Evidence Based Medicine
Dr. Mansour AlZahrani
SB-FM,ABFM,MRCGP[INT]
Consultant and Assistant professor of
Family Medicine
Objectives
• Know the definition of evidence based
medicine.
• Discuss steps of evidence-based medicine.
• Discuss types of the studies.
• Define Randomized control, diagnostic,
meta-analysis & systematic review, cohort
and case control studies.
Definition
Evidence-based medicine requires the
integration of the best research evidence with
our clinical expertise and our patient’s unique
values and circumstances.
Patient
Values
Straus SE, Richardson WS, Glasziou P,
Haynes RB. Evidence-based medicine: how
to practice and teach EBM 3d ed. London:
Churchill Livingstone, 2005
EBM
Best
research
evidence
Clinical
Expertise
Why is EBM important?
• Physician is taking a decision all the time.
• Physicians asked 2 questions for every 3 patients.
• Only 30% of physicians' information needs were met during
the patient visit, usually by a colleague.
• EBM can confirm your plan but it can change it totally.
• Is EBM a "cook book medicine“ ?!!
STEPS IN EVIDENCE BASED RESEARCH
1.
2.
Asking answerable questions
Finding the best evidence
3.
4.
5.
Critically appraising the evidence
Applying a decision
Evaluation
Heneghan C, Badenoch D. Evidence-based medicine toolkit. 2d ed. Malden, MA:
Blackwell, 2007
The Answerable Question
STEP 1
• Asking answerable questions – focused,
searchable, clinical
• PICO
• Patient, Problem, Population (subjects)
• Intervention or therapy
• Comparison, Control
• Outcome (results)
Can You Identify PICO?
• In children under 6 months, how does
sleeping on back compared to sleeping on
the stomach in terms of risk of SIDS?
• In children under 6 months (P), how does
sleeping on back (I) compared to sleeping on
the stomach (C) in terms of risk of SIDS (O)?
STEP 2
• Finding the best evidence with which to
answer the question through structured searches and
understanding the literature
Just do it!!
• Um Ahmed is a new patient in your clinic. She is 70 year old
and has a history of congestive heart failure brought on by
several myocardial infarctions.
• She has been hospitalized twice within the last 6 months for
worsening of heart failure. Her medications (enalapril, aspirin
and simvastatin).
• You think she should also be taking digoxin but you are not
certain if this will help keep her out of the hospitalization. You
decide to research this question before her next visit.
Step 1
• PICO designed question.
• In elderly patients with congestive heart failure, is digoxin
effective in reducing the need for hospitalization?
Types of studies
Medline
• The world’s largest biomedical database
• Over 5,000 journals indexed, with worldwide coverage
• Covers all aspects of biosciences and healthcare
• Database of 19+ million journal citations, 1950 to the
present
• 90% are in English ; 79% have abstracts
• The primary component of PubMed
So What Is PubMed?
• PubMed is a tool to search:
• MEDLINE (1950 to present)
• Produced by NCBI
• National Center for Biotechnology Information, part of NLM
• Accessible worldwide on the Web at no charge
Accessing PubMed
• Directly at: http://pubmed.gov
• Or, National Library of Medicine’s homepage:
http://www.nlm.nih.gov
Definitions
• Case-control study:
A study which involves identifying patients who have the outcome of
interest (cases) and patients without the same outcome (controls),
and looking back to see if they had the exposure of interest.
• Case series
A report on a series of patients with an outcome of interest. No
control group is involved.
• Cohort Study
Involves identification of two groups (cohorts) of patients, one which
received the exposure of interest, and one which did not, and
following these cohorts forward for the outcome of interest.
• Randomized control clinical trial (RCT)
Participants are randomly allocated into an experimental group or a
control group and followed over time for the variables/outcomes of
interest.
• Systematic review
A summary of the medical literature that uses explicit methods to
perform a comprehensive literature search and critical appraisal of
individual studies and that uses appropriate statistical techniques to
combine these valid studies.
• Meta-analysis
A systematic review that uses quantitative methods to synthesize and
summarize the results.