Evidence Based Medicine

By Mohamed Elreedy

Resident of Anesthesiology

Ain Shams University Hospitals

Mohamed a 60 years old patient medically free, admitted to ICU post-operatively after major abdominal surgery. Post operatively he was admitted to surgical ICU. After 24 hours from ICU admission the patient started to suffer from low grade fever 37.5°C,tachycardia (100 beat/min) and increased leucocytes count (16000 cells/mm³). Over the last 12 hours his urine output was less than 0·5 mL/kg/hour. Pre-operatively he had neither history of renal disease nor any previous renal condition and his urine output was adequate. You though to better start low Dopamine dose infusion (< 3 μg/kg/min) in an attempt to restore and maintain his renal blood flow and urine output. You decide to research this question before proceeding on.

Let’s Read This!!!

The most common definition of EBM is taken from Dr. David Sackett.

EBM is the integration of clinical expertise, patient values, and the best evidence into the decision making process for patient care.

The evidence, by itself, does not make a decision for you.

Evidence-based medicine requires new skills of the clinician, including efficient literature-searching, and the application of formal rules of evidence in evaluating the clinical literature.

What Is Evidence Based Medicine?

Production of evidence through research and scientific review.

Production and dissemination of evidence-based clinical guidelines.

Implementation of evidence-based, cost-effective practice through education and management of change.

Evaluation of compliance with agreed practice guidance and patient outcomes – this process includes clinical audit.

Elements Of EBM

It may have been started………

In the current era, they were consolidated and named EBM in 1992

The subsequent rapid spread of EBM has arisen from 4 realizations and is made possible by 5 recent developments.

Why the sudden interest in EBM?

The realizations areThe realizations are1. Our daily need for valid information.

2. The inadequacy of traditional sources for this information

3. The disparity between our diagnostic skills and clinical judgment.

4. Our inability to afford more than a few seconds per patient for finding and assimilating this evidence

1. Development of strategies for efficiently tracking down and appraising evidence.

2. The creation of systematic reviews.

3. The creation of evidence-based journals of secondary publication.  

4. The creation of information systems for bringing the foregoing to us in seconds.

5. The identification and application of effective strategies for life-long learning and for improving our clinical performance.

However, 5 developments have permitted us to However, 5 developments have permitted us to turn this state of affairs aroundturn this state of affairs around

Systematic reviews are a way of summarizing research evidence.

High-quality systematic reviews take great care to find all relevant studies published and unpublished, assess each study, synthesize the findings from individual studies in an unbiased way and present a balanced and impartial summary of the findings with due consideration of any flaws in the evidence.

Not all published systematic reviews have been produced with meticulous care

What are systematic reviews?

How do we actually practice EBM?

EBM comprises 5 steps, they are:1. Converting the need for information into an answerable question

2. Tracking down the best evidence with which to answer that question

3. Critically appraising that evidence

4. Integrating the critical appraisal with our clinical expertise

5. Evaluating our effectiveness and efficiency in executing Steps 1-4 and seeking ways to improve them both for next time.

Modes of Practicing Medicine

We can identify 3 different "modes" of practice:

For the conditions we encounter every day “Appraising" mode.

For the conditions we encounter less often “Searching" mode.

The problems we're likely to encounter very infrequently “Replicating" mode.

In a survey of UK GPs

Can clinicians actually practice EBM?

Getting To The Evidence Quickly

In a busy (180+ admissions per month) in-patient medical service

Electronic summaries of evidence previously appraised

Summary journals to working rounds

10 seconds

25 seconds

No such evidence is available from randomized trials

This is because no investigative team or research granting agency has yet overcome the problems of sample-size, contamination, blinding, ethical concerns and long-term follow-up which such a trial requires.

Does providing evidence-based care improve outcomes for patients?

Myocardial infarction survivors prescribed Aspirin or Beta-blockers have lower mortality rates than those who aren't prescribed these drugs.

Where clinicians use more Warfarin in stroke unit referrals, stroke mortality declines by >20%.

For positive examples

Patients undergoing carotid surgery despite failing to meet evidence-based operative criteria, when compared with operated patients who meet those criteria, are more than 3 times as likely to suffer major stroke or death in the next month.

For Negative examples

Meta-analysis is a statistical technique for combining the findings from independent studies.

The validity of the meta-analysis depends on the quality of the systematic review on which it is based.

Good meta-analyses aim for complete coverage of all relevant studies, look for the presence of heterogeneity and explore the robustness of the main findings using sensitivity analysis.

What Meta-analysis?

OpponentsProponents

EBM is "old hat". The new focus on EBM "formalizes" that "old hat"

EBM is "cook book medicine". EBM should be one part of the process.

EBM is the mindless application of population studies to the treatment of

the individual.

The last step in the EBM process is to decide whether or not the information

and results are applicable to your patient and to discuss the results with

the patient.

Often there is no randomized controlled trial or "gold standard" in the literature to address the clinical

question.

Clinicians might consider the "evidence pyramid”

Great difficulty in getting access to the evidence

Librarians can help

Evidence-based medicine Issues

Critical appraisal is the process of systematically examining research evidence to assess its validity, results and relevance before using it to inform a decision.

