Evidence-Based Medicine臨床應用張明揚醫師 長庚醫院內科部2002-7-2

Medical Education in the New Century

Patient-centered careProblem-based learningEvidence-Based MedicineBioinformatics醫學人文教育

Evidence-based Medicine

Use of current best evidence in making decisions about the care of individual patients.Not only a skill but also an attitude change.

Moving From Opinion-based Medicine to

Evidenced-based Medicine

http://www.latinworld.com/magazine/images/ni-art-sm.jpg

Decision Making in Health Care

Toss coinsGuess“Do no harm.”Remember what you learned during your professional training

Ask colleaguesText booksBrowse journalsSearching bibliographic databases

HistoryArchie Cochrane : 1972 Effectiveness and EfficiencyDave Sackett: 1980‘s at McMaster University: Canada1992:UK: Cochrane Collaboration by NHS(national health service) for review group. 1997:USA:12 EBPC(evidence based practice center) by AHCPR.

Five Steps to Practice EBMStep 1 - converting the need for information into an answerable questionStep 2 - searching the best evidence with which to answer that questionStep 3 – appraising the evidence for its validity, impact, and applicabilityStep 4 – integrating the evidence with our clinical expertise and patientStep 5 – evaluating our effectiveness and efficiency

Asking Answerable Clinical Question

Patient/Problem Insulin-dependent diabetics

Intervention Intensive insulin regimen

Comparison Regular insulin regimen

Outcomes RetinopathySymptomatic hypoglycemia

A 55 y/o man, Mr. Ronado, came with severe CHF, does spironolactone combined with usual care(ACEI + beta blocker) reduce the mortality?

Benefits of Secondary Journal/database

Topic: clinical problem-basedTime: rapid and updateForm: brief summaryApplication: ready to use

The Evidence Pyramid

Animal researchIn vitro(Test tube) research

Case Reports

Ideas, Editorials, Opinions

Case Control Studies

Cohort studies

Randomized Controlled Studies

Randomized Controlled Double Blind Studies

Meta - analysis

Grade of Recommendation

Level of Evidence

Therapy

[A] 1a Systemic review of RCTs

1b Single RCT

1c ‘All-or-none’

[B] 2a Systemic review of cohort studies

2b Cohort study or poor RCT

2c ‘Outcomes’ research

3a Systemic review of case-control studies

3b Case-control study

[C] 4 Case series

[D] 5 Expert opinion, physiology, bench research

數字會說話 :以具體的數字呈現結果之可應用性敏感度（ sensitivity）、特異度（ specificity）、概數比率（ likelihood ratio）、檢測前機率（ pre-test probability）、檢測後機率（ post-test probability）、信賴區間 (confidence interval)相對危險度減少百分比（ relative risk reduction， RRR）、絕對危險度減少百分比（ absolute risk reduction， ARR）、避免一位病患罹患某種疾病所需治療人數（ number needed to treat， NNT）、避免一位病患罹患某種疾病造成的醫源性傷害人數（ number needed to harm， NNH）

DiagnosisDiagnostic test(serum ferritin)

IDAPresent absent

Positive( < 65) (731) a (270) bNegative( >65) (78) c (1500) dSensitivity = a/a+c = 731/809 = 90%

Specificity= d/ b+d = 1500/1770 = 85%LR+ = sens/(1- spec)= 90%/15% = 6LR-=(1-sens)/spec= 0.12Pre-test probability= a+c/a+b+c+d=32%Post-test probability= 73%

Calculation of OR/RRTreatment (Baktar for cirrhosis)

Adverse Outcome(Infection)

Positive Negative

Positive A=1 B=29Negative C=9 D=21Odds ratio= (a/b)/(c/d)= 0.08

Relative risk=(a/a+b)/(c/c+d)= 0.11

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 ReductionAbsolute risk reduction(ARR): 38%-13%=25%Relative risk reduction(RRR): 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

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): 47%

Risk IncreaseAbsolute risk increase(ARI) =57-23%=34% Relative risk increase(RRI) = 57-23/57= 60%Number needed to harm(NNH)=1/ARI =1/34%= 3 patientsThe number of patients that need to be

treated to cause one bad outcome

Now apply the evidence to your patient. Discuss with Mr. Ronado and add aldactone.

Two Components of Guideline

The evidence component: international; Levels of evidenceThe detailed instructional component: local; Grades of recommendation

2001 Oct. Ministry of Health Singapore Clinical Practice

Guidelines of glomerulonephritisB - A target blood pressure <125/75 mmHg (mean arterial pressure <92 mmHg) is recommended for patients with serum creatinine <600 micromol/l and total urinary protein excretion >1 g/day. (Grade B, level III)C - A target blood pressure <130/ 80 mmHg (mean arterial pressure <98 mmHg) is recommended for patients with serum creatinine <600 micromol/l and total urinary protein excretion <1 g/day. (Grade C, level IV)

2001 Oct. Ministry of Health Singapore Clinical Practice

Guidelines of glomerulonephritis

A - Angiotensin converting enzyme inhibitor therapy is preferable to conventional therapy for treatment of hypertension in patients with glomerulonephritis as it confers greater renoprotection. (Grade A, level Ib)B - Angiotensin converting enzyme inhibitor therapy is preferable to calcium channel blockers for treatment of hypertension in patients with glomerulonephritis as it confers greater renoprotection. (Grade B, level III)

Evidence of EBM???Does providing evidence-based care improve outcomes for patients?Difficult to overcome the problem of ethical concerns and study design.Population-based outcomes research: evidence-based therapies have better outcomeAnn Intern Med 1996: Aspirin for

secondary prevention of AMI in elderly

結論與展望始於病人而用於病人發現臨床問題帶動研究風氣臨床指引 ( 學會 , 健保局及醫院 )醫學教育增加實證醫學訓練終身學習的工具將有限的資源運用於具實證的醫療