Basics of Evidence Based Medicine system

1. It is astonishing with how little reading a
doctor may practice medicine, but it is not
astonishing, how badly he may do it.
- Butler, "Equanimitas", 1901

2. Clinical PracticeClinical PracticeClinical PracticeClinical Practice
In
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3. How do we use the clinical evidence/
How do we answer “What works?” (Berg)
A. Trust Me
• Dr. Smith: So which statin would you
recommend?
• Dr. Jones: Atorvastatin is the drug of choice.
Translation:
Does it work?
It does if I say so.
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4. How do we use the clinical evidence/
How do we answer “What works?” (Berg)
B. Deferral to Authority
• Dr. Smith: So which statin would you recommend?
• Dr. Jones: I prefer atorvastatin, and the last time I
sent someone over to the Lipid Clinic, that was Dr.
Doe’s recommendation as well.
Translation:
Does it work?
It does if Dr. Expert says so.
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5. How do we use the clinical evidence/
How do we answer “What works?” (Berg)
C. In My Experience
• Dr. Smith: So which statin would you
recommend?
• Dr. Jones: I don’t really like any of them. I have
had good experience with diet and
cholestyramine and never prescribe HMG-CoA
reductase inhibitors.
Translation:
Does it work?
It does work ? It does seem to.
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6. How do we use the clinical evidence/
How do we answer “What works?” (Berg)
D. Everyone Else is Doing It
• Dr. Smith: So I have this 55-year old man in for a
complete physical, and he’s asking about screening for
prostate cancer.
• Dr. Jones: (Medical Director): Make sure you do a
digital rectal examination and get a PSA. We’ll get sued
if you don’t and he develops prostate cancer, because
screening is the standard in our community.
Translation:
Does it work?
It does work ? ? It does if everyone agrees that it does.
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7. Is there a better way to find and use
clinical evidence?
Evidence - Based Medicine !Evidence - Based Medicine !
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8. E.B.M. - History
Evidence-based medicine originated in
McMaster University, Ontario, Canada;
in the 1980s where a group of
researchers wanted to bring about a
change in approach of medical practice
from one that had its
foundation in
personal experience
to one based on
scientific evidence.
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9. What is evidence-based medicine?What is evidence-based medicine?
“Evidence-based medicine is the integration
of
best research evidence
with
clinical expertise
and
patient values”
- Sackett, et al 2001
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10. Purposes of Evidence Based
Medicine
 Keeping Your Skills up to Date
 Saving Time
 Saving Lives
 Supplementing Clinical Judgment
Evidence Based Medicine provides us with the tools we need to find
important new medical research quickly and easily,
and to work out its implications for our practice.
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11. Keeping Your Skills up to Date
"A well-used library is one of the few
antidotes a
general practitioner has to the
premature senility that is liable to
overtake him.”
- Butler, "Equanimitas", 1901
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12. Keeping Your Skills up to Date
In the years after you
graduate, two things
will happen:
 Your memory of what
you learned in
medical school will
lose its freshness
 New treatment
methods will be found
that they never taught
you about in school
because they didn't
exist.
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13. Saving Time
The total amount of knowledge out there is far greater and often more reliable
than the clinical experience of one physician or even a group of experts.
You no longer need to read through masses of journals in order to take
advantage of it. It is no longer your job to know everything, even in your
chosen specialty.
It IS your job to be able to find the information as and when you and your patients need it.
Journals on Ageing in 1974 : 28 Journals on Ageing in 1994 : 95
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14. Saving Lives
A detailed
and exact
knowledge of
the outcomes
of different
treatments,
derived from
the research,
can often
save lives.
e.g. -- the problem of whether to perform an endarterectomy on a newly symptomatic
patient with severe stenosis. The benefit of surgery in reducing the risk of a major
stroke or fatality is summed up in that you need only treat 11 patients, on average, to
prevent a major stroke or fatality
(L. Goldstein et al, 1995):
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15. Supplementing Clinical Judgment
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16. 1. Formulate an answerable question
2. Track down the best evidence
3. Critically appraise the evidence
4. Integrate with clinical expertise and
patient values
Elements of evidence-based medicineElements of evidence-based medicine
Information “pull” Steps in EBM process
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17. Formulating an Answerable
Clinical Question
P Patient or
population
Describes patient (age, sex, race,
past medical history, etc.)
A 50 year old woman with a
family history of breast cancer
I Intervention What happens or is to be done;
treatment, diagnostic test, exposure,
screening
Hormone replacement therapy
C Comparison Compared to what? Nothing,
placebo, gold standard, another
intervention
Placebo
O Outcomes
(preferably
clinical)
What is the effect of the intervention?
(Be specific: mortality after a
particular time period,
hospitalizations).