Randomized controlled trials and systematic reviews are not automatically of good quality and should be appraised critically.

What’s Critical Appraisal?

It reinforces the need for communication skills.

It provides an effective life-long learning.

Identifying the questions for which no satisfactory evidence exists.

It provides a common language.

What are the other uses of EBM?

The EBM Process (based on example on http://www.hsl.unc.edu/Services/Tutorials/EBM/Question.htm)

The Patient1. Start with the patient: a clinical problem/ question arises out of the care of the patient.

The Question2. Construct a well-built question derived from the case.

Mohamed a 60 years old patient medically free, admitted to ICU post-operatively after major abdominal surgery. Post operatively he was admitted to surgical ICU. After 24 hours from ICU admission the patient started to suffer from low grade fever 37.5°C,tachycardia (100 beat/min) and increased leucocytes count (16000 cells/mm³). Over the last 12 hours his urine output was less than 0·5 mL/kg/hour. Pre-operatively he had neither history of renal disease nor any previous renal condition and his urine output was adequate. You though to better start low Dopamine dose infusion (< 3 μg/kg/min) in an attempt to restore and maintain his renal blood flow and urine output. You decide to research this question before proceeding on.

1. Patient or problem

2. Intervention, prognostic factor, or exposure

3. Comparison

4. Outcomes

Anatomy of a Good Clinical Question

Patient / Problem Early renal dysfunction

Intervention Dopamine

Comparison, if any None, placebo

OutcomeReducing the risk of renal failure

Type of question

DiagnosisHow to select and interpret diagnostic tests

TherapyHow to select treatments to offer patients that do more good than harm

PrognosisHow to estimate the patient's likely clinical course over time and

anticipate likely complications of disease

Harm/EtiologyHow to identify causes for disease (including iatrogenic forms)

Types Of Studies

As you move up the pyramid the amount of available literature decreases, but increases in its relevance to the clinical setting.

The type of question is important and can help lead you to the best study design

Type of QuestionSuggested best type of Study

TherapyRCT>cohort > case control > case series

Diagnosisprospective, blind comparison to a 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

Our Question

For our patient, the clinical question might be:

In critically ill patients with early renal dysfunction, is low dopamine administration effective in reducing the risk of renal failure?

The Literature Search

Large databases such as MEDLINE will give you access to the primary literature

For this question, we have chosen MEDLINE as our resource. MEDLINE is the most comprehensive resource for health-related literature searches and is accessible to everyone through PubMed

The Resource

3. Select the appropriate resource(s) and conduct a search

Formulate Your Strategy

Patient PopulationCritically ill patients

with early renal dysfunction

Early renal dysfunction limited to critically ill patients

InterventionDopamineDopamine

Comparison (if any)None or placebo

OutcomeReducing the risk of

renal failureReducing the risk of renal

failure

Type of QuestionTherapy

Type of StudyRCTLimit to randomized

controlled trial as publication type

Constructing a well-built clinical question can lead directly to a well-built search strategy

Step 1: Search each important concept separately .

Using MeSH search (Medical Subject Heading) to be sure it found the appropriate MeSH Terms and Text Words.

Your Key Words are:

1.Renal Dysfunction

2.Low dopamine dose

Step 2: Combine the separate sets of articles

You need to combine them to identify those articles that contain the 2 terms. In PubMed you must use the "#".

Step 3: Limit the results to the

appropriate publication type and human

Our Limits:

1.RCT

2.Humans

Review the results

Review the titles and abstracts to identify potentially relevant articles

Evaluating the Results

The evaluation4.Appraise that evidence for its validity (closeness to the truth) and applicability (usefulness in clinical practice)

There are three basic questions that need to be answered for every type of study: 1.Are the results of the study valid? 2.What are the results? 3.Will the results help in caring for my patient?

The information is found primarily in the study methodology

Once you have determined that the study methodology is valid, you must examine the results and their applicability to the patient. Clinicians may have additional concerns such as whether the study represented patients similar to his/her patients, whether the study covered the aspect of the problem that is most important to the patient, or whether the study suggested a clear and useful plan of action

Are the results of this therapy study valid?

1. Was the assignment of patients to treatment randomized?

2. Were all the patients who entered the trial properly accounted for at its conclusion?

3. Were patients analyzed in the groups to which they were (originally) randomized?

4. Were patients, clinicians, and study personnel "blind" to treatment allocation?

5. Were the groups similar at the start of the trial?

6. Aside from the experimental intervention, were the groups treated equally?

7. Are the results of this study valid?

Return to the Patient

The patient5. Return to the patient -- integrate that evidence with clinical expertise, patient preferences and apply it to practice

Evaluate Your Performance

Self-evaluation6. Evaluate your performance with this patient

Now what’s BETs (Best Evidence Topics)?

Physicians need rapid access to the best current evidence on a wide range of clinical topics, But where to find it?

BETs were developed in the Emergency Department of Manchester Royal Infirmary, UK, to provide rapid evidence-based answers to real-life clinical questions.

BETs are designed for the working clinician and therefore do not normally search the "grey literature"