EBM

Medical Education in the New Century

Bioinformatics

Patient-centered care

Problem-based learning

Evidence-based medicine

(EBM, Evidence-based Medicine)

1972Archie Cochrane~ Randomized controlled trials

1992Archie Cochrane1993Cochrane Collaboration(Iain Chalmers, David Sackett)

Lancet Cochrane Collaboration

Dr. Sydney Burwell, Dean of Harvard Medical School

Half of what you are taught as medical students will in ten years have been shown to be wrong. And the trouble is, none of your teachers knows which half.

Use of current best evidence in making decisions about the care of individual patients

Not only a skill but also an attitude change

Conscientious, explicit, and judicious use of current best evidence in making decisions about individual patients. ~ Archie Cochrane 1972E B M

McMaster UniversityHIRUHealth Information Research UnitCochrane Collaboration http://hiru.mcmaster.ca/ Oxford University Centre for Evidence-Based Medicinehttp://cemb.jr2.ox.ac.uk American College of PhysicianACP ACP Journal Club Onlinehttp://www.acpjc.org

Step 1. Converting the need for information (about prevention, diagnosis, prognosis, therapy, causation, etc.) into an answerable question.

Step 2. Searching the best evidence with which to answer that question.

Step 3. Critically appraising the evidence for its validity (closeness to the truth), impact (size of the effect), and applicability (usefulness in our clinical practice).

Step 4. Integrating the evidence with our clinical expertise and patients unique biology, values and circumstances.

Step 5. Evaluating our effectiveness and efficiency in executing steps 1-4 and seeking ways to improve them both for next time.Five Steps to Practice EBM

The Evidence PyramidAnimal researchIn vitro (test tube) researchCase series/ReportsIdeas, Editorials, OpinionsCase Control StudiesCohort studiesRandomized Controlled StudiesRandomized Controlled Double Blind Studies Meta - analysis

asking an answerable question

searching the best evidence

critical appraisal the evidence

evaluation

Asking Answerable Clinical QuestionsWell-built clinical question

Background questionAsk general knowledge about a disorderHave two essential components:A question root (who, what, why, when) with a verbA disorder, or an aspect of a disorderForeground questionAsk for specific knowledge about managing patients with a disorderHave four (or three) essential components:1. Patient and/or problem2. Intervention (treatment)3. Comparison intervention4. Clinical outcomes

Patient ~ Who is the patient or what is the problem being addressed?

Intervention ~ What is the intervention?

Comparison ~ What are the alternatives?

Outcome ~ What are the outcomes?There are four elements of a well-formulated question

Searching The Best Evidence(primary journals or databases) ~ Medline, NEJM, Lancet

(secondary journals or databases) ~ ACP journal club, Cochrane.

(level of evidence)

update

ACP Journal Club: ACP Journal ClubAmerican College of Physicians Evidence-Based MedicineACP British Medical Journal Group50

DARE: Database of Abstracts of Reviews of Effectiveness National Health Services' Centre for Reviews and DisseminationNHS CRD DARE

CDSRCochrane Database of Systematic Reviews Cochrane Cochrane Collaboration

CCTRCochrane Central Register of Controlled Trials 300,000 RCTRandomized Controlled Trials CCT Clinical Controlled Trials Cochrane groups Medline EMBASE

EBM

CGMH PubMed: http://www.ncbi.nlm.nih.gov/PubMed/

1. ACP Journal Club: http://www.acpjc.org/ (1-4, 7)2. Cochrane ~ DARE (Database of Abstracts of Reviews of Effects)3.CDSR (Cochrane Database of Systematic Reviews) ~ Collaborative Review Groups http://www.cochrane.org/cochrane/revabstr/crgindex.htm 4.CCTR (Cochrane Central Register of Controlled Trials): 5.Cochrane collaberation 6.NGC (National Guideline Clearinghouse): http://guideline.org 7.Micromedex (CCIS) 8.Centre for Evidence-Based Medicine: http://www.cebm.net/ = http://cemb.jr2.ox.ac.uk 9.McMaster UniversityHIRUHealth Information Research UnitCochrane Collaboration: http://hiru.mcmaster.ca/10. American College of PhysicianACP: http://www.acponline.org 11.Bandolier: http://www.ebandolier.com = http://www.jr2.ox.ac.uk/bandolier/12.AHRQ website: http//www.ahrq.gov13.InfoPOEMs: http://www.infopoems.com 14.Other resources: http://www.google.com.tw/ www.yahoo.com/ http://www.mdconsult.com/15. 16.17. (HINT): http://www.hint.org.tw

The Evidence PyramidAnimal researchIn vitro (test tube) researchCase series/ReportsIdeas, Editorials, OpinionsCase Control StudiesCohort studiesRandomized Controlled StudiesRandomized Controlled Double Blind Studies Meta - analysis

