Dr. Yasser Ahmed AbdelrahmanLecturer of anesthesia and intensive careAin shams university, Faculty of MedicineJune, 2012

EVIDENCE

BASEDMEDICIN

E

HYPETHESIS

Hypo-ti-thenai To put under or Suppose

HYPETHESIS

observation understanding intuition

HYPOTHESIS TESTING

observation understanding intuition

CLINICAL DECISION

Patient Values

Patientcircumstances

ResearchEvidence

OptimalDecision

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

1. Production of evidence.2. Production of guidelines.3. Implementation of guidelines.4. Evaluation of compliance.

Translational Quantum

Basic Science DiscoveryEarly TranslationPhase I & II Trials

Late TranslationPhase III Trials

Agreement & ProductionPhase IV Trials

Dissemination Adoption

Evidence based Medicine

Steps in Practicing EBM1. Convert the need for information

into an answerable question.2. Track down the best evidence with

which to answer that question.3. Critically appraise the evidence for

its validity, impact, and applicability.

4. 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.

Background questions are typically answered by textbooks.

What modes of ventilation can cause barotrauma?

Foreground questions

Foreground questions ask for specific knowledge about a specific patient with a specific condition.

Foreground questions are typically answered by databases that access the

research literature

Is APRV protective against barotrauma in patients with ARDS?

Differences in Type of ?’s

• “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.

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 Questions

TherapyIn __________________, 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 EBM1. Convert the need for information

into an answerable question.2. Track down the best evidence with

which to answer that question.3. Critically appraise the evidence for

its validity, impact, and applicability.

4. 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

Case Series/Case Reports

Case Control Studies

Cohort Studies

Randomized Controlled Trial

Systematic Review

Meta-analysis

Animal Research

Cause

Prevalence

• STUDY DESIGN APPROPRIATE TO OBJECTIVES

Prognosis

Therapy

Type of QuestionSuggested Best Type of Study

TherapyRCT > cohort > case control > case series

DiagnosisProspective, blind comparison to gold standard

Etiology / HarmRCT > cohort > case control > case series

PrognosisCohort study > case control > case series

PreventionRCT > cohort study > case control > case series

Clinical ExamProspective, blind comparison to gold standard

CostEconomic 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.

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 IIIevidence 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 EBM1. Convert the need for information

into an answerable question.2. Track down the best evidence with

which to answer that question.3. Critically appraise the evidence for

its validity, impact, and applicability.

4. Integrate the evidence with our clinical expertise and our patient’s characteristics and values.

Critical Appraisal

• STUDY DESIGN APPROPRIATE TO OBJECTIVES

• STUDY SAMPLE REPRESENTATIVE

• CONTROL GROUP ACCEPTABLE

• QUALITY OF MEASUREMENTS AND OUTCOMES

• COMPLETENESS

• DISTORTING INFLUENCES

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

oDefinition of controlsoSource of controlsoMatching and randomizationoComparable 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 OUTCOMESoValidityoReproducibilityoBlindnessoQuality 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

oComplianceoDrop outs and deathsoMissing 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

oExtraneous treatmentsoContaminationoChanges over timeoConfounding factorsoDistortion 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