EVIDENCE BASED MEDICINE

for Beginners

EVIDENCE BASED MEDICINE

for Beginners

Maria Fidelis Manalo, MD, Msc Epidemiology

Department of Community & Family Medicine

FEU-NRMF Medical Center

Philippines

Maria Fidelis Manalo, MD, Msc Epidemiology

Department of Community & Family Medicine

FEU-NRMF Medical Center

Philippines

Evidence-Based Medicine Definition

Evidence-Based Medicine Definition

“the conscientious, explicit and judicious use of current best evidence in making decisions about the care of the individual patient”

David Sackett

“the conscientious, explicit and judicious use of current best evidence in making decisions about the care of the individual patient”

David Sackett

EBMHistorical Evolution

EBMHistorical Evolution

Has roots going back to 19th c.  Recently broadened interest due to information

explosion that increased dramatically in the last decade.

Has become more formalized that have enabled practitioners to approach medical problems and evaluate medical literature with greater consistency and to deal with massive amounts of medical information via a qualitative approach.

Has roots going back to 19th c.  Recently broadened interest due to information

explosion that increased dramatically in the last decade.

Has become more formalized that have enabled practitioners to approach medical problems and evaluate medical literature with greater consistency and to deal with massive amounts of medical information via a qualitative approach.

EBMUsefulness

EBMUsefulness

Instead of routinely reviewing the contents of dozens of journals for interesting articles, EBM suggests that you target your reading to issues related to specific patient problems as encountered. 

This makes EBM a life-long self-directed and problem-based learning process.

Instead of routinely reviewing the contents of dozens of journals for interesting articles, EBM suggests that you target your reading to issues related to specific patient problems as encountered. 

This makes EBM a life-long self-directed and problem-based learning process.

Misapprehensions & Misinterpretations about EBM

Misapprehensions & Misinterpretations about EBM

X 1) Evidence-based medicine ignores clinical experience and clinical intuition.

X 2) Understanding of basic investigation and pathophysiology plays no part in evidence-based medicine.

X 3) Evidence-based medicine ignores standard aspects of clinical training such as the physical examination.

X 1) Evidence-based medicine ignores clinical experience and clinical intuition.

X 2) Understanding of basic investigation and pathophysiology plays no part in evidence-based medicine.

X 3) Evidence-based medicine ignores standard aspects of clinical training such as the physical examination.

Types of QuestionsTypes of

Questions

Asked for general knowledge about a disorder 

Has two essentials components:– a question root ( who, what, where,

how, why) with a verb– a disorder

Asked for general knowledge about a disorder 

Has two essentials components:– a question root ( who, what, where,

how, why) with a verb– a disorder

(1) Background Questions(1) Background Questions

Background QuestionsBackground Questions

Textbooks answer background questions, they contain collected & synthesized wisdom for topics that do not change often. 

Not all topics are covered, easy to use, relatively inexpensive and can be opinion-based rather than evidence-based, written by experts in their fields.

Textbooks answer background questions, they contain collected & synthesized wisdom for topics that do not change often. 

Not all topics are covered, easy to use, relatively inexpensive and can be opinion-based rather than evidence-based, written by experts in their fields.

(2) Foreground Questions(2) Foreground Questions

Asked for specific knowledge about managing patients with a disorder

It has 4 components (PICO analysis):

P - Patient/Population

I - Intervention

C - Comparison

O - Outcome

 

Basis of Evidence-based care involves the integration of the best research evidence with clinical expertise and patient values.            

Basis of Evidence-based care involves the integration of the best research evidence with clinical expertise and patient values.            

Patient’s Needs/Preferences

Clinical Experience

Best Clinical Evidence

Novice Expert Searcher   Searcher

At all stages you ask both kinds of questions, but as experience increases the foreground questions increase. 

It is essential that you understand the background question before attempting to answer the foreground ones.

 

Background Information

Foreground Information

EBM Principles EBM Principles

1.  Construct a well-built clinical question

and classify it into one category (therapy,

diagnosis, etiology or prognosis)

2.  Find the evidence in health care literature

3.  Critically appraise or formally evaluate

for validity and usefulness

4.  Integrate the evidence with patient

factors to carry out the decision

5.  Evaluate the whole process

1.  Construct a well-built clinical question

and classify it into one category (therapy,

diagnosis, etiology or prognosis)

2.  Find the evidence in health care literature

3.  Critically appraise or formally evaluate

for validity and usefulness

4.  Integrate the evidence with patient

factors to carry out the decision

5.  Evaluate the whole process

PICO ANALYSISPICO ANALYSIS

Before attempting to search for the evidence in the literature, construct a well-built or clearly structured question that could be broken into the following four parts

Before attempting to search for the evidence in the literature, construct a well-built or clearly structured question that could be broken into the following four parts

(1) Patient /Population (1) Patient /Population

What is the primary problem, disease or co-existing conditions? 

On what groups do you want information?  

How would you describe a group of patients similar to the one in question?  

Sometimes age or sex of a patient may be relevant and should be included.  – Example: post-menopausal women with

hypertension

What is the primary problem, disease or co-existing conditions? 

On what groups do you want information?  

How would you describe a group of patients similar to the one in question?  

Sometimes age or sex of a patient may be relevant and should be included.  – Example: post-menopausal women with

hypertension

(2) Intervention (2) Intervention

What medical event do you want to study the effect of?  

Which main intervention are you considering, prescribing a drug, ordering a test, ordering surgery?. . . . – Example: ERT

What medical event do you want to study the effect of?  

Which main intervention are you considering, prescribing a drug, ordering a test, ordering surgery?. . . . – Example: ERT

(3) Comparison (3) Comparison

Compared to what?   Better or worse than no intervention at all

or than another intervention?   What is the main alternative to compare

with the intervention, are you trying to decide between two drugs, a drug and a placebo, or two diagnostic tests? 

