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EVIDENCE-BASED MEDICINE

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  1. EVIDENCE-BASED MEDICINE

  2. Half of what we learn in medical school is wrong…. We just don’t know which half.

  3. OUTLINE 1. What is EBM? 2. The EBM Cycle 3. Misconceptions about EBM 4. Prerequisites for the practice of EBM

  4. WHAT IS EBM?

  5. EVIDENCE-BASED MEDICINE “A PARADIGM SHIFT IN MEDICAL PRACTICE …” Guyatt GH. Ann Intern Med, 114(52): A16, 1991.

  6. During Postrevolutionary Paris, clinician Pierre Louis : rejected authorities’ pronouncements, demanded systematic observations of patients (eg venosection for cholera) Reign of Emperor Qianlong: “kaozheng” - practicing evidential research to interpret Confucian texts

  7. EVIDENCE PREFERENCES EXPERTISE Anecdotes Gestalt 6th Sense Rules of Thumb Tacit Knowledge CLINICAL DECISION-MAKING EVIDENCE EXPERTISE EMOTION-BASED MEDICINE

  8. EVIDENCE -BASED MEDICINE (DEFINITION) INTEGRATION OF 1. Best research evidence 2. Clinical expertise 3. Patient values IN CLINICAL DECISIONS

  9. THE EBM CYCLE

  10. THE EBM CYCLE CLINICAL QUESTION SYSTEMATIC SEARCH FOR “BEST EVIDENCE” MEDICAL HEURISTICS DATA INTEGRATION CRITICAL APPRAISAL

  11. A. ASKING A CLINICAL QUESTION YOU CAN ANSWER THE EBM CYCLE

  12. EXAMPLE ELEMENTS OF A WELL-BUILT CLINICAL QUESTION 1. Patient or problem Among low-birth weight neonates... 2. Intervention Would adding corn oil to their milk formula… 3. Comparison intervention Compared to placebo... 4. Outcome Lead to faster weight gain?

  13. THE EBM CYCLE B. SEARCHING THE LITERATURE

  14. MILLIONS OF ARTICLES 12 10 8 6 4 2 0 66 69 72 75 78 81 84 87 90 93 96 99 02 INDEX MEDICUS CITATIONS

  15. 1. COMPUTERIZED SEARCHES 2. MANUAL SEARCHES 3. MAJOR TEXTBOOKS 4. ANCESTRY METHOD 5. ASKING EXPERTS INFORMATICS TOOLS

  16. THE EBM CYCLE C. APPRAISING THE EVIDENCE

  17. CLAIMS OF EFFECTIVENESS CLAIMS OF ACCURACY CLAIMS ON CAUSATION CLAIMS ON PROGNOSIS RULES OF EVIDENCE

  18. 1. INSIST ON RANDOMIZED CONTROLLED TRIALS (WHEN FEASIBLE) 2. INSIST ON CLINICALLY RELEVANT OUTCOMES 3. APPRAISE THE MAGNITUDE OF CLINICAL BENEFIT RULES OF EVIDENCE FOR CLAIMS OF EFFECTIVENESS

  19. WHY INSIST ON RANDOMIZED CONTROLLED TRIALS ?

  20. GHIDINI et al, 1988 L-CARN (21) FINDING PRE POST 20 2 DYSPNEA 21 NVE 0 EDEMA 21 1 15 CHF CL. 4 1

  21. 17 1 17 2 3 17 12 5 GHIDINI et al, 1988 L-CARN (21) PLCBO (17) FINDING PRE POST PRE POST 20 2 DYSPNEA 21 NVE 0 EDEMA 21 1 15 CHF CL. 4 1

  22. CORONARY DRUG PROJECT (ACUTE MI); NEJM 1980 N MR % GROUP 1813 16 % TOOK DRUG A DID NOT 882 26 % p=0.0000000073 (40 RFs ADJUSTED)

  23. WHY INSIST ON CLINICALLY RELEVANT ENDPOINTS?

  24. PLA DRUG X SERUM CHOL +1.00% -9.00% NONFATAL MI 0.72% 0.58% 0.74% TOTAL MI 0.89% 0.62% DEATHS 0.52% EFFECT OF DRUG X ON ASYMPTOMATIC PATIENTS W/ HYPERCHOLESTEROLEMIA

  25. CLINICAL ENDPOINT MECHANISTIC ENDPOINT TREATMENT ENCAINIDE & FLECAINIDE FOR ACUTE MI DECREASED PVCs INCREASED MORTALITY DIPYRIDAMOLE FOR ANGINA CORONARY VASODILATOR CAN PROVOKE ANGINA

  26. O2 in premature Babies Vit E to prevent CAD Chloramphenicol in Neonates Vit A in cancer prevention SOME WIDELY USED TREATMENTS THAT WERE PROVEN TO BE USELESS OR HARMFUL BY RCT