Prevention of Alzheimer's
Disease
AMONG 50-year old women with a family history of breast cancer DOES hormone replacement therapy
AS COMPARED TO placebo reduce the risk of Alzheimer's Disease?

18. Formulating an Answerable
Clinical Question
• Example 1
In Preterm infant born < 32 weeks
gestation does exogenous surfactant
therapy compared to no therapy –
reduce the mortality?
Formulate an
answerable
question
Track down the
best evidence
Critically appraise
the evidence
Integrate with
clinical expertise
and patient values
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19. Formulating an Answerable
Clinical Question
Example 2:
“the first sign of hyperkalaemia is death”
• An anxious laboratory technician phoned about a
potassium of 7.3 mmol/l (Ref Range 3.5-5.0)
found on a routine blood test of a 50 year old
woman.
• I arranged an urgent repeat of the electrolytes
(to rule out a spurious elevation) and an ECG.
• The latter was reassuringly normal, but left me
asking:
Does a normal ECG rule out a serious elevation
of potassium?
Formulate an
answerable
question
Track down the
best evidence
Critically appraise
the evidence
Integrate with
clinical expertise
and patient values
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20. Formulating an Answerable
Clinical Question
1. The question
• Does a normal ECG rule out a serious
elevation of potassium?
• Population - In suspected
hyperkalemia
• Indicator - does a normal ECG
• Comparator -
• Outcome - rule out hyperkalemia?
Formulate an
answerable
question
Track down the
best evidence
Critically appraise
the evidence
Integrate with
clinical expertise
and patient values
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21. Tracking the evidence
JASPA*
(Journal associated score of personal angst)
Formulate an
answerable
question
Track down the
best evidence
Critically appraise
the evidence
Integrate with
clinical expertise
and patient values
J: Are you ambivalent about renewing your JOURNAL
subscriptions?
A: Do you feel ANGER towards prolific authors?
S: Do you ever use journals to help you SLEEP?
P: Are you surrounded by PILES of PERIODICALS?
A: Do you feel ANXIOUS when journals arrive?
• 0 (?liar)
• 1-3 (normal range)
• >3 (sick; at risk for polythenia
gravis
and related conditions)
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22. Earlier
Great dearth of Information
Since 1987, when the first publication on the properties of the Lactobacillus GG was
done, there have been over 200 publications in peer-reviewed scientific journals.
Trackingtheevidence
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23. Tracking the evidence
Formulate an
answerable
question
Track down the
best evidence
Critically appraise
the evidence
Integrate with
clinical expertise
and patient values
• Over 2 million articles published
every year in around 20,000
journals
• A doctor has to refer 30 medical
journals a week to keep abreast in
his specialty - which is almost
impossible considering the busy
schedules.
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24. Review the World Literature Fortnightly*
0
500000
1000000
1500000
2000000
2500000
Trials MEDLINE BioMedical
MedicalArticlesperYear
5,000?
per day
1,400
per day55 per
day
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25. Tracking the evidence
Formulate an
answerable
question
Track down the
best evidence
Critically appraise
the evidence
Integrate with
clinical expertise
and patient values
 a) Medical Databases
 b) Search engines
 c) Medical news services
 d) Medical journals and
textbooks
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26. Tracking the evidence
Formulate an
answerable
question
Track down the
best evidence
Critically appraise
the evidence
Integrate with
clinical expertise
and patient values
 a) Medical Databases:
 1. Best Evidence
 2. Cochrane Library
http://www.cochrane.org
 3. Medline
http://www.ncbi.nlm.nih.gov/entrez/q
uery.fcgi?db=PubMed
 3. TRIP Database
http://www.update-software.com/
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27. Tracking the evidence
Formulate an
answerable
question
Track down the
best evidence
Critically appraise
the evidence
Integrate with
clinical expertise
and patient values
 b) Search engines
 Google www.google.com
 OMNI www.omni.ac.uk
 Oncolink http://cancer.med.upenn.edu
 Altavista www.altavista.com
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28. Tracking the evidence
Formulate an
answerable
question
Track down the
best evidence
Critically appraise
the evidence
Integrate with
clinical expertise
and patient values
Medical news services
 Amadeus www.amedeo.com
 Intelihealth www.intelihealth.com
 Medscape www.medscape.com
 Reuters Health www.reutershealth.com
 Biomednet www.bmn.com
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29. Tracking the evidence
Formulate an
answerable
question
Track down the
best evidence
Critically appraise
the evidence
Integrate with
clinical expertise
and patient values
 d) Medical journals and textbooks
 Eg.
