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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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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