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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.
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