Sometimes there is no comparison.   - Example: no ERT

Compared to what?   Better or worse than no intervention at all

or than another intervention?   What is the main alternative to compare

with the intervention, are you trying to decide between two drugs, a drug and a placebo, or two diagnostic tests? 

Sometimes there is no comparison.   - Example: no ERT

(4) Outcome (4) Outcome

What is the effect of the intervention?  What do you hope to accomplish,

measure, improve, or affect with this intervention? 

What are you trying to do for the patient, relieve or eliminate the symptoms, reduce side effects, reduce cost? .. .– Example: improve quality of life

What is the effect of the intervention?  What do you hope to accomplish,

measure, improve, or affect with this intervention? 

What are you trying to do for the patient, relieve or eliminate the symptoms, reduce side effects, reduce cost? .. .– Example: improve quality of life

What makes a clinical question well built?

What makes a clinical question well built?

Question should be directly relevant to the problem at hand.

Question should be phrased to facilitate searching for a precise answer.

Asking a well-built question, like many clinical skills, needs practice.

Question should be directly relevant to the problem at hand.

Question should be phrased to facilitate searching for a precise answer.

Asking a well-built question, like many clinical skills, needs practice.

After constructing the PICO analysis, determine the category of the question. 

There are the four categories of EBM questions

After constructing the PICO analysis, determine the category of the question. 

There are the four categories of EBM questions

Categories of EBM Questions

Categories of EBM Questions

Solves questions about which treatment to administer, and what might be the outcome of different treatment options. 

For most therapy questions one may want to look for the best evidence namely a randomized controlled study, and if the study can be a double blind, so much the better. 

- Example: find the evidence for the use of anticoagulants in patients with atrial fibrillation

Solves questions about which treatment to administer, and what might be the outcome of different treatment options. 

For most therapy questions one may want to look for the best evidence namely a randomized controlled study, and if the study can be a double blind, so much the better. 

- Example: find the evidence for the use of anticoagulants in patients with atrial fibrillation

1) Therapy 1) Therapy

Solves questions about degree to which a test is reliable and clinically useful, to decide whether the patient would benefit from it

Most articles compare result of a certain diagnostic test with that of a standard test regarded as being a "gold standard". 

- Example: search for the best diagnostic test for

Alzheimer's disease  

Solves questions about degree to which a test is reliable and clinically useful, to decide whether the patient would benefit from it

Most articles compare result of a certain diagnostic test with that of a standard test regarded as being a "gold standard". 

- Example: search for the best diagnostic test for

Alzheimer's disease  

2) Diagnosis2) Diagnosis

Solves problems about the relationship between a disease and a possible cause

- Example: find out if a diet rich in saturated fats

increases the risk of heart disease, and if so by

how much

Solves problems about the relationship between a disease and a possible cause

- Example: find out if a diet rich in saturated fats

increases the risk of heart disease, and if so by

how much

3) Etiology3) Etiology

Answers questions about a patient's future health, life span and quality of life in the event one chooses a particular treatment option

- Example: find how would the quality of life change for a patient who undergoes surgery for prostate cancer 

The next step would be to determine the best study design needed to answer the clinical question.

Answers questions about a patient's future health, life span and quality of life in the event one chooses a particular treatment option

- Example: find how would the quality of life change for a patient who undergoes surgery for prostate cancer 

The next step would be to determine the best study design needed to answer the clinical question.

4) Prognosis4) Prognosis

Types of Research StudiesTypes of Research Studies

Certain study designs are superior to others when answering particular questions.

– RCT are considered the best for addressing questions about therapy.

– Etiology questions may be addressed by case-control & cohort studies. 

Other aspects relevant to study design include placebo comparison group and follow-up.

Certain study designs are superior to others when answering particular questions.

– RCT are considered the best for addressing questions about therapy.

– Etiology questions may be addressed by case-control & cohort studies. 

Other aspects relevant to study design include placebo comparison group and follow-up.

Answers therapy, prevention questions

Randomization avoids selection bias

Answers therapy, prevention questions

Randomization avoids selection bias

1) Randomized Controlled Trial (RCT)

1) Randomized Controlled Trial (RCT)

2) Cohort study2) Cohort study Answers prognosis, etiology, prevention questions Cohorts are defined populations that, as a whole, are

followed in an attempt to determine distinguishing subgroup characteristics.  

Researchers identify and compare two groups over a period of time. 

Answers prognosis, etiology, prevention questions Cohorts are defined populations that, as a whole, are

followed in an attempt to determine distinguishing subgroup characteristics.  

Researchers identify and compare two groups over a period of time. 

At the start of the study, one of the groups has a particular condition or receives a particular treatment, and the other does not. 

At the end of a certain amount of time, researchers compare the two groups to see how they did. 

At the start of the study, one of the groups has a particular condition or receives a particular treatment, and the other does not. 

At the end of a certain amount of time, researchers compare the two groups to see how they did. 

2) Cohort study2) Cohort study

3) Case Control study3) Case Control study

Answers prognosis, etiology, prevention questions

Identifies patients who already have the outcome of interest and control patients without that outcome, and look back to see if they had the exposure of interest or not.  

Answers prognosis, etiology, prevention questions

Identifies patients who already have the outcome of interest and control patients without that outcome, and look back to see if they had the exposure of interest or not.  

4) Case series & Case Reports 

4) Case series & Case Reports 

Answers prognosis, etiology, prevention questions

Consist either of collections of reports on the treatment of individual patients, or of reports on a single patient.

Answers prognosis, etiology, prevention questions

Consist either of collections of reports on the treatment of individual patients, or of reports on a single patient.