Dr yasser ahmed abdelrahman lecturer of anesthesia and intensive care
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Dr. Yasser Ahmed Abdelrahman Lecturer of anesthesia and intensive care Ain shams university, Faculty of Medicine June, 2012. EVIDENCE BASED MEDICINE. HYPETHESIS. Hypo-ti-thenai To put under or Suppose. HYPETHESIS. observation. understanding. intuition. HYPOTHESIS TESTING.

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Dr. Yasser Ahmed Abdelrahman Lecturer of anesthesia and intensive care

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Dr. Yasser Ahmed Abdelrahman

Lecturer of anesthesia and intensive care

Ain shams university, Faculty of MedicineJune, 2012

EVIDENCE

BASED

MEDICINE


HYPETHESIS

Hypo-ti-thenaiTo put under or Suppose


HYPETHESIS

observation

understanding

intuition


HYPOTHESIS TESTING

observation

understanding

intuition


CLINICAL DECISION


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


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


Steps to deliver optimal clinical care

  • Production of evidence.

  • Production of guidelines.

  • Implementation of guidelines.

  • Evaluation of compliance.


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.


Developing clinical questions

“To get the right answer,

you must first ask the right question.”


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


Background questions

  • 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.


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


“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.

Differences in Type of ?’s

General

Specific


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)


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.


Question Templates for Asking PICO QuestionsTherapyIn __________________, what is the effect of ____________________ on ______________________ compared with __________________?EtiologyAre ______________ who have _________________ at ________________ risk for/of ____________________ compared with _____________________ with/without ______________________?Diagnosis or Diagnostic TestAre (Is) _________________________ more accurate in diagnosing ________________ compared with ________________?PreventionFor _________________ does the use of _______________ reduce the future risk of ________________ compared with _________________?PrognosisDoes _______________ 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.


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.


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.


Track down the best evidence

  • Ask your librarian

  • Use search engine


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


Evidence Pyramid

Meta-analysis

Systematic Review

Randomized Controlled Trial

Cohort Studies

Case Control Studies

Case Series/Case Reports

Animal Research


  • STUDY DESIGN APPROPRIATE TO OBJECTIVES

Prevalence

Cause

Therapy

Prognosis


Levels of evidence

  • Level I:

    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.


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....

    • http://www.phru.org/casp/

    • See also AAFP


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.


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;47-52. Available online at http://www.aafp.org/fpm/20040500/47asim.html.


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.


STUDY DESIGN APPROPRIATE TO OBJECTIVES

STUDY SAMPLE REPRESENTATIVE

CONTROL GROUP ACCEPTABLE

QUALITY OF MEASUREMENTS AND OUTCOMES

COMPLETENESS

DISTORTING INFLUENCES

Critical Appraisal


Critical Appraisal

  • STUDY SAMPLE REPRESENTATIVE

    • Source of sample

    • Sampling method

    • Sample size

    • Entry criteria and exclusion

    • Non-respondents


Critical Appraisal

  • STUDY DESIGN APPROPRIATE TO OBJECTIVES

  • STUDY SAMPLE REPRESENTATIVE

  • CONTROL GROUP ACCEPTABLE

  • QUALITY OF MEASUREMENTS AND OUTCOMES

  • COMPLETENESS

  • DISTORTING INFLUENCES


Critical Appraisal

  • CONTROL GROUP ACCEPTABLE

  • Definition of controls

  • Source of controls

  • Matching and randomization

  • Comparable characteristics


Critical Appraisal

  • STUDY DESIGN APPROPRIATE TO OBJECTIVES

  • STUDY SAMPLE REPRESENTATIVE

  • CONTROL GROUP ACCEPTABLE

  • QUALITY OF MEASUREMENTS AND OUTCOMES

  • COMPLETENESS

  • DISTORTING INFLUENCES


Critical Appraisal

  • QUALITY OF MEASUREMENTS AND OUTCOMES

  • Validity

  • Reproducibility

  • Blindness

  • Quality control


Critical Appraisal

  • STUDY DESIGN APPROPRIATE TO OBJECTIVES

  • STUDY SAMPLE REPRESENTATIVE

  • CONTROL GROUP ACCEPTABLE

  • QUALITY OF MEASUREMENTS AND OUTCOMES

  • COMPLETENESS

  • DISTORTING INFLUENCES


Critical Appraisal

  • COMPLETENESS

  • Compliance

  • Drop outs and deaths

  • Missing data


Critical Appraisal

  • STUDY DESIGN APPROPRIATE TO OBJECTIVES

  • STUDY SAMPLE REPRESENTATIVE

  • CONTROL GROUP ACCEPTABLE

  • QUALITY OF MEASUREMENTS AND OUTCOMES

  • COMPLETENESS

  • DISTORTING INFLUENCES


Critical Appraisal

  • DISTORTING INFLUENCES

  • Extraneous treatments

  • Contamination

  • Changes over time

  • Confounding factors

  • Distortion reduced by analysis


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


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.).


IS EVIDENCE BASEDMEDICINE DEAD?Trisha GreenhalghProfessor of Primary CareUniversity College London


  • 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


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