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Real Doctors (Life Makers)  |  Clinical  |  Tools of the trade  |  EVIDENCE BASED MEDICINE MADE EASY « previous next »
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« on: /November/ 22, 2005, 08:15:34 PM »

Patient Care Model

The most common definition of EBM is taken from Dr. David Sackett. EBM is "the conscientious, explicit and judicious use of current best evidence in making decisions about the care of the individual patient. It means integrating individual clinical expertise with the best available external clinical evidence from systematic research." (Sackett D, 1996)

EBM is the integration of clinical expertise, patient values, and the best evidence into the decision making process for patient care. Clinical expertise refers to the clinician's cumulated experience, education and clinical skills. The patient brings to the encounter his or her own personal and unique concerns, expectations, and values. The best evidence is usually found in clinically relevant research that has been conducted using sound methodology. (Sackett D, 2002)

The evidence, by itself, does not make a decision for you, but it can help support the patient care process. The full integration of these three components into clinical decisions enhances the opportunity for optimal clinical outcomes and quality of life. The practice of EBM is usually triggered by patient encounters which generate questions about the effects of therapy, the utility of diagnostic tests, the prognosis of diseases, or the etiology of disorders.

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.

The Steps in the EBM Process

The patient
 1. Start with the patient -- a clinical problem or question arises out of the care of the patient
The question

 2. Construct a well built clinical question derived from the case
The resource
 3. Select the appropriate resource(s) and conduct a search
The evaluation
 4. Appraise that evidence for its validity (closeness to the truth) and applicability (usefulness in clinical practice)

The patient

 5. Return to the patient -- integrate that evidence with clinical expertise, patient preferences and apply it to practice
 6. Evaluate your performance with this patient
Life long learning model

The practice of evidence-based medicine is a process of lifelong, self-directed, problem-based learning in which caring for one's own patients creates the need for clinically important information about diagnosis, prognosis, therapy and other clinical and health care issues.

Instead of routinely reviewing the contents of dozens of journals for interesting articles, EBM suggests that you target your reading to issues related to specific patient problems. Developing clinical questions and then searching current databases may be a more productive way of keeping current with the literature.

Evidence-based medicine "converts the abstract exercise of reading and appraising the literature into the pragmatic process of using the literature to benefit individual patients while simultaneously expanding the clinician's knowledge base." (Bordley DR, 1997)?

Why is EBM important?
Information Needs
Studies of information-seeking habits of physicians, have shown that when asked, physicians reported that their practice generated about 2 questions for every 3 patients. Only 30% of physicians' information needs were met during the patient visit, usually by a colleague. Reasons for not using printed resources included office textbook collections too old, lack of knowledge of appropriate resources, and lack of time to find the needed information. (Covell DG, 1995)

When actually observed, investigators found that physicians had about 5 questions for each patient. 52% of these question could be answered by the medical record or hospital information system. 25% could have been answered by published information resources such as textbooks or MEDLINE. (Osheroff JA, 1991)

However, studies have also shown that when clinicians have access to information, it changes their patient care management decisions.

In 1998, Dr. David Sackett, using an "evidence cart" on rounds, reported that of 71 information searches to answer clinical questions, 37 (52%) confirmed the management decision, but 18 (25%) lead to a new therapy or diagnostic test and 16 (23%) corrected a previous plan. (Sackett D, 1998)

Similar results were report by Crowley et al in 2003. The CAR study showed that of 520 clinical questions for which answers were sought in the medical literature, in 53% of these cases the literature confirmed the management decision, but in 47% of these cases the literature changed the medication, diagnostic test, or prognostic information given to the patient. (Crowley S, 2003)

Is the Evidence Available?

According to G. Michaud, "Most primary therapeutic clinical decisions in 3 general medicine services are supported by evidence from randomized controlled trials. This should be reassuring to those who are concerned about the extent to which clinical medicine is based on empirical evidence. This finding has potential for quality assurance, as exemplified by the discovery that a literature search could have potentially improved these decisions in some cases."  (Michaud G, 1998)

The Study Data: of 145 cases and clinical decisions analyzed:

31 could be supported by a randomized controlled trial 

65 were supported by a head-to-head trial (not a placebo-controlled trial) 

23 were supported by case-control or cohort studies 

4 were supported by case series reports 

22 could not be supported with a study from the literature


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Posts: 613

« Reply #1 on: /November/ 22, 2005, 08:20:21 PM »

The EBM Process

The Patient
 1. Start with the patient: a clinical problem/ question arises out of the care of the patient.
The Question
 2. Construct a well-built question derived from the case.
EBM always begins and ends with the patient. To begin this process, consider the following clinical scenario:

Pauline is a new patient who recently moved to the area to be closer to her son and his family. She is 67 years old and has a history of congestive heart failure brought on by several myocardial infarctions.

She has been hospitalized twice within the last 6 months for worsening of heart failure. At the present time she remains in normal sinus rhythm. She is extremely diligent about taking her medications (enalapril, aspirin and simvastatin) and wants desperately to stay out of the hospital. She lives alone with several cats.

You think she should also be taking digoxin but you are not certain if this will help keep her out of the hospital. You decide to research this question before her next visit.

The next step in this process is to take the identified problem and construct a question that is relevant to the case and is phrased in such a way as to facilitate finding an answer. This is called "constructing a well built clinical question."

Anatomy of a good clinical question

1. Patient or problem

How would you describe a group of patients similar to yours? What are the most important characteristics of the patient? This may include the primary problem, disease, or co-existing conditions. Sometimes the sex, age or race of a patient might be relevant to the diagnosis or treatment of a disease.

