic centers May lack access to the
medical
literature practicing ebm requires at
least a rudimentary understanding of
Statistics which not all doctors acquire
in medical school which may have been
forgotten after years of
non-use decisions about what clinical
questions get studied and which studies
get published are often not based on
objective logical criteria for example
there's a phenomenon called publication
bias in which journals are more likely
to publish positive clinical trials that
is trials that found a benefit of an
intervention over the control and
researchers are dependent upon
publication success for future grants
and academic promotion
finally many many major trials are
sponsored by the pharmaceutical and
medical device Industries which may have
millions or even billions of dollars
dependent upon their
results all of these conflicts of
interest result in an imperfect veracity
of the medical literature with a bias
towards new and expensive treatments
rather than the boring and less
profitable status
quo that's not to say that there's
rampant overt fraud occurring but such
incentives compromise how confident we
can be that the conclusions of anyone's
study accurately reflect reality and and
many times we don't even have as much as
suboptimal studies on which to base our
opinions there are countless clinical
questions which have NE never been
rigorously studied it's hard to practice
evidence-based medicine in a situation
which has no
evidence but for many Physicians the
most frustrating part about ebm is a
little less Concrete in clinical
practice our decisions are necessarily
dichotomous we either operate on the
patient or we don't a medication is
either started or it's not and thus it
would be convenient if the clinical
evidence was equally dichotomous an
intervention either works or it doesn't
a particular study is either valid or
it's not unfortunately clinical evidence
is rarely if ever black or white there
may be supportive evidence that a
particular intervention works but not
definitive proof
a study may be biased but it does not
necessarily mean the results are
completely invalid and thus even if one
knows the best available evidence
practicing ebm can still be infused with
a great deal of
uncertainty this can make some doctors
uncomfortable because they believe the
scientific evidence we use in medicine
should be exact precise and
reproducible this is implicit in the
behavior of doctors who use studies to
dictate treatment decisions but without
ever digging below the surface
to see how methodologically sound those
studies were or how well they actually
apply to the patient in
question and that brings us around again
to what ebm is really about it's not
just the evidence it's applying the
evidence together with clinical
experience and patient values in or in
order to arrive at an informed and
shared decision with your patient even
if the relevant evidence was perfectly
quantifiable neither your clinical
experience nor your patient value values
are part of the beauty and joy of
practicing medicine comes from the fact
that it cannot be reduced down to a set
of optimized
algorithms Instinct judgment and
communication all play key
roles however we still need the skills
to appraise the quality of the evidence
we're using even if we can't perfectly
measure and quantify its validity
otherwise we'd be practicing medicine
completely in the dark operating solely
on faith that what we are doing is
helping our
patients so that's my brief introduction
to ebm and some of its relevant
terminology and Concepts if you found it
to be helpful please remember to like
and share it and be on the lookout for
more videos in this series to come
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