實證醫學

徐圭璋2004.10.26

實証醫學

實者虛也，虛者實也﹖

EBM - Origins

• Paris School, mid 19th century -

Louis, Gavaret, Corvisart, Laennec, Bichat

• Archie Cochrane, Great Britain

• McMaster University, Canada

Sackett, Evidence Based Medicine 1997; Porter, The Greatest Benefit to Mankind, 1997; Cochrane, Effectiveness and Efficiency, 1989

“Leaks” between research & practice

Aware Accept Target Doable Recall Agree Done

ValidResearch

0.8 x 0.8 x 0.8 x 0.8 x 0.8 x 0.8 x 0.8 = 0.21

EBM - Response to Crisis

• Care that does not work

Walshe, Ham, Acting on the evidence, 1997

Is bed rest ever helpful?A systematic review of trials*

*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...

Bed Rest in Pregnancy• Pregnancy bed rest support

– www.pregnancybedrest.com/

• Cochrane Reviews– No benefit

EBM - Response to Crisis

• Care that does not work

• Clinicians overcome by information

Faber RG, Information Overload, BMJ, 1993; Sackett, EBM, 1997, 8-9

Rule 31 – Review the World Literature Fortnightly* *"Kill as Few Patients as Possible" - Oscar London

The research-to-awareness gap

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5,000?per day

1,260 per day55 per

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Managing InformationA comparison of sectors

• The Airline industry– Boeing 777 manuals

• 24 binders• 10 feet shelf space

– Conversion to CD• Reduced search by 60%

• The Health Industry– Memorize “the manuals”

– Exams, audits, etc to check

“Just in Time” learning:Intern’s information needs

• Setting: 64 residents at 2 New Haven hospitals• Method: Interviewed after 401 consultations• Questions

– Asked 280 questions (2 per 3 patients)– Pursued an answer for 80 questions (29%)– Not pursued because

• Lack of time• Forgot the question

• Sources of answers– Textbooks (31%), articles (21%), consultants (17%)

Green, Am J Med 2000

EBM - Response to Crisis

• Care that does not work

• Clinicians overcome by information

• Need for lifelong learning in health care

Davies et al, Evidence Based Practice, 1999, ch. 19; Shin JH,CMAJ, 1993; Bruner, The Process of Education, 1961; EBMWG, JAMA, 1992; Knowles, The Adult Learner, 1990; Vygotsky LS, Mind in Society, 1978

“Just in Time” learningThe EBM Approach to CME

• Shift focus to current patient problems(“just in time” education)– Relevant to YOUR practice

– Memorable – and behaviour changed!

– Up to date

• Skills and resources for best current answers

Dave Sackett

EBM - Response To Crisis

• Care that does not work

• Clinicians overcome by information

• Need for lifelong learning

• Need for critical consumption of information

Information “pull”Steps in EBM process

1. Formulate an answerable question

2. Track down the best evidence

3. Critically appraise the evidence

4. Integrate with clinical expertise and patient values

Identifying uncertainty

Ability to recognise uncertainty

+ degree of uncertainty

+ level of interest =

Level of success in presenting findings to colleagues

Finding relevant, high quality information

• Seeking multiple sources and resources

• Screening for relevance

• Assessing validity, methodological appropriateness

• Determining clarity and applicability

JAMA, Users Guides to the Medical Literature, 1993 onwards; Crombie IM, The Pocket Guide to Critical Appraisal, 1996; Pope & Mays, BMJ, 1995

The importance of analysing evidence in context

• Mark 1:• Mark 2:

• Mark 3:

• Find evidence and apply• Find evidence and apply critical

judgement and apply• Find evidence, apply critical

judgement, analyse whole stakeholder context, pursue decision analysis, and apply (or do not apply)

Greenhalgh T, Worrall JG, From EMB to CSM, J of Evaluation in Clinical Practice, 1997

Assessing barriers to considering evidence

• Personal barriers

• Organisational barriers• “Resistance to change is proportional to the

degree of discontinuity in the culture and/or power structure” (Ansoff, Corporate Strategy, 1987)

Schon, The Reflective Practitioner, 1983; Oxman et al, No Magic Bullets, CMAJ, 1995; Stocking B, Promoting Change in Clinical Care, Quality in Health Care, 1992

Using EBM to make decisions

• Complex decisions• Accountable decisions• Informed decisions• “An inherent part of the shift to EBM is the need

for professionals to demonstrate an awareness of the components of decision making” (CASP)

Mulrow et al, AIM, 1997; Wulff & Gotzsche, 2000; Sackett et al, BMJ, 1996, 312; (CASP), Evidence Based Health Care, Unit 1)

Evaluating the process• Did I identify an area of uncertainty that is a priority for

others?• Did I include all of the important sources of information? • Did I appraise all of the relevant articles?• Did I include others in the consideration of whether

evidence was transferable?• What was decided and why?• Was a change implemented and was it successful in

achieving the desired outcomes?

EBM

• Identify areas of clinical or managerial uncertainty

• Find and appraise research evidence• Analyse barriers to considering the applicability

of evidence• Develop a plan for introducing evidence or EB

skills• Make informed decisions about changing

practice, teaching and learning, or management• Evaluate the process