2. EVIDENCE BASED MEDICINE
Dr. Yasser Ahmed Abdelrahman
Lecturer of anesthesia and intensive care
Ain shams university, Faculty of Medicine June, 2012

3. Hypo-ti-thenai To put under or Suppose
HYPETHESIS
Hypo-ti-thenai To put under or Suppose

4. HYPETHESIS
observation
understanding
intuition

6. HYPOTHESIS TESTING
observation
understanding
intuition

7. CLINICAL DECISION

9. Evidence-based medicine is the integration of the best available research evidence with clinical expertise and patient values.

10. EBM is the process of systematically reviewing, appraising and using clinical research findings to aid the delivery of optimum clinical care to patients

11. Steps to deliver optimal clinical care
Production of evidence.
Production of guidelines.
Implementation of guidelines.
Evaluation of compliance.

13. 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.

14. Developing clinical questions
“To get the right answer,
you must first ask the right question.”

15. Developing the clinical question
Step 1: Formulate the clinical issue into a searchable, answerable question.
Step 2: Distinguish what type of question you may have.
Background
Foreground
Experience with Condition

16. Background questions are typically answered by textbooks.
Background questions ask for general information about a condition or thing.
A question root (who, what, when, etc) combined with a verb.
What modes of ventilation can cause barotrauma?
Background questions are typically answered by textbooks.

17. Foreground questions
Foreground questions ask for specific knowledge about a specific patient with a specific condition.
Is APRV protective against barotrauma in patients with ARDS?
Foreground questions are typically answered by databases that access the research literature

18. Differences in Type of ?’s
General
Specific
“Background” question composed of question modifier and condition.
Cover the full range of biologic, psychologic, or sociologic aspect of human illness
Can be answered by reference works.*
Can be used as a trampoline for generating specific questions to be answered by EBM.
“Foreground” question composed of patient and/or problem, intervention (therapy, diagnostic test, etc.), comparison and outcome.
Often requires more comprehensive and intensive search strategies (not necessarily more time consuming).
Suitable to answering using the techniques of EBM.

19. Formulate A Foreground Clinical Question
Formulate three part question
(P) The patient population or the problem the patient is suffering from
(I) The intervention and/or (C) comparison
(O) The outcome
(PICO)

20. Types of Questions
Diagnosis: How to select a diagnostic test or how to interpret the results of a particular test.
Prognosis: What is the patient's likely course of disease, or how to screen for or reduce risk.
Therapy: Which treatment is the most effective, or what is an effective treatment for a particular condition.
Harm or Etiology: Are there harmful effects of a particular treatment, or how these harmful effects can be avoided.
Prevention: How can the patient's risk factors be adjusted to help reduce the risk of disease?
Cost: Looks at cost effectiveness, cost/benefit analysis.

21. Question Templates for Asking PICO Questions Therapy In __________________, what is the effect of ____________________ on ______________________ compared with __________________? Etiology Are ______________ who have _________________ at ________________ risk for/of ____________________ compared with _____________________ with/without ______________________? Diagnosis or Diagnostic Test Are (Is) _________________________ more accurate in diagnosing ________________ compared with ________________? Prevention For _________________ does the use of _______________ reduce the future risk of ________________ compared with _________________? Prognosis Does _______________ influence _________________ in patients who have __________________?
Melnyk, B. M., & Fineout-Overholt, E. (2005). Evidence-based practice in nursing & healthcare : A guide to best practice. Philadelphia, PA: Lippincott Williams & Wilkins.

22. Well Formulated ?’s
Focus scarce learning time on evidence directly relevant to patient’s needs and our particular knowledge needs.
Suggest high-yield search strategies.
Help us to model life-long learning techniques for our colleagues and students.
Are answerable and, thus, reinforce the satisfaction of finding evidence that makes us better, faster clinicians.

23. 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.

24. Track down the best evidence
Ask your librarian
Use search engine

25. Medical literature Primary – original research
Experimental (an intervention is made or variables are manipulated)
Randomized Control Trials
Controlled trials
Observational (no intervention or variables are manipulated)
Cohort studies
Case-control studies
Case reports
Secondary – reviews of original research
Meta-analysis
Systematic reviews
Practice guidelines
Reviews
Decision analysis
Consensus reports
Editorial, commentary

26. Evidence Pyramid Meta-analysis Systematic Review
Randomized Controlled Trial
Cohort Studies
Case Control Studies
Case Series/Case Reports
Animal Research

27. STUDY DESIGN APPROPRIATE TO OBJECTIVES
Prevalence
Cause
Therapy
Prognosis

28. Type of Question
Suggested Best Type of Study
Therapy
RCT > cohort > case control > case series
Diagnosis
Prospective, blind comparison to gold standard
Etiology / Harm
Prognosis
Cohort study > case control > case series
Prevention
RCT > cohort study > case control > case series
Clinical Exam
Cost
Economic analysis
Questions of therapy, etiology and prevention which can best be answered by RCT can also be answered by a meta-analysis or systematic review.

