by Christine Dollaghan
How do you feel when you hear the words "evidence-based practice" or
"EBP"? In talking about EBP with clinicians, colleagues, and students
during the past few years, I've seen reactions ranging from euphoria
(admittedly rare) to outrage (thankfully also rare).
The most common feeling, however, seems to be a mixture of curiosity
and anxiety: curiosity about the reasons for the "buzz" about EBP, and
anxiety over the possibility that EBP will turn out to be just one more
unrealistic demand placed on already over-burdened professionals. By a
brief description of some of the myths and realities of EBP, I hope to
encourage the "EBP-curious" to feel considerably more confident about
what this perspective on clinical decision-making can offer to those
willing to keep both euphoria and outrage at bay.
Myths and Definitions
By now, most people are familiar with the definition of EBP as
". . .the conscientious, explicit, and judicious use of current best
evidence in making decisions about the care of individual patients . .
. [by] integrating individual clinical expertise with the best
available external clinical evidence from systematic research" (Sackett
et al., 1996). However, some parts of this definition ("best available
external clinical evidence from systematic research") seem to get a lot
more attention than others ("individual clinical experience"). So the
first myth about EBP that needs to be dispelled is the idea that
evidence from systematic research is the only acceptable basis for
clinical decision-making. As Guyatt and colleagues (2000) note,
"evidence is never enough;" the EBP framework acknowledges that the
experiences, values, and preferences of ourselves and our patients can
and should contribute to our clinical decisions.
EBP does require us, however, to identify and make use of the
highest quality scientific evidence as one component of our efforts to
provide optimal patient care. Unfortunately, this worthy goal is linked
to another myth about EBP: namely, that it requires clinicians to spend
hours each week scouring the hundreds of newly published articles and
textbooks for nuggets of evidence "gold." No practitioner has the time
and few have either the inclination or the expertise for such a task.
Instead, proponents of EBP (e.g., Sackett et al., 2000) suggest
several strategies by which clinicians can find the relatively rare
evidence that is of sufficient quality to influence clinical practice,
while at the same time ignoring, or better yet avoiding altogether, the
deluge of weaker evidence. These authors suggest that practitioners are
likely to have no more than 30 minutes per week to devote to locating
and evaluating evidence; thus, their suggestions are oriented around
this minimal time investment.
One of their suggestions is that practitioners focus their limited
time on evidence from "high-yield" sources. Such sources contain
evidence that is current, of high quality (according to the criteria
described below), and directly applicable to clinical practice. Sackett
et al. (2000; 1999) urge us to examine journals and evidence compilers
such as those described below to identify the one(s) most likely to
contain quality evidence, and to limit ourselves to these rather than
devoting time to low-yield and/or dated sources such as traditional
textbooks and journals oriented to "basic science." The de-emphasis in
EBP on evidence sources that are difficult to update rapidly, such as
traditional textbooks, derives from the explicit acknowledgment that
what we "know" at any point is virtually guaranteed to change as
science progresses, so our efforts to identify current best evidence
should focus on the most contemporary sources.
Similarly, the EBP orientation disavows the longstanding belief that
all basic science findings are relevant to clinical practice. The
goals, designs, and methods of studies aimed at providing strong
answers to questions about clinical practice are in some respects quite
different from those of studies aimed at understanding basic mechanisms
of disease. In the EBP framework, evidence from studies of basic
mechanisms plays a similar role to evidence derived from personal
experience or the opinions of authorities; all of these sources can
provide fruitful "leads," but these must be followed up in subsequent
studies explicitly designed to address questions about clinical
practice.
Internet access to high-yield sources and sites exponentially
decreases the time needed to locate current best evidence. For example,
www.guideline.gov,
a free resource sponsored by the Agency for Healthcare Research and
Quality, provides a compilation of evidence reviews and practice
guidelines published by a variety of groups on a wide range of topics.
Clinicians can search the Web site for information on specific topics
or browse for guidelines in category headings. Although the bulk of
information concerns medical conditions, the site contains a number of
guidelines on such topics as hearing screening, autism, attention
deficit hyperactivity disorder, learning disorders, and others,
providing busy practitioners with rapid access to a