Evidence-Based Medicine

1. Evidence-Based Medicine

2. History • In the 1980s, in the northeastern United States studies showed that there were large variations in the amount of care delivered to similar populations. • The variation rate in the performance of cataract surgery was 2000%.

3. History • Physicians failed to recommend medications up to 10 years after they had been shown to be effective • Continue to recommend treatments up to 10 years after they have been shown to be useless

4. Definition • "Evidence-based medicine is the integration of best research evidence with clinical expertise and patient values." Sackett, D. L. (2000). Evidence-based medicine: How to practice and teach EBM(2nd ed.). Edinburgh; New York: Churchill Livingstone.

5. The four elements toevidence-based health care

6. Clinical expertise: the clinician’s cumulated experience, education, and clinical skills • Patient values: The patient brings to the encounter his or her own personal and unique concerns, expectiations, and values. • Best Research Evidence: usually found in clinically relevant research that has been conducted using sound methodology

7. Evidence-Based Medicine (EBM) • Evidence-Based Practice (EBP) • Evidence-Based Clinical Practice (EBCP) • Evidence-Based Health Care (EBHC) • Evidence-Based Nursing (EBN) Sackett’s definition refers to all of these; EBP and EBHC are more universally used.

8. Complex literature • A 2007 analysis of 1016 systematic reviews from all 50 Cochrane Collaboration Review Groups found that: • 44% of the reviews concluded that the intervention was "likely to be beneficial", 7% :"likely to be harmful", • 49% : "did not support either benefit or harm". • 96% recommended further research

9. what they would do if faced with a clinical problem? Seven alternatives to evidence based medicine

10. سرشناس و مشهور • Eminence based medicine—The more senior the colleague, the less importance he or she placed on the need for anything as mundane as evidence.

11. پر حرارت و جوش و خروش • Vehemence based medicine—The substitution of volume for evidence is an effective technique for brow beating your more timorous colleagues and for convincing relatives of your ability.

12. زبان آوری و آراستگی • Eloquence based medicine -- Sartorial elegance and verbal eloquence are powerful substitutes for evidence.-

13. مشیت الهی • Providence based medicine—If the caring practitioner has no idea of what to do next, the decision may be best left in the hands of the Almighty. Too many clinicians, unfortunately, are unable to resist giving God a hand with the decision making.

14. نداشتن اعتماد به نفس • Diffidence based medicine—Some doctors see a problem and look for an answer. Others merely see a problem. The diffident doctor may do nothing from a sense of despair. This, of course, may be better than doing something merely because it hurts the doctor's pride to do nothing.

15. نگرانی و ترس • Nervousness based medicine—Fear of litigation is a powerful stimulus to overinvestigation and overtreatment. In an atmosphere of litigation phobia, the only bad test is the test you didn't think of ordering.

16. اعتماد به نفس بالا • Confidence based medicine—This is restricted to surgeons

17. Six Steps in practicing EBM • Craft a clinical question • Search the medical literature • Find the study that is most able to answer this question • Perform a critical appraisal • Determine how the results will help you • Evaluate the results of applying the evidence

18. Steps in Practicing EBM • Convert the need for information into an answerable question. • Track down the best evidence with which to answer that question. • Critically appraise the evidence for its validity, impact, and applicability. • Integrate the evidence with our clinical expertise and our patient’s characteristics and values.

19. Good questions are the backbone of practicing EBM. It takes practice to ask the well-formulated question.

20. SPECIFIC KNOWLEDGE TYPE OF QUESTION GENERAL KNOWLEDGE CLINICAL EXPERIENCE The nature of the question asked is critically experience dependent.

22. Background questions: • are those which have been answered in the past and are now part of the “fiber of medicine.” • Answers to these questions are usually found in medical textbooks

23. Foreground questions are those usually found at the cutting edge of medicine. • They are questions about the most recent therapies, diagnostic tests, or current theories of illness causation. • These are the questions that are the heart of the practice of EBM.

24. PICO P= Patient or problem I = Intervention, prognostic factor, or exposure C=Comparison O=Outcomes (T)=Type of Study

25. Patient: Middle aged man with diabetes • Intervention: New drugs • Comparison: ARB (Losartan) • Outcome: adverse effects, BP control • Type: RCT, Metanalysis

26. Steps in Practicing EBM • Convert the need for information into an answerable question. • Track down the best evidence with which to answer that question. • Critically appraise the evidence for its validity, impact, and applicability. • Integrate the evidence with our clinical expertise and our patient’s characteristics and values.

27. The Evidence Pyramid Time Spent in Critical Appraisal Validity/Strength of Inference

29. This meta-analysis demonstrates that valsartan at doses of 160 and 320 mg is more effective in reducing BP than losartan at the 100 mg dose.

33. Steps in Practicing EBM • Convert the need for information into an answerable question. • Track down the best evidence with which to answer that question. • Critically appraise the evidence for its validity, impact, and applicability. • Integrate the evidence with our clinical expertise and our patient’s characteristics and values.

34. Types of Studies • Case series and Case Reports • Case control studies • Cohort studies • Randomized, controlled clinical trials • Systematic Reviews • Meta-analysis

35. Case series and Case reports • Collections of reports on the treatment of individual patients or a report on a single patient. • No control groups with which to compare outcomes, so limited statistical validity.

36. Case control studies • Patients who already have a specific condition are compared with people without the condition. Researcher looks back to identify factors or exposures possibly associated with the condition, often relying on medical records and patient recall. • Less reliable because showing a statistical relationship does not mean than one factor necessarily caused the other.  • Starts with patients who already have the outcome and looks backwards to possible exposures.

37. Cohort studies • Take a large population who are already taking a particular treatment or have an exposure, follow them forward over time, and then compare for outcomes with a similar group that has not been affected by the treatment or exposure. • Observational and not as reliable as randomized controlled studies, since the two groups may differ in ways other than in the variable under study.   • Starts with the exposure and follows patients forward to an outcome.

38. Randomized, controlled clinical trials • Carefully planned projects that introduce a treatment or exposure to study its effect on patients. • Include methodologies that reduce the potential for bias (randomization and blinding) and allow for comparison between intervention and control groups.  • Is an experiment and can provide sound evidence of cause and effect.   • Randomly assigns exposures and then follows patients forward to an outcome.

39. Systematic Reviews • Usually focus on a clinical topic and answer a specific question. An extensive literature search is conducted to identify studies with sound methodology. The studies are reviewed, assessed, and the results summarized according to the predetermined criteria of the review question. 

40. Meta-analysis • Thoroughly examines a number of valid studies on a topic and combines the results using accepted statistical methodology to report the results as if it were one large study.  • The Cochrane Collaboration has done a lot of work in the areas of systematic reviews and meta-analysis.