Expert answer:Evidence Based Practices
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EBML Clinical Practice and Management Practice
Review the Attached document describing the introduction to evidence based clinical
practice at UNC and discuss differences between Evidence-Based clinical practice and
management practice.
Include at least two APA-formatted citation (in-text, as well as the full reference). The
citation may be from course textbooks, assigned readings, or an outside source. Your
initial post must be a minimum of 300 words in length.
Welcome to the Introduction to Evidence-Based
Practice tutorial
This tutorial is intended for any health care practitioner or student who needs a basic introduction to the principles of
Evidence-Based Practice. Upon completion of this self-paced tutorial, you will be able to:
•
•
•
•
define Evidence-Based Practice (EBP)
identify the parts of a well-built clinical question
identify searching strategies that could improve PubMed searching
identify key critical appraisal issues that help determine the validity of a study
How to use this Tutorial
This tutorial includes five major units. We recommend that you go through them in sequence. They will give you an
overview of the Evidence-Based Practice process as well as give you an opportunity to practice with new cases. The
five units are:
1. Overview
What is EBP? provides definitions and
explains the steps in the EBP process.
2. ASK
Asking Clinical Question – introduces you
to a patient, illustrates the anatomy of a
good clinical question, and defines the
types of questions and studies.
3. ACQUIRE
Searching the Literature – constructs a
well-built literature search based on the
PICO and identifies potentially relevant
articles.
4.
APPRAISE
Evaluating the Evidence – identifies criteria
for determining the validity of a study
selected for our case.
5. Practice
Testing your Knowledge – gives you an
opportunity to practice the EBP process
with several new cases.
References
Points you to additional sites for continued
study of the EBP process and provides a
glossary of terms used in EBP.
Feedback
Gives you the opportunity to provide
feedback about this tutorial. We ask that
you take the time to give us your thoughts
and suggestions for improvement. All
comments will be greatly appreciated.
EBP Overview
What is Evidence-Based Practice
(EBP)?
The most common definition of Evidence-Based Practice (EBP) is from Dr. David Sackett. EBP 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)EBP is the integration of clinical expertise, patient
values, and the best research 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 preferences and unique concerns, expectations, and values. The best
research 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 the decision, 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 EBP is usually triggered by patient encounters which generate
questions about the effects of therapy, the utility of diagnostic tests, the prognosis of diseases, and/or the
etiology of disorders.
Evidence-Based Practice 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 EBP Process:
ASSESS
the patient
ASK
the question
ACQUIRE
1. Start with the patient — a clinical problem or question arises from the
care of the patient
2. Construct a well built clinical question derived from the case
3. Select the appropriate resource(s) and conduct a search
the evidence
APPRAISE
the evidence
APPLY:
talk with the
patient
Self-evaluation
4. Appraise that evidence for its validity (closeness to the truth) and
applicability (usefulness in clinical practice)
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
Asking the Well Built Clinical Question
ASSESS
the patient
ASK
the question
1. Start with the patient — a clinical problem or question arises from the
care of the patient
2. Construct a well built clinical question derived from the case
OUR CASE EXAMPLE:
The patient is a 65 year old male with a long history of type 2 diabetes and obesity. Otherwise his
medical history is unremarkable. He does not smoke. He had knee surgery 10 years ago but
otherwise has had no other major medical problems. Over the years he has tried numerous diets
and exercise programs to reduce his weight but has not been very successful. His granddaughter
just started high school and he wants to see her graduate and go on to college. He understands
that his diabetes puts him at a high risk for heart disease and is frustrated that he cannot lose the
necessary weight. His neighbor told him about a colleague at work who had his stomach stapled
and as a result not only lost over 100 lbs. but also “cured” his diabetes. He wants to know if this
procedure really works.
The next step in this process is to take the identified concern or problem and construct a question that is
relevant to the case and is phrased in such a way as to facilitate finding an answer.
Anatomy of a good clinical question: PICO
PICO is a mnemonic that helps one remember the key components of a well focused question. The question
needs to identify the key problem of the patient, what treatment or tests you are considering for the patient,
what alternative treatment or tests are being considered (if any) and what is the desired outcome to promote
or avoid.
P= Patient 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
gender, age or race of a patient might be relevant to the diagnosis or treatment of a disease.
I= 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? Or what factor may influence the prognosis of the
patient – age, co-existing problems, or previous exposure?
C= 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 may not always have a
specific comparison.
O= Outcome:
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?
