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ScienceCartoonsPlus.com. e vidence-based medicine (EBM)*: what it is & why its necessary. Rod Jackson 2013. * also called evidence-based practice (EBP). e vidence-based medicine (EBM)*: what it is?. - PowerPoint PPT PresentationTRANSCRIPT
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Rod Jackson 2013
evidence-based medicine (EBM)*: what it is & why its necessary
* also called evidence-based practice (EBP)
evidence-based medicine (EBM)*: what it is?
‘its about how to better inform your clinical decisions with the best up-to-
date epidemiological evidence’
core components of ‘traditional’ evidence based decision-making
system: policy / regulation /resources
patient’s clinical sta-tus*
patient’s values &
preferences
*relied on clinical knowledge or ‘mechanistic evidence’ mainly from:anatomy, physiology, pathology, biochemistry, psychology, etc.
‘modern’ EBM explicitly emphasises ‘current’ best clinical epidemiological evidence about
outcomes directly relevant to people
system issues
patient’sclinical status
mechanistic ev-idence
evidence from epidemiology
values/pref-erences
evidence from direct observation, what happens in practice
clinical epidemiological evidence*
• how accurate are diagnostic tests?
• how strong are prognostic markers?
• how effective are interventions?– therapy– Screening– prevention
* study of the probability of outcomes in groups of patients
Aristotle (384 – 322 BCE): the first evidence based practitioner?
None of the arts (i.e sciences) theorise about individual cases. Medicine, for instance, does not theorise about what will help to cure Socrates, but only about what will help to cure any or all of a given class of patients. This alone is our business. Individual cases are so infinitely various that no systematic knowledge of them is possible.
Aristotle. Rhetoric. book I, chapter 2: 1356b
(clinical epidemiology is the science of investigating the probability of outcomes in ‘groups ‘or classes’ of patients’)
evidence-based practice
‘informing decisions more explicitly with the best up-to-date evidence, particularly from
epidemiology’by using this evidence:
• more efficiently• more critically
• more systematically
EBP: informing decisions with the best up-to-date evidence
5,000?per day
2,000 per day
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ticle
s Per
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rwhy do we need to use evidence efficiently?
EBP: informing decisions with the best up-to-date evidence
Bastian, Glasziou, Chalmers PLoS 2010 Vol 7 | Issue 9 | e1000326more efficiently
clinical evidence increasing so rapidly we need better skills to keep up-to-date more efficiently than previous
generations of clinicians
validity: most articles should be ignored
EBM Journal Process
• 140+ journals scanned– 60,000 articles
• Is it valid? (<5%)– Intervention: RCT– Prognosis: inception cohort– Etc
• Is it relevant?– 6-12 GPs & specialists asked:
Relevant? Newsworthy?
• < 0.5% selected
Number Needed to Readto find 1 valid is 20+
Number Needed to Readto find 1 valid & relevant is 200+
using evidence more critically
more critically EBP: informing decisions with the best up-to-date evidence
but many clinicians cannot tell good from poor quality research
BMJ study of 607 reviewers– 14 deliberate errors inserted
Detection rates– On average <3 of 9 major errors detected– Poor Randomisation (by name or day) - 47%– Not intention-to-treat analysis - 22%– Poor response rate - 41%
Schroter S et al, accepted for Clinical Trials
more critically EBP: informing decisions with the best up-to-date evidence
Egger, M. et al. BMJ 1997;315:1533-1537
Total mortality from trials of β-blockers in 2° prevention after MI.
Black square & horizontal line correspond to odds ratio (OR) & 95% confidence interval (CI) for each trial. The size of the black square reflects the weight of each trial. The diamond represents the combined OR & 95 CI, showing a 22% reduction in odds of death
using evidence more systematically
Egger, M. et al. BMJ 1997;315:1371-1374
Cumulative meta-analysis of total
mortality results from trials of oral β-blockers
after MI.
Size of squares reflect amount of statistical
information available at a given point in time
using evidence more systematically
Gets worse with “duration in practice”
what skills will you need to keep up to date with the best
evidence?
• to find the evidence more efficiently• to appraise the quality of the evidence
more effectively• to use good quality evidence more
systematically
the steps of practicing EBM1. ask a focused question.2. access (systematically search for) epidemiological evidence to help answer question.3. appraise evidence found for its validity, effect size, precision (ideally all the relevant evidence)4. apply the evidence in practice:a. amalgamate the valid evidence with other relevant information (values & preferences, clinical/health issues, & system issues) and make an evidence-based decision; andb. act (implement) the decision in practice
explicitly improving practice with external evidence from literature
about 1/2 of ‘valid’ evidence today is out of
date in 5 years
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about 1/2 of valid evidence is not implemented
the 5th step of EBP = Quality Improvement
5. audit your practice:
compare your actual practice with best (evidence-based) practice
i.e. the gap between your evidence-based decisions and your actions
explicitly improving practice with internal evidence from your practice
GATE: Graphic Approach To Evidence Based Practice - a framework for learning the skills of EBP
1 picture, 2 formulas & 3 acronyms 20