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					實證醫學簡介與教學概念


  柯德鑫 MD, PhD.
  神經科/教學中心
   奇美醫學中心
RELATIONSHIP AMONG CORE
COMPETENCIES FOR HEALTH
PROFESSIONS




               (IOM, Health Professions Education, 2003)
       實證醫學

   是一種診療模式,是結合醫師個人的臨
    床經驗及最新的臨床研究結果來對任一
    病人做出最合理的診斷和治療之一種模
    式,它必然是以病人為中心(patient-
    centered)、以其醫療問題為導向
    (problem-based)的臨床醫學。
   有稱 証據醫學 或 驗証醫學。
What evidence-based medicine is?
           What is
                      “Evidence-based
                       medicine is the
                       integration of
                       best research
                       evidence with
                       clinical expertise
                       and patient
                       values”
                       - Sackett, et al 2001
Evidence-Based Medicine
(EBM)
   The consistent use of current best evidence
    derived from published clinical and
    epidemiologic research in management of
    patients, with attention to the balance of risks
    and benefits of diagnostic tests and
    alternative treatment regimens, taking
    account of each patient’s unique
    circumstances, including baseline risk,
    comorbid conditions and personal
    preferences.
                 健康狀態
            疾病
                   病人
          病態生理變化

                 感覺不適
  診斷條件:
                        病史詢問
  特異性高的發現
  統計上相關性
                   醫師   理學檢查
  相近的病態生理/病理機制          臨時診斷思考

            形成最可能的假設診斷

                          相關的檢驗與檢查


                 證實假設診斷
蔡景仁教授提供
Why need EBM


   EBM deals with the uncertainties of
    clinical medicine and has the
    potential for transforming the
    education and practice of the next
    generation of physicians.
information overloading?
Why need EBM

   Physicians will continue to face an
    exploding volume of literature, rapid
    introduction of new technologies,
    deepening concern about burgeoning
    medical costs, and increasing attention to
    the quality and outcomes of medical care.
   EVERYBODY CAN ACCESS ON-LINE!
Three solutions
Clinical performance can keep up to date:
1 by learning how to practice evidence-
  based medicine ourselves.
2 by seeking and applying evidence-
  based medical summaries generated
  by others.
3 by applying evidence-based strategies
  for changing our clinical behaviour.
    Requirements for the
    practice of EBM:

1. What information is required to resolve the problem
2. Conducting an efficient search of the literature
3. Precisely defining a patient’s problem
4. Selecting the best of relevant studies and applying
   rules of evidence to determine their validity
5. Being able to present to colleagues in a succinct fashion
6. Extracting the message and applying to the patient’s
   problem
How to teach EBM?

   Hard to introduce EBM to staffs in hospitals?
   - The needs to practice EBM, give incentives;
   - Clinicians do practice EBM everyday (with
    uncertain level of evidence), but need to
    modify the practice attitude;
   - Don’t give too many jargons, just make
    them familiar with the practice.
Evidence-based medicine

   Is not brand new in clinical medicine arena;
   Helps you to update your clinical skills
    and knowledge effectively;
   Helps you to give patients state-of-the-art
    care;
   Helps you to win a malpractice case;
   Helps you to claim money back from the
    NHI Bureau (in Taiwan).
 Evidence-based medicine

As a distinctive approach to patient care,
two fundamental principles in EBM:
1. Evidence alone is never sufficient to
   make a clinical decision. Benefits,
   risks, costs, patient’s value.
2. EBM posits a hierarchy of evidence
   to guide clinical decision making.
What evidence-based
medicine is:
The practice of EBM is the integration of
 individual clinical expertise

   with the
 best available external clinical evidence
  from systematic research.
      and
 patient’s values and expectations
What is Evidence-Based
Medicine?
 See a patient
 Ask a question

 Seek the best evidence for that question

 Appraise that evidence

 Apply the evidence

 Monitor the change
Critical Appraisal

   The process of deciding whether a piece of
    research can help you in answering your
    clinical question. Three questions you
    need to ask about any kind of research:
   1. Is it valid?
   2. Is it important?
   3. Is it applicable to the patient?
Evidence-Based Medicine
(EBM)
   Meta-analysis is an overview in which
    uses quantitative methods to summarise
    the results from different clinical trials.

