Search for Evidence;
Evidence Based Medicine
Prepared By: Nadia Masoud
The Medical Librarian
Physicians “NEED” EBM, WHY?
In order to take a proper clinical
decisions, physicians should keep up-todate with the Medical Literature.
To keep themselves updated, physicians
need to read at least 6-8 hours daily.
These hours will be added to the busy
schedule and work load they have daily.
Physicians “NEED” EBM, WHY?
• Need for valid information daily on Diagnosis,
treatment, prognosis and prevention
• Inadequate traditional sources:
Outdated, too voluminous to be practical”
(Textbooks)
Frequently wrong (Expert opinions)
Ineffective (Didactics/CME)
Too overwhelming in volume and variable
in validity (Medical Journals)
EBM Founding Father
Prof. Archibald Cochrane a
British medical epidemiologist
is the Founding Father of the
Evidence Based Medicine
Concept.
“The Cochrane Collaboration”,
the main source for EBM, was
named after him.
Evidence Based Medicine (EBM)
Evidence-based medicine is
the integration of best research
evidence with clinical
expertise and patient values
Sackett DL, Straus SE, Richardson WS,
Rosenberg W, and Haynes RB. EvidenceBased Medicine: How to Practice and
Teach EBM, 2nd Ed, Churchill Livingstone,
London, 2000
Evidence Based Medicine
• Basis of Evidence-based care involves the integration of the
best research evidence with clinical expertise and patient
values.
Best Clinical Evidence
Clinical Experience
Patient’s Needs/ Preferences
The Evidence Based Cycle
•
•
•
•
•
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Identify and define the problem
Formulate a focused clinical question
Identify the appropriate resources
Search for valid and relevant information
Critical appraisal
Implement in practice
Types of Clinical Questions
• Background Questions ask for general knowledge about
a disease, disease process or clinical circumstances.
• Background Questions are those questions which have
been answered in the past and are now part of the “fiber
of medicine”
• Ask They generally ask "who, what, when, why, where or
how" about a single disease, drug, intervention or
concept.
• You can find a helpful background information particular
subject by searching Encyclopedias, dictionaries,
textbooks, thesauri, ..etc. Bibliographies at the end of
articles lead you to other books and articles on your topic,
which might be very helpful.
Types of Clinical Questions
• Foreground Questions The foreground questions
are the base of the EBM Search. They are more
difficult to answer than background questions
because they require sources that provide a wide
range of knowledge and look for specific patient
cases or problems.
Searching the Online Databases
• Choose the appropriate database
• Consult at least two databases to
prevent missing a significant piece of
work on the subject
• When using a new database, familiarize
yourself with its language by using the
online help
Develop a Search Strategy
There are seven steps to be considered for applying the
EBM principles and responding to the clinical
inquiries.
• Receive and analyze the clinical question by using
the PICO method
• Expand your background, gather pertinent
background information
• Classify the clinical question into a category
(therapy, diagnosis, etiology, prognosis)
• Search for the information in the best resources
• Evaluate literature for accuracy and relevance
• Formulate a response
• Communicate information and follow up(1)
The EBM Process
•
•
•
•
•
Assess your patient
Ask clinical questions
Acquire the best evidence
Appraise the evidence
Apply the evidence to patient
care
ASK A Clinical Question
• Formulate a well-built clinical questions.
• In practice, well-built clinical questions
usually contain four elements abbreviated in
PICO Format
• P - Patient / problem : Identify the
problem of the patient
• I - Intervention of Interest (such as
a drug or test)
• C – Comparison / the Comparison
Intervention
• O – Outcome / the Intended Outcome
• Patient / Population – who and what?
• Intervention – how?
• Comparison (if appropriate) – what is the main
alternative?
• Outcome – what are you hoping to accomplish,
measure, improve, affect?
•
•
•
•
P = Patient/Problem/Population: Ask “how would I describe a group of
patients similar to mine?” Balance precision with brevity
I = Intervention: Ask “which main intervention am I considering?” (cause,
prognostic factor, treatment, etc..)
C = Comparison/Control: Ask “which is the main alternative to compare
with the intervention?” again, be specific
O = Outcome: Ask “what can I hope to accomplish?” or “what could this
exposure really affect?” again, be specific.
Types of Research Studies
• 1-Randomized controlled trial: (answers therapy, prevention
questions)
Randomization avoids selection bias. Clinical trials that involve one
test treatment and one control treatment, concurrent enrollment and
follow up of the test-and control treated groups, and in which the
treatments to be administered are selected by a random process.
Types of Research Studies
• 2-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. 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.
Types of Research Studies
• 3-Case control study: (answers prognosis, etiology, prevention
questions)
Case control studies are studies that 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 and 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.
Search for the Best Study
Type of Question
Best Type of Study to Search For
Therapy
RCT>cohort > case control > case series
Diagnosis
Prospective, blind comparison to a gold
standard
Etiology/Harm
RCT > cohort > case control > case series
Prognosis
Cohort study > case control > case series
Prevention
Clinical Exam
Cost
RCT>cohort study > case control > case
series
Prospective, blind comparison to gold
standard
Economic analysis
Acquire the Best Evidence
• Online databases are the most important sources for
evidence retrieval.
• The best method to search for evidence is by using the
“4S’ hierarchical structure of Evidence Databases, which
consist
• Systems; Online resources provide summary reviews
of the relevant medical information on specific
clinical cases.