 Bandolier
 Clinical Evidence
 Cochrane Newsletters
 Most medical journals and quite a few
textbooks are now online
 By the time textbooks reach the book
stores, the information may get outdated
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30. Appraising Evidence
• Randomized Controlled Trials
• Case Control Studies
• Cohort Studies
• Case Reports
• Clinical Guidelines and Recommendations
• Systematic Reviews
• Meta-analysis
Formulate an
answerable
question
Track down the
best evidence
Critically appraise
the evidence
Integrate with
clinical expertise
and patient values
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31. Randomized Controlled Studies
 There are two groups, one treatment
group and one control group. The
treatment group receives the treatment
under investigation, and the control group
receives either no treatment or some
standard default treatment.
 Patients are randomly assigned to all
groups.
Standard method of answering questions about
the effectiveness of different therapies.
AppraisingEvidence
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32. The Double Blind Method
 A double blind study is one in which
neither the patient nor the physician
knows whether the patient is receiving
the treatment of interest or the control
treatment
• Reduces the risk of bias,
• It can eliminate the placebo effect
AppraisingEvidence
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33. The Double Blind Method
AppraisingEvidence
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34. Cohort Studies
 A Cohort Study is a study in which
patients who presently have a certain
condition and/or receive a particular
treatment are followed over time and
compared with another group who are
not affected by the condition under
investigation.
• Not as reliable as randomized controlled studies, since the two groups may
differ in ways other than in the variable under study
• They can end up taking a very long time
AppraisingEvidence
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35. Cohort Studies
AppraisingEvidence
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36. Case Control Studies
 Case control studies are studies in which
patients who already have a certain
condition are compared with people who
do not.
• Less reliable than either randomized controlled trials or cohort studies.
• They can be done quickly.
• Researchers don't need special methods, control groups, etc.
AppraisingEvidence
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37. Case Control Studies
AppraisingEvidence
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38. Case Series and
Case Reports
 Case series and case reports consist either of
collections of reports on the treatment of
individual patients, or of reports on a single
patient.
 A type of descriptive study
• A search for case series / case reports may reveal information
that will assist in a diagnosis.
• Have no statistical validity .
AppraisingEvidence
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39. Case Series and
Case Reports
AppraisingEvidence
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40. Descriptive Studies
 Examine differences in disease rates among populations in
relation to age, gender, race, and differences in temporal or
environmental conditions.
 Can only identify patterns or trends in disease occurrence
over time or in different geographical locations
 Cannot ascertain the causal agent or degree of exposure.
 Useful for generating hypotheses for further research
Eg.
• Case reports or case series,
• Surveillance systems,
• Correlational (ecologic studies),
• Cross-sectional studies
• Cluster investigations
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41. Systematic Reviews
 A systematic review is a comprehensive
survey of a topic in which all of the
primary studies of the highest level of
evidence have been systematically
identified, appraised and then
summarized according to an explicit and
reproducible methodology.
AppraisingEvidence
Gold standard in evidence based medicine
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42. Meta-Analyses
 A meta-analysis is a survey in which
the results of all of the included studies
are similar enough statistically that the
results are combined and analyzed as
if it was one study.
• Analysis of analyses
• Some kind of positive effect tend to be published more often than those
that do not. (Publication bias. )
AppraisingEvidence
Easy Option : To go for EBM Resources
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43. Meta-Analyses
AppraisingEvidence
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44. Evidence Pyramid
Evolution of the literature
AppraisingEvidence
As you move up the pyramid the amount of available literature decreases,
but increases in relevance to the clinical setting. (McKinnell and Elliott, 1997).
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45. An Example
 if you are interested in which interventions are most
effective for smoking cessation, search the Cochrane
Database of Systematic Reviews (CDSR) first.
 If there are no systematic reviews on your question, move
down to the next level of the pyramid (Randomized
Controlled Double Blind Studies).
 Look for reviews (DARE or ACP Journal Club) of single
well-designed randomized controlled trials.
 If appraised resources fail to provide evidence on your
question then you must search a large online medical
database like MEDLINE.
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46. Evidence (Study Design) Appropriate for Common
Question Types Matched to EBM Search Filters
Type of
Question
Study Design MEDLINE Search Filter
Terms
Therapy Systematic Reviews
and Meta-Analyses
Randomized
Controlled Studies
Double-blind Method
Meta-analysis
Random Allocation
Clinical Trial
Randomized Controlled Trial
Placebos
Multicenter Study
Random
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47. Levels of Evidence
Level Type of Evidence
I Evidence is obtained from meta-analysis of multiple,
well-designed, controlled studies. RCTs with low false-
positive and low false-negative errors (high power).
II Evidence is obtained from at least one well-designed
experimental study. Randomized trials with high false-
positive and/or negative errors (low power).
