An Introduction to Evidence Based Medicine

Summary

This 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

00:00

📚 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.

05:02

🔍 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.

10:03

🧪 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.

Keywords

💡Evidence-Based Medicine (EBM)

Evidence-Based Medicine (EBM) is the integration of the best research evidence with clinical expertise and patient values in medical decision-making. In the video, EBM is emphasized as more than just memorizing landmark studies. Instead, it involves critically appraising and applying evidence in the context of a patient's unique situation. For instance, using a framework like the 'five A's' (assess, ask, acquire, appraise, and apply) ensures that decisions are grounded in solid evidence.

💡Randomized Controlled Trial (RCT)

A Randomized Controlled Trial (RCT) is a type of clinical study where participants are randomly assigned to either a treatment or control group to evaluate the effects of an intervention. RCTs are often highlighted as the gold standard in EBM because they minimize bias and allow for the assessment of a single variable's impact. In the video, the explanation of RCTs includes important aspects such as randomization, control groups, and blinding, emphasizing their reliability in testing new treatments.

💡Meta-analysis

A Meta-analysis is a quantitative review of multiple studies that investigates similar research questions. By combining data from several trials, it can produce a more powerful and comprehensive conclusion than individual studies might offer. The video describes how meta-analyses can detect patterns or effects that smaller studies may miss, but also warns of potential biases if the included studies are flawed.

💡Clinical Guidelines

Clinical Guidelines are expert-derived recommendations for the management of specific conditions based on a combination of research evidence and professional consensus. In the video, clinical guidelines are positioned as a potentially superior alternative to the traditional evidence hierarchy because they incorporate expert judgment and are designed to be practical. However, they are also subject to bias and may lag behind the latest research.

💡Publication Bias

Publication Bias refers to the tendency for positive results to be published more frequently than negative or inconclusive findings. This can distort the medical literature and give a misleading impression of a treatment's efficacy. The video mentions publication bias as a significant challenge in EBM because it can result in the overemphasis of new, often expensive treatments while downplaying more conservative approaches.

💡Cohort Study

A Cohort Study is a type of observational study where a group of people (a cohort) is followed over time to determine how certain exposures or interventions affect outcomes. The video highlights cohort studies as one form of observational research, where investigators passively monitor patients without intervening, offering insights into natural disease progression or treatment effects in a real-world setting.

💡Blinding

Blinding in a clinical trial refers to concealing which participants receive the treatment and which receive the control or placebo. Double-blinding, where neither the patient nor the clinician knows who is in which group, helps prevent bias in assessing outcomes. The video explains that well-designed RCTs are often double-blinded to maintain objectivity and ensure that the treatment's effectiveness is evaluated without influence from the participants or researchers.

💡Case-Control Study

A Case-Control Study is a type of observational study where individuals with a certain condition (cases) are compared to those without the condition (controls) to identify factors that might contribute to the condition's development. In the video, case-control studies are mentioned as a common observational study design that, while useful, is more prone to bias than RCTs due to the lack of randomization.

💡PICO Framework

The PICO Framework is a tool used to structure clinical questions in EBM. It stands for Patient, Intervention, Comparison, and Outcome. For example, in the video, a PICO question might ask whether a specific drug (intervention) is more effective than a placebo (comparison) in reducing COPD exacerbations (outcome) in adults with advanced COPD (patient). This framework helps guide the search for relevant clinical evidence.

💡Hierarchies of Evidence

Hierarchies of Evidence refer to the ranking of different types of studies based on their reliability and validity, with randomized controlled trials and meta-analyses often at the top. In the video, the traditional hierarchy is critiqued for undervaluing expert opinion and clinical judgment, which are essential when evidence is incomplete or conflicting. It is suggested that clinical guidelines may be a better way to synthesize evidence and expert consensus.

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