• Synopses; which are evidence based summaries
prepared from original research
• Synthesis; Systematic Reviews can be found through
the Cochrane Library
• Studies; Research published in non-filtered databases
“4S’ Hierarchical Structure of the Online
Databases to be Searched for EBM
EBM Search Protocol Pyramid
Navigating the Maze: Information Mastery: How to lower the work of Your
Information Searches: An Overview, Health Sciences Library, University of Virginia
Searching Tips, to Recall Relevant Evidence
Search Strategy to build the Inquiry Strings should be
implemented.
They include;
• Defining appropriate Keywords from the clinical
question, Use Medical Subject Headings (MeSH) if
required;
• Considering Synonyms and related terms;
• Selecting the most relevant databases;
• Combining keywords with Boolean Operators;
• Considering the “Phrase Searching” and
Truncations.
Boolean Searching
Use Boolean Operators to combine search terms.
These are the most common connectors:
• “And” : To narrow your search. All terms must
appear in results
• “OR” : To broaden your search. Either term should
appear in results
• “Not” : To narrow your search by excluding
specific terms.
• “Adj” : Search for terms that appear together
Using AND, OR, NOT, and ADJ to create logical search
statements is also known as Boolean searching ,
Boolean Operators.
Phrase Searching
 You can narrow your search by using a “Phrase Search”
instead of keywords.
 Put your phrase between Quotations (“ “)
Examples
“Evidence Based Medicine”
“Point of Care Testing”
“Physical Therapy”
Truncation
 To obtain more results and broaden your search, Truncate / Stem the word
to its root.
 Truncation means shortening a search term by adding a symbol to the root
of a word, to retrieve its variant endings
Examples
 Search for “child*” retrieves documents for child,
children, childhood, childbirth, …etc.
 The most used Truncation Symbol is the Asterisk (*)
Tips for Smart Searching




Always be as precise as possible when selecting keywords
that describe your topic
Check your spelling
Use acronyms if available
(WHO – World Health Organization )
Consider differences between American and British
spelling
(Hematology / Haematology – Pediatrics / Paediatrics)
Clinical Case
• Jeff, a smoker of more than 30 years, has talked about
giving up smoking. He has tried unsuccessfully to quit in
the past. He has heard through a friend that acupuncture
was successful. Should he try it? Other interventions that
you know of include nicotine replacement therapy and
antidepressants.
• Clinical question
• In people who smoke is acupuncture compared to
nicotine replacement therapy or antidepressants
effective treatment for smoking cessation.
PICO
Population
Smoker
Intervention
Acupuncture
Comparison
Nicotine replacement therapy OR
antidepressants
Outcome
Smoking cessation
Clinical Question
Question Analysis / PICO Format
Patient / Population :
Intervention
Comparison
Outcome
:
:
:
Patients with chronic
heart failure
Chocolate intake
No chocolate intake
blood pressure
Cochrane Library
Search #1 : "heart failure" or "cardiovascular
disease*“
Search #2 : "high blood pressure" or hypertension
Search #3 : chocolate or cocoa
Search #4 : 1 and 2 and 3
Clinical Question
Is the land-based therapeutic exercise beneficial for people with knee OA in terms of
reduced joint pain or improved physical function. ?
Question Analysis / PICO Format
Patient / Population :
Intervention
Comparison
Outcome
:
Adults, Knee Osteoarthritis
:
Land-Based Therapeutic Exercise
:
Drug Therapy
Reduce Pain / Improved Physical Function
Search String
knee$ and (osteoarthritis or OA) and (exercise or physiotherapy or
"physical therapy") and ("reduc$ pain" or comfort$)
Appraise the Evidence
Critical Appraisal is the process of carefully and
systematically examining research evidence to
judge its trustworthiness, its value and relevance in
a particular context.
The purpose of the critical appraisal is to determine
whether;
• Research evidence is accurate and free of
known or unknown bias,
• Evidence results are acceptable and provide
the answer to the question raised
• How confidently can the evidence be applied
to the practice
Critical Appraisal Process
Assess the Validity
Are the results valid?
A crucial question in the critical appraisal process.
The recalled / retrieved evidence should be
examined for;
• Well Built PICO Question
• Randomization for selecting participating
patients to eliminate Bias
• Research study should be blinded, or doubleblinded when possible.
• Study groups must be treated equally
• ensure that patients who started the trial are
accounted for until the end.
Critical Appraisal Process
What are the Results?
• What are the Results?
Once the validity of the study is ensured,
statistical analysis should be performed on
the retrieved study results to check the
Values .
• Each study type, either Therapy or
Diagnosis, etc. has its measures to
calculate.
• The findings / Calculation Results should
fall within the range of True Values.
Apply on the Patient
• Decision should be taken whether to apply
the evidence on the patient or not.
• Physician should ask the following questions before
Applying the evidence;
• Is my patient so different from those in the
study?
• Is the treatment available in my setting OR Is
the healthcare system willing to fund it
• What are the alternatives available?
• What are the side effects of the intervention?
• Are the outcomes appropriate to my patient?
Cochrane Group Lists
New Example
In post-menopausal women, does hormone replacement treatment
therapy prevent osteoporosis
Terms
Osteoporosis / Bone Density / Bone Mass
Post-menopaus$ / menopaus$ / women
Hormone Replacement Therapy / HRT
Search String
Osteoporosis and menopaus$ and (“hormone treatment
therapy” or hrt)
Should you have any inquiries, please send
an e-mail to nadia@sharjah.ac.ae
OR
Contact the Medical Library at 065057176 / 06-5057176
Thank You
THANK YOU