OUR CASE:
Patient Problem
obese, diabetes type 2, male
Intervention
stomach stapling (gastric bypass surgery; bariatric surgery)
Comparison
standard medical care
Outcome
remission of diabetes; weight loss; mortality
For our patient, the clinical question might be: In patients with type 2 diabetes and obesity, is
bariatric surgery more effective than standard medical therapy at increasing the probability
of remission of diabetes?
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 or study.
Acquiring the Evidence
ACQUIRE
the evidence
3. Select the appropriate resource(s) and conduct a search
In the previous section, we learned how to construct a well-built clinical question. Using that question, we will move
on to the literature search.
For our patient, the clinical question is:
In patients with type 2 diabetes and obesity, is bariatric surgery more effective
than standard medical therapy at increasing the probability of remission of
diabetes? 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.
Constructing a well-built clinical question can lead directly to a well-built search strategy. Note that you may not use
all the information in PICO or well-built clinical question in your MEDLINE strategy. In the following example we did
not use the term “male.” We also did not include the word therapy. Instead we used the Clinical Query for Therapy or
the publication type, randomized controlled trial, to get at the concept of treatment. However, you may consider
the issue of gender later when you review the articles for applicability to your patient.
PICO
Clinical Question
Search Strategy
Patient / Problem
obese, diabetes type 2,
male
diabetes type 2, obesity
Intervention
stomach stapling (gastric
bypass surgery; bariatric
surgery)
bariatric surgery
Comparison (if any) standard medical care
Outcome
remission of diabetes;
weight loss; mortality
Type of Question
therapy
(see below)
RCT
Clinical Query –
Therapy/narrow
or
Limit to randomized
controlled trial as
publication type
Type of Study
Evaluating the Validity of a Therapy
Study
We have now identified current information which can answer our clinical question. The next step is to read
the article and evaluate the study. There are three basic questions that need to be answered for every type
of study:
• Are the results of the study valid?
• What are the results?
• Will the results help in caring for my patient?
This tutorial will focus on the first question: are the results of the study valid? The issue of validity speaks to
the “truthfulness” of the information. The validity criteria should be applied before an extensive analysis of
the study data. If the study is not valid, the data may not be useful.
The evidence that supports the validity or truthfulness of the information is found primarily in the study
methodology. Here is where the investigators address the issue of bias, both conscious and unconscious.
Study methodologies such as randomization, blinding and follow-up of patients help insure that the study
results are not overly influenced by the investigators or the patients.
Evaluating the medical literature is a complex undertaking. This session will provide you with some basic
criteria and information to consider when trying to decide if the study methodology is sound. You will find
that the answers to the questions of validity may not always be clearly stated in the article and that readers
will have to make their own judgments about the importance of each question.
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.
Note: The questions that we used to test the validity of the evidence are adapted from work done at
McMaster University. See the References/Glossary unit: ‘Users’ Guides to the Medical Literature.’
Print the therapy article appraisal worksheet.
Read the following article and determine if it meets the validity criteria. (Click on title to access free
full text).
Mingrone G. Bariatric surgery versus conventional medical therapy for type 2 diabetes. N
Engl J Med. 2012 Apr 26;366(17):1577-85. doi: 10.1056/NEJMoa1200111. Epub 2012
Mar 26. PubMed PMID:22449317.
1. Were patients randomized? The assignment of patients to either group (treatment or control) must be
done by a random allocation. This might include a coin toss (heads to treatment/tails to control) or use of
randomization tables, often computer generated. Research has shown that random allocation comes closest
to insuring the creation of groups of patients who will be similar in their risk of the events you hope to
prevent. Randomization balances the groups for known prognostic factors (such as age, weight, gender, etc.)
and unknown prognostic factors (such as compliance, genetics, socioeconomics, etc.). This reduces the
chance of over-representation of any one characteristic within the study groups.
2. Was group allocation concealed? The randomization sequence should be concealed from the clinicians
and researchers of the study to further eliminate conscious or unconscious selection bias. Concealment (part
of the enrollment process) ensures that the researchers cannot predict or change the assignments of patients
to treatment groups. If allocation is not concealed it may be possible to influence the outcome (consciously
or unconsciously) by changing the enrollment order or the order of treatment which has been randomly
assigned. Concealed allocation can be done by using a remote call center for enrolling patients or the use of
opaque envelopes with assignments. This is different from blinding which happens AFTER randomization.
3. Were patients in the study groups similar with respect to known prognostic variables? The
treatment and the control group should be similar for all prognostic characteristics except whether or not
they received the experimental treatment. This information is usually displayed in Table 1, which outlines the
baseline characteristics of both groups. This is a good way to verify that randomization resulted in similar
groups.