29. Levels of evidence Level I: Level II-1: Level II-2: Level II-3:
obtained from at least one properly controlled randomized trial, considered the gold standard of evidence.
Level II-1:
derived from controlled trials without randomization.
Level II-2:
well-designed cohort or case-control studies.
Level II-3:
includes studies with external control groups or ecological studies.
Level III
evidence is derived from reports of expert committees, not because it is weaker than levels I or II, but because it is often difficult to ascertain the scientific origin of the committee opinion.

30. Levels of Evidences
(I-1) a well done systematic review of 2 or more RCTs
(I-2) a RCT
(II-1) a cohort study
(II-2) a case-control study
(II-3) a dramatic uncontrolled experiment
(III) respected authorities, expert committees, etc..
(IV) ...someone once told me....
See also AAFP

31. IMRAD format
Introduction: why the authors decided to conduct the research.
Methods: how they conducted the research and analyzed their results.
Results: what was found. And
Discussion: what the authors think the results mean.

32. PP-ICONS Problem Patient or population Intervention Comparison Outcome
Number of subjects
Statistics
Flaherty, Robert J. A simple method for evaluating the clinical literature. Fam Prac Mgt, May 2004; Available online at

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. Critical Appraisal STUDY DESIGN APPROPRIATE TO OBJECTIVES
STUDY SAMPLE REPRESENTATIVE
CONTROL GROUP ACCEPTABLE
QUALITY OF MEASUREMENTS AND OUTCOMES
COMPLETENESS
DISTORTING INFLUENCES

35. Critical Appraisal STUDY SAMPLE REPRESENTATIVE Source of sample
Sampling method
Sample size
Entry criteria and exclusion
Non-respondents

36. Critical Appraisal STUDY DESIGN APPROPRIATE TO OBJECTIVES
STUDY SAMPLE REPRESENTATIVE
CONTROL GROUP ACCEPTABLE
QUALITY OF MEASUREMENTS AND OUTCOMES
COMPLETENESS
DISTORTING INFLUENCES

37. Critical Appraisal CONTROL GROUP ACCEPTABLE Definition of controls
Source of controls
Matching and randomization
Comparable characteristics

38. Critical Appraisal STUDY DESIGN APPROPRIATE TO OBJECTIVES
STUDY SAMPLE REPRESENTATIVE
CONTROL GROUP ACCEPTABLE
QUALITY OF MEASUREMENTS AND OUTCOMES
COMPLETENESS
DISTORTING INFLUENCES

39. Critical Appraisal QUALITY OF MEASUREMENTS AND OUTCOMES Validity
Reproducibility
Blindness
Quality control

40. Critical Appraisal STUDY DESIGN APPROPRIATE TO OBJECTIVES
STUDY SAMPLE REPRESENTATIVE
CONTROL GROUP ACCEPTABLE
QUALITY OF MEASUREMENTS AND OUTCOMES
COMPLETENESS
DISTORTING INFLUENCES

41. Critical Appraisal COMPLETENESS Compliance Drop outs and deaths
Missing data

42. Critical Appraisal STUDY DESIGN APPROPRIATE TO OBJECTIVES
STUDY SAMPLE REPRESENTATIVE
CONTROL GROUP ACCEPTABLE
QUALITY OF MEASUREMENTS AND OUTCOMES
COMPLETENESS
DISTORTING INFLUENCES

43. Critical Appraisal DISTORTING INFLUENCES Extraneous treatments
Contamination
Changes over time
Confounding factors
Distortion reduced by analysis

44. Critical Appraisal STUDY DESIGN APPROPRIATE TO OBJECTIVES
STUDY SAMPLE REPRESENTATIVE
Source of sample
Sampling method
Sample size
Entry criteria and exclusion
Non-respondents
CONTROL GROUP ACCEPTABLE
Definition of controls
Source of controls
Matching and randomization
Comparable characteristics
QUALITY OF MEASUREMENTS AND OUTCOMES
Validity
Reproducibility
Blindness
Quality control
COMPLETENESS
Compliance
Drop outs and deaths
Missing data
DISTORTING INFLUENCES
Extraneous treatments
Contamination
Changes over time
Confounding factors
Distortion reduced by analysis

45. Limitations*
Time.
Shortage of coherent and consistent scientific evidence (therapeutic nihilism).
Challenges of applying evidence to care of individual patients.
General barriers to the practice of quality medicine (e.g. costs, patient expectations, etc.).

46. IS EVIDENCE BASED MEDICINE DEAD
IS EVIDENCE BASED MEDICINE DEAD? Trisha Greenhalgh Professor of Primary Care University College London

47. Who ask the question
Who set the research agenda
Who say RCTs are objective
Who say RCTs are generalizable
What about clinical freedom
What about the patient perspective
What about the doctor’s hunch
What about the service reality
What about the political priority