III Evidence is obtained from well-designed, quasi-
experimental studies such as non-randomized,
controlled single-group, pre-post, cohort, time, or
matched case-control series
IV Evidence is from well-designed, nonexperimental
studies such as comparative and correlational
descriptive and case studies
V Evidence from case reports and clinical examples
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48. Grading of Recommendation
Grade Grading of Recommendation
A There is evidence of type I or consistent
findings from multiple studies of types
II, III, or IV
B There is evidence of types II, III, or IV
and findings are generally consistent
C There is evidence of types II, III, or IV but
findings are inconsistent
D There is little or no systematic empirical
evidence
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49. Some examples of the way evidence ratings
will appear in the text of an article
• “To improve morbidity and mortality, most patients in CHF should be
treated with an angiotensin-converting enzyme inhibitor.
[Evidence level A, RCT]”
• “The USPSTF recommends that clinicians routinely screen
asymptomatic pregnant women 25 years and younger for chlamydial
infection.
[Evidence level B, nonrandomized clinical trial]”
• “The American Diabetes Association recommends screening for
diabetes every three years in all patients at high risk of the disease,
including all adults 45 years and older.
[Evidence level C, expert opinion]”
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50. Integrate with clinical
expertise and patient values
1. The patient's situation
2. The patient's desires and values
3. Your values
4. Your experience
5. Evidence from research
Formulate an
answerable
question
Track down the
best evidence
Critically appraise
the evidence
Integrate with
clinical expertise
and patient values
Elements That Help Form Your Clinical Decision
EBM helps supply you with 5 i.e. evidence from research.
It is up to you to judge how applicable that information is to your
patient and to decide on a course of action.
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51. What isWhat is notnot evidence-basedevidence-based
medicine?medicine?
Evidence-based medicine is not
"cook-book" medicine.
External clinical evidence can inform, but can never
replace, individual clinical expertise, and it is this
expertise that decides whether the external
evidence applies to the individual patient at all and,
if so, how it should be integrated into a clinical
decision.
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52. What isWhat is notnot evidence-basedevidence-based
medicine?medicine?
Evidence-based medicine is not
restricted to randomized trials and
meta-analyses.
It involves tracking down the best external
evidence with which to answer our clinical
questions.....
if no randomized trial has been carried out for our
patient’s predicament, we follow the trail to the
next best external evidence and work from there .
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53. EBM Resources
Cochrane Collaboration
PubMed Central
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54. - C.S.N.Vittal

55. 1. The question
 Does a normal ECG rule out a serious
elevation of potassium?
 Population – hyperkal*
 Indicator – ECG OR EKG
 Comparator -
 Outcome – hyperkal*
 Underline keywords; think of synonyms
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56. Diagnosis
button
* Means
any letters
“OR”
synonyms
PubMed
via Google
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57. Diagnosis
button
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58. Sensitivity of
62% or 55%
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59. Treating hyperkalemia
 She refused to go to hospital
 Resonium A, but it is around $100, which
she could not afford.
 My search had mentioned albuterol as a
treatment.
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61. Grade A recommendation (level 1A evidence)
•Treatment of acute infectious diarrhoea in children.
•Prevention of antibiotic associated diarrhoea.
•Prevention of nosocomial and community acquired diarrhoea in
children.
•Treatment of lactose malabsorption.
Grade A recommendation (level 1B evidence)
•Prevention of pouchitis and maintenance of remission.
•Prevention of postoperative infections.
•Prevention and management of paediatric atopic diseases.
Grade B recommendation (level 2 evidence)
•Prevention of travelers’ diarrhoea.
•Prevention of sepsis associated with severe acute pancreatitis.
•Maintenance of remission of ulcerative colitis.
•Lowering of blood cholesterol.
PROBIOTICS INPROBIOTICS IN
EVIDENCE BASED GASTROENTEROLOGYEVIDENCE BASED GASTROENTEROLOGY
Probiotics and human health: a clinical perspective
H S Gill and F Guarner Postgraduate Medical Journal 2004;80:516-526 © 2004
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62. Systematic review of bed rest
after medical procedures
Allen, Glasziou, Del Mar. Lancet, 1999
 10 trials of bed rest after spinal puncture
 no change in headache with bed rest
 Increase in back pain
 Protocols in UK neurology units - 80% still
recommend bed rest after LP
Serpell M, BMJ 1998;316:1709–10
 …evidence of harm available for 17 years
preceding...
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63. What is evidence-based medicine?What is evidence-based medicine?
It is the process of
 systematically finding,
 apprising and
 using contemporaneous research
findings
as the basis for clinical decisions.
Thus, EBM goes beyond reading an article and accepting the information as written.
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64. The Barriers to EBP
1. Attitude of question & inquiry
2. Know-how in finding, appraising,
and applying evidence
3. Information Resources on tap
4. Lack of Time
5. Cost Factor
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65. Conclusion
“Evidence can enhance clinical
judgment but can’t replace it.”
Evidence derived from critical
appraisal needs to be integrated with
clinical experience so that the patient
is benefited.
Such an approach can make clinical
decision-making easy and improve
the quality of care.
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66. "Kill as Few Patients as Possible"
- Oscar London
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