  27. WHY APPRAISE THE MAGNITUDE OF CLINICAL BENEFIT?

  28. VACCINE N POLIO SALK 200,745 SALINE 200,229 RELATIVE RISK REDUCTION .071% - .028% .071% = = 61% ABSOLUTE RISK REDUCTION = .O71% - .028% = .043% SUMMARY OF EVIDENCE POLIO VACCINE TRIAL 1954 .028% .071%

  29. ABSOLUTE RISK REDUCTION = .071% - .028% = .043% SUMMARY OF EVIDENCE POLIO VACCINE TRIAL 1954 NNT = 2325 PATIENTS COST PER POLIO PREVENTED? = 2325 PTS. X P150 = P350T TO PREVENT 1 polio case

  30. cost 27M 730T 350T INTERVENTION OUTCOME TX C NNT DEATH FROM CAD STATIN FOR HYPERCHOL. 3.2 4.1 111 INH FOR INACTIVE TB ACTIVA-TION OF TB .25 1.0 133 CLINICAL POLIO POLIO VACCINE FOR HEALTHY CHILD .028 .071 2325

  31. THE EBM CYCLE D. INTEGRATING THE DATA

  32. TYPES OF INTEGRATIVE STUDIES REVIEW = any 2 articles (or more) OVERVIEW = comprehensive, systematic and objective search META-ANALYSIS = results of trials are combined statistically GUIDELINES = actual recommendations on management are made

  33. RISKt RISKc RELATIVE RISK = ------> BENEFICIAL RR < 1 ------> USELESS RR = 1 ------> HARMFUL RR > 1 POINT ESTIMATE INTERVAL ESTIMATE RR = 0.65 [95% CI: 0.60, 0.70]

  34. RR for ADVERSE EVENT [0.42, 0.88] 0.61 STUDY 1 STUDY 2 3.12 [1.57, 4.38] STUDY 3 0.52 [0.21, 1.27] STUDY 4 2.40 [1.00, 5.20] STUDY 5 0.48 [0.18, 1.00] 0.57 [0.58, 0.86] TOTAL 0.10 1.0 10.0

  35. 0.61 (0.41, 0.90) 0.18 (0.02, 1.47) 0.55 (0.23, 1.34) 0.23 (0.07, 0.76) 0.38 (0.10, 1.39) 0.23 (0.07, 0.76) 0.94 (0.60, 1.50) 0.65 (0.50, 0.83) STEROIDS IN PRE-TERM LABOR - EFFECT ON NEONATAL MORTALITY Auckland Block Morales Tauesch Morrison Amsterdam US Steroid Trial TOTAL 0.1 1.0 10.0

  36. INTERNATIONAL COCHRANE COLLABORATION

  37. JOURNALS & CONFERENCES GUIDELINE DEVELOPMENT BASIC CLINICAL RESEARCH PRACTITIONER DISSEMINATION PATIENT GUIDELINE DEVELOPMENT MODEL

  38. THE EBM CYCLE E. MAKING A DECISION

  39. “Primum Non Nocere.” “Alpha error is graver than beta error.”

  40. “A drug should not be given because it ought to work but because it does...” Opie L, 1991

  41. THE EBM CYCLE CLINICAL QUESTION SYSTEMATIC SEARCH FOR “BEST EVIDENCE” MEDICAL HEURISTICS DATA INTEGRATION CRITICAL APPRAISAL

  42. EBM AS A LEARNING TOOL PASSIVE SEARCHES (TRAD’L) ACTIVE SEARCHES (EBM) ANNUAL CONVENTIONS DAILY PROBLEMS SELF-DIRECTED LEARNING OCC. JOURNAL BROWSING “JUST IN CASE” METHOD “JUST IN TIME” METHOD

  43. MISCONCEPTIONS ABOUT EBM: What EBM is not 1. Not old-hat 2. Not impossible to practice 3. Not ‘cook-book’ medicine 4. Not alwayscost minimizing 5. Not RCT / meta-analysis only

  44. EBM is NOT a religion!

  45. EBM Figure 1. The Cochrane symbol, seen here in plans for the facade of the Cochranite Vatican that is to be built in Summertown

  46. 1. Mastery of clinical skills: patient-interviewing and PE 2. Practice of continuous life-long self-directed learning 3. Humility 4. Enthusiasm and irreverence PREREQUISITES FOR THE PRACTICE OF EBM

  47. IMPACT OF EBM • SHORT TERM: • BETTER MDs • MEDIUM TERM: • POTENTIAL RESEARCHERS • LONG TERM: • POTENTIAL POLICY MAKERS • AND OPINION LEADERS

  48. SUMMARY 1. What is EBM? 2. The EBM Cycle 3. Misconceptions about EBM 4. Prerequisites for the practice of EBM