4. To what extent was the study blinded? Blinding means that the people involved in the study do not
know which treatments were given to which patients. Patients, researchers, data collectors and others
involved in the study should not know which treatment is being administered. This helps eliminate
assessment bias and preconceived notions as to how the treatments should be working. When it is difficult or
even unethical to blind patients to a treatment, such as a surgical procedure, then a “blinded” clinician or
researcher is needed to interpret the results.
5. Was follow-up complete? The study should begin and end with the same number of patients in each
group. Patients lost to the study must be accounted for or risk making the conclusions invalid. Patients may
drop out because of the adverse effects of the therapy being tested. If not accounted for, this can lead to
conclusions that may be overly confident in the efficacy of the therapy. Good studies will have better than
80% follow-up for their patients. When there is a large loss to follow-up, the lost patients should be assigned
to the “worst-case” outcomes and the results recalculated. If these results still support the original
conclusion of the study then the loss may be acceptable.
6. Were patients analyzed in the groups to which they were first allocated? Anything that happens
after randomization can affect the chances that a patient in a study has an event. Patients who forget or
refuse their treatment should not be eliminated from the study results or allowed to “change groups”.
Excluding noncompliant patients from a study group may leave only those that may be more likely to have a
positive outcome, thus compromising the unbiased comparison that we got from the process of
randomization. Therefore all patients must be analyzed within their assigned group. Randomization must be
preserved. This is called “intention to treat” analysis.
Want to know more about intention to treat? Watch Explaining the Intention-to-Treat principle with Gordon
Guyatt. 16 minutes.
7. Aside from the experimental intervention, were the groups treated equally? Both groups must be
treated the same except for administration of the experimental treatment. If “cointerventions” (interventions
other than the study treatment which are applied differently to both groups) exist they must be described in
the methods section of the study.
This article meets most of the validity criteria for a therapy article. The next step is to
review the results.
Evaluating the Validity of a Diagnostic
Test Study
Are the results valid?
1. Did participating patients present a diagnostic dilemma?
The group of patients in which the test was conducted should include patients with a high, medium and low
probability of having the target disease. The clinical usefulness of a test is demonstrated in its ability to
distinguish between obvious illness and those cases where it is not so obvious or where the diagnosis might
otherwise be confused. The patients in the study should resemble what might be expected in a clinical
practice.
2. Did investigators compare the test to an appropriate, independent reference standard?
The reference (or gold) standard refers to the commonly accepted proof that the target disorder is present
or not present. The reference standard might be an autopsy or biopsy. The reference standard provides
objective criteria (e.g., laboratory test not requiring subjective interpretation) or a current clinical standard
(e.g., a venogram for deep venous thrombosis) for diagnosis. Sometimes there may not be a widely
accepted reference standard. The author will then need to clearly justify their selection of the reference test.
3. Were those interpreting the test and reference standard blind to the other results?
To avoid potential bias, those conducting the test should not know or be aware of the results of the other
test.
4. Did the investigators perform the same reference standard to all patients regardless of the
results of the test under investigation?
Researchers should conduct both tests (the study test and the reference standard) on all patients in the
study regardless of the results of the test in question. Researchers should not be tempted to forego either
test based on the results of only one of the tests. Nor should the researchers apply a different reference
standard to patients with a negative results in the study test.
Key issues for Diagnostic Studies:
• diagnostic uncertainty
• blind comparison to gold standard
• each patient gets both tests
What are the results?
Study Test
Positive
Study Test
Negative
Reference
Standard
Disease
Positive
True
Positive
False
negative
Reference
Standard
Disease
Negative
False
Positive
True
Negative
Sensitivity: = true positive / all disease positives
measures the proportion of patients with the disease who also test positive for the disease in this study. It is
the probability that a person with the disease will have a positive test result.
Specificity: Specificity = true negative / all disease negatives
measures the proportion of patients without the disease who also test negative for the disease in this study.
It is the probability that a person without the disease will have a negative test result.
Sensitivity and specificity are characteristics of the test but do not provide enough information for the
clinician to act on the test results. Likelihood ratios can be used to help adapt the results of a study to
specific patients. They help determine the probability of disease in a patient.
Likelihood ratios (LR):
LR + = positive test in patients with disease / positive test in patients without disease
LR – = negative test in patients with disease / negative test in patients without disease
Likelihood ratios indicate the likelihood that a given test result would be expected in a patient with the target
disorder compared to the likelihood that the same result would be expected in a patient without that
disorder.
Likelihood ratio of a positive test result (LR+) increases the odds of havi …
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