2. Intervention, prognostic factor, or exposure
Which main intervention, prognostic factor, or exposure are you considering? What do you want to do for the patient? Prescribe a drug? Order a test? Order surgery? What factor may influence the prognosis of the patient? Age? Co-existing problems? What was the patient exposed to? Asbestos? Cigarette smoke?

3. Comparison

What is the main alternative to compare with the intervention? Are you trying to decide between two drugs, a drug and no medication or placebo, or two diagnostic tests? Your clinical question does not always need a specific comparison.

4. Outcomes
What can you hope to accomplish, measure, improve or affect? What are you trying to do for the patient? Relieve or eliminate the symptoms? Reduce the number of adverse events? Improve function or test scores?

The structure of the question might look like this:

Patient / Problem
 congestive heart failure, elderly
Comparison, if any
 none, placebo
 primary: reduce need for hospitalization; secondary: reduce mortality

For our patient, the clinical question might be:

In elderly patients with congestive heart failure, is digoxin effective in reducing the need for rehospitalization?
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« Reply #2 on: /November/ 27, 2005, 09:27:17 AM »

Type of question

Two additional elements of the well-built clinical question are the type of question and the type of study. This information can be helpful in focusing the question and determining the most appropriate type of evidence.

The most common types of questions related to clinical tasks are:

 how to select and interpret diagnostic tests
 how to select treatments to offer patients that do more good than harm and that are worth the efforts and costs of using them


 how to estimate the patient's likely clinical course over time and anticipate likely complications of disease


 how to identify causes for disease (including iatrogenic forms)
Type of Study

Meta-? ? |
Analysis? |
? ? ? ? ? ? ? ? ? ? ?|
Systematic? ? ? |
Review? ? ? ? ? ?|
? ? ? ? ? ? ? ? ? ? ? ? ? ? ?|
Randomized? ? ? ? ? ? ?|
Controlled Trial? ? ? ? ?|
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? |
Cohort studies? ? ? ? ? ? ? ? ? ? ? |
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? |
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? |
Case Control studies? ? ? ? ? ? ? ? ? ? ? ? |
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? |
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?|
Case Series/Case Reports? ? ? ? ? ? ? ? ? ? ? ? ? ? ?|
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?|
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?|
Animal research/Laboratory studies? ? ? ? ? ? ? ? ? ? ? ? ? |
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?|

This is often referred to as the "evidence pyramid". It is used to illustrate the evolution of the literature.

The base of the pyramid is where information usually starts with an idea or laboratory research. As these ideas turn into drugs and diagnostic tools they are tested in laboratories models, then in animals, and finally in humans. The human testing may begin with volunteers and go through several phases of clinical trials before the drug or diagnostic tool can be authorized for use within the general population. Randomized controlled trials are then done to further test the effectiveness and efficacy of a drug or therapy. As you move up the pyramid the amount of available literature decreases, but increases in its relevance to the clinical setting.

A Meta-analysis will thoroughly examine a number of valid studies on a topic and combine the results using accepted statistical methodology as if they were from one large study. Some clinicians put Meta-analysis at the top of the pyramid because part of the methodology includes critical appraisal of the selected RCTs for analysis.

Systematic Reviews usually focus on a clinical topic and answer a specific question. An extensive literature search is conducted to identify all studies with sound methodology. The studies are reviewed, assessed, and the results summarized according to the predetermined criteria of the review question. The Cochrane Collaboration has done a lot of work in the area of systematic reviews.

Randomized controlled clinical trials are carefully planned projects that study the effect of a therapy on real patients. They include methodologies that reduce the potential for bias (randomization and blinding) and that allow for comparison between intervention groups and control groups (no intervention).

Studies that show the efficacy of a diagnostic test are called prospective, blind comparison to a gold standard study . This is a controlled trial that looks at patients with varying degrees of an illness and administers both diagnostic tests -- the test under investigation and the "gold standard" test -- to all of the patients in the study group.

Cohort Studies take a large population and follow patients who have a specific condition or receive a particular treatment over time and compare them with another group that has not been affected by the condition or treatment being studied. Cohort studies are observational and not as reliable as randomized controlled studies, since the two groups may differ in ways other than in the variable under study.

Case Control Studies are studies in which patients who already have a specific condition are compared with people who do not. They often rely on medical records and patient recall for data collection. These types of studies are often less reliable than randomized controlled trials and cohort studies because showing a statistical relationship does not mean than one factor necessarily caused the other.

Case series and Case reports consist of collections of reports on the treatment of individual patients or a report on a single patient. Because they are reports of cases and use no control groups with which to compare outcomes, they have no statistical validity.

The pyramid serves as a guideline to the hierarchy of evidence available. You may not always find the best level of evidence to answer your question. In the absence of the best evidence, you then need to consider moving down the pyramid to other types of studies.


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« Reply #3 on: /November/ 27, 2005, 09:28:55 AM »

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

Type of Question
 Suggested best type of Study
 RCT>cohort > case control > case series
 prospective, blind comparison to a gold standard
 RCT > cohort > case control > case series
 cohort study > case control > case series
 RCT>cohort study > case control > case series

Clinical Exam

 prospective, blind comparison to gold standard
 economic analysis
For our patient, the clinical question is:

In elderly patients with congestive heart failure, is digoxin effective in reducing the need for rehospitalization?

It is a therapy question and the best evidence would be a randomized controlled trial (RCT). If we found numerous RCTs, then we might want to look for a systematic review.
Brand New
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« Reply #4 on: /March/ 22, 2010, 05:36:47 AM »

Hi friends, I was looking for some information about the garden tools but still unable to find the rarlevent information so it would be great if any one can refer me a page with the required information.
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