   Odds Ratio describes the odds of an
    experimental patient suffering an adverse
    event relative to a control patient.
    Evaluation of A
    Diagnostic Test
   Sensitivity is the proportion of people with the
    disease who have a positive test.
   Specificity is the proportion of people free of the
    disease who have a negative test.
   Positive Predictive Value (+PV) is the proportion
    of people with a positive test who truly have the
    disease.
   Negative Predictive Value (-PV) is the
    proportion of people with a negative test who are
    free of the disease.
    Evaluation of A
    Diagnostic Test
   SnNout when a sign/test has a high sensitivity, a negative
    result rules out the diagnosis; e.g. the sensitivity of a
    history of ankle swelling for diagnosing ascites is 92%,
    therefore if a person does not have a history of ankle
    swelling, it is highly unlikely that the person has ascites.

   SpPin when a sign/test has a high specificity, a Positive
    result rules in the diagnosis; e.g. the specificity of fluid
    wave for diagnosing ascites is 92%. Therefore, if a person
    has a fluid wave, it is highly likely that the person has
    ascites.
    Evidence-Based Medicine
    (EBM) in Clinical Trial
   Number Needed to Treat (NNT) is the
    number of patients who need to be treated
    to prevent one bad outcome.

   Number Needed to Harm (NNH) is the
    number of patients under treatment that is
    need to develop one bad outcome or adverse
    effect.
    Therapies

   Absolute risk reduction
    – difference in two event rates
    – CER - EER = ARR
   Relative risk reduction
    – proportion of control rate
    – CER-EER / CER = RRR

    *CER: control event rate
     EER: experimental event rate
Therapies

   Number needed to treat
    – number of extra patients you need to
      treat to prevent one bad outcome
    – 1 / ARR = NNT
Therapies

   95% confidence interval
    – range within which the true value falls
      with 95% confidence

    – use computer (e.g. CATMaker)
Occurrence of death, stroke, or other major
complications


                                                       Number
                       Adverse events                 needed to
                                                      treat NNT

Patient status at    Placebo     Active
                                          RRR   ARR   1/ARR=NNT
      entry             P          A


Prior target organ
                       .22        .08     64%   .14    1/.14=7
     damage


 No prior organ
                       .10        .04     60%   .06    1/.06=17
    damage
THERAPY WORKSHEET
Are the valid results of this randomized trial important?



 SAMPLE CALCULATIONS:
                                     Relative Risk       Absolute Risk      Number Needed
      Occurrence of diabetic
                                      Reduction           Reduction            to Treat
           neuropathy
                                         RRR                 ARR                 NNT

                      Intensive
 Usual Insulin
                       Insulin
 Control Event                        CER - EER
                    Experimental                          CER - EER               1/ARR
     Rate                               CER
                     Event Rate
     CER
                         EER


                                   9.6% - 2.8% = 71%   9.6% - 2.8% = 6.8%   1/6.8% = 15 pts,(11
     9.6%               2.8%
                                          9.6%            (4.3% to 9.3%)          to 23)
Six guides to distinguish useful from
useless or even harmful therapy


  1. Was the assignment of patients to treatments really
     randomized?
  2. Was all clinically relevant outcomes reported?
  3. Were the study patients recognizably similar to your own?
  4. Were both clinical and statistical significance considered?
  5. Is the therapeutic maneuver feasible in your practice?
  6. Were all patients who entered the study accounted for its
     conclusion?
  Are the results of this systematic
  review of therapy valid?

1. Is this a systematic review of randomized trials?
2. Does it include a methods section that describes:
(a) finding and including all the relevant trials?
(b) assessing their individual validity?
3. Were the results consistent from study to study?
(4. Were individual patient data used in the analysis
     (or aggregate data)? )
Are the recommendations in
this guideline valid?
1. Did its developers carry out a
    comprehensive, reproducible literature
    review within the past 12 months?
2. Is each of its recommendations both
    tagged by the level of evidence upon
    which it is based and linked to a
    specific citation?
Critical appraisal

   Prognosis studies
   Harm/etiology studies
   Clinical decision analysis
   Economic analysis
An effective teacher

   Cares about :
    - Why you teach this course?
    - Whom the learners are?
    - What are you going to teach?
    - How would you teach?
How to teach EBM

My Philosophy:
 Meet the needs of the audience;

 Make them feeling comfortable with
  EBM on first encounter;
 Guide them to explore farther the
  skills of EBM afterwards.
How to teach EBM?

   Hard to introduce EBM to staffs in hospitals?
   - The needs to practice EBM, give incentives;
   - Clinicians do practice EBM everyday (with
    uncertain level of evidence), but need to
    modify the practice attitude;
   - Don’t give too many jargons, just get
    familiar with the practice.
T
    Thank you for your attention !

				
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posted:9/22/2012
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