Grade of RecommendationLevel of EvidenceTherapy[A]1aSystemic review of RCTs1bSingle RCT1cAll-or-none[B]2aSystemic review of cohort studies2bCohort study or poor RCT2cOutcomes research3aSystemic review of case-control studies3bCase-control study[C]4Case series[D]5Expert opinion, physiology, bench research

sensitivityspecificitylikelihood ratiopre-test probabilitypost-test probability

ARR (Absolute risk reduction) = EER (Experimental Event Rate) - CER (Control Event Rate) Number needed to treat, NNT=1/ARR relative risk reductionRRR

absolute risk increaseARI= EER (Experimental Event Rate) - CER (Control Event Rate) Number needed to harm, NNH=1/ARI

(Relative risk) (Odds) (Odds ratio) (confidence interval)

DiagnosisSensitivity = a/a+c = 731/809 = 90%Specificity= d/b+d = 1500/1770 = 85%Positive predictive value = a/a+b = 731/1001 = 73%Negative predictive value = d/c+d = 1500/1578 = 95%

LR+for a positive result = sens/(1- spec) = 90%/15% = 6LR- for a negative result = (1-sens)/spec = 10%/85% = 0.12Pre-test probability (prevalence)= a+c/a+b+c+d= 31%Pre-test odds = prevalence/(1-prevalence) = 31%/69% = 0.45Post-test odds = Pre-test odds Likelihood RatioPost-test probability= Post-test odds/(Post-test odds + 1)

Calculation of OR/RREER = a/a+b = 0.033CER = c/c+d = 0.30Relative risk= EER/CER = (a/a+b)/(c/c+d) = 0.11

Experimental event Odds = a/b = 0.034Control event Odds = c/d = 0.43Relative Odds = Odds ratio= (a/b)/(c/d) = ad/bc = 0.08Odd: a ratio of non-events to events

Asking Answerable Clinical Question

Patient/ProblemInsulin-dependent diabeticsInterventionIntensive insulin regimenComparisonRegular insulin regimenOutcomesRetinopathySymptomatic hypoglycemia

Treatment EffectsOccurrence of diabetic retinopathy at 5 years among insulin-dependent diabetic in the DCCT trialUsual insulin regimen (CER: control event rate): 38%Intensive insulin regimen (EER: experimental event rate): 13%

Risk Reduction (calculation)Absolute risk reduction (ARR) = CER-EER = 38%-13% = 25%Relative risk reduction (RRR) = CER-EER/CER = 25%/38% =66%Number needed to treat (NNT) = 1/ARR = 1/25% = 4 patientsThe number of patients that need to be treated to prevent one bad outcome or get one good outcome.

HarmThe proportion of patients with at least one episode of symptomatic hypoglycemia Usual insulin regimen (CER: control event rate): 23%Intensive insulin regimen (EER: experimental event rate): 57%

Risk Increase (calculation)Absolute risk increase (ARI) = EER - CER = 57% - 23% = 34% Relative risk increase (RRI) = EERCER/CER = 57% - 23%/23% = 148%Number needed to harm (NNH)=1/ARI = 1/0.34= 3 patients ()The number of patients that need to be treated to cause one bad outcome (being harmed)

Treatment of Class III-IV Lupus Nephritis

Meta-Analysis

Treatment of diffuse proliferative lupus nephritis: A meta-analysis of randomized controlled trialsAm J Kidney Dis. 2004 Feb;43(2):197-208. Cochrane Renal Group Cochrane Database of Systematic Reviews. 1, 2004.

Values of RR less than 1 indicate a reduction in risk for the outcome with the experimental treatment. Conversely, values of RR more than 1 indicate an increase in risk. The 95% CIs are a measure of variability in the precision of the RR estimate and its statistical significance. Heterogeneity of treatment effects between studies was investigated by visual examination of graphic meta-analysis plots and from the Cochran Q (heterogeneity chi-square) and I2 statistic.This is a forest plot, with a vertical line at 1.0 representing equivalence in risk for an outcome with experimental and control treatment (null hypothesis). The RR for each outcome and its 95% CI are indicated by a solid square and a line. The size of the solid square represents the contribution (weight) of the trial to the analysis. Diamond-shaped symbols represent the summary estimator of overall effect pooling the weighted effect of individual RCTs.

medical decision making technique accessing medical information assessing the validity of medical information (RCT randomized controlled trials) guidelineclinical pathway

(health care-provider)

(clinical practice guideline) Clinical Practice Guidelines

Resource Centers for GuidelinesNGC - National Guideline Clearinghouse http://www.guideline.govAGREE - appraisal of guideline research & evaluation http://www.agreecollaboration.org/Guidelines International Network http://www.g-I-n.net/SIGN - Scottish Intercollegiate Guidelines Network http://www.sign.ac.uk/

Decision tree analysis

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EBMEBM introduction94.03 EBM workshop

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929PGY186-10PGY112:00~13:008A-8BEBMPGY1

Interpretation of evidence is subjective: it dependents on how you view it.

Clinical Practice GuidelinesSystemically developed statements to assist practitioner and patient decisions about appropriate health care for specific clinical circumstances.

Purpose ~ to make explicit recommendations with a definite intent to influence what clinicians do.