Evidence-Based Medicine 臨床應用

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

2. Medical Education in the New Century • Patient-centered care • Problem-based learning • Evidence-Based Medicine • Bioinformatics • 醫學人文教育

3. 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.

4. Moving From Opinion-based Medicine to Evidenced-based Medicine

6. Toss coins Guess “Do no harm.” Remember what you learned during your professional training Ask colleagues Text books Browse journals Searching bibliographic databases Decision Making in Health Care

8. History • Archie Cochrane : 1972 Effectiveness and Efficiency • Dave Sackett: 1980‘s at McMaster University: Canada • 1992:UK: Cochrane Collaboration by NHS(national health service) for review group. • 1997:USA:12 EBPC(evidence based practice center) by AHCPR.

9. Five Steps to Practice EBM • Step 1 - converting the need for information into an answerable question • Step 2 - searching the best evidence with which to answer that question • Step 3 – appraising the evidence for its validity, impact, and applicability • Step 4 –integratingthe evidence with our clinical expertise and patient • Step 5 –evaluating our effectiveness and efficiency

10. Asking Answerable Clinical Question

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

13. Benefits of Secondary Journal/database • Topic: clinical problem-based • Time: rapid and update • Form: brief summary • Application: ready to use

17. The Evidence Pyramid Randomized Controlled Double Blind Studies Meta - analysis Randomized Controlled Studies Cohort studies Case Control Studies Case Reports Ideas, Editorials, Opinions Animal research In vitro(Test tube) research

19. 數字會說話:以具體的數字呈現結果之可應用性數字會說話: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）

20. Diagnosis Sensitivity = a/a+c = 731/809 = 90% Specificity= d/ b+d = 1500/1770 = 85% LR+ = sens/(1- spec)= 90%/15% = 6 LR-=(1-sens)/spec= 0.12 Pre-test probability= a+c/a+b+c+d=32% Post-test probability= 73%

21. Calculation of OR/RR Odds ratio= (a/b)/(c/d)= 0.08 Relative risk=(a/a+b)/(c/c+d)= 0.11

22. Treatment Effects • Occurrence of diabetic retinopathy at 5 years among insulin-dependent diabetic in the DCCT trial • Usual insulin regimen(CER: control event rate): 38% • Intensive insulin regimen( EER: experimental event rate): 13%

23. Risk Reduction • Absolute risk reduction(ARR): 38%-13%=25% • Relative risk reduction(RRR): 25%/38%=66% • Number needed to treat(NNT)= 1/ARR =1/25%=4 patients • The number of patients that need to be treated to prevent one bad outcome

24. Harm • The 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%

25. Risk Increase • Absolute risk increase(ARI) =57-23%=34% • Relative risk increase(RRI) = 57-23/57= 60% • Number needed to harm(NNH)=1/ARI =1/34%= 3 patients • The number of patients that need to be treated to cause one bad outcome

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

29. Two Components of Guideline • The evidence component: international; Levels of evidence • The detailed instructional component: local; Grades of recommendation

30. 2001 Oct. Ministry of Health Singapore Clinical Practice Guidelines of glomerulonephritis • B - 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)

31. 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)

32. 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 outcome • Ann Intern Med 1996: Aspirin for secondary prevention of AMI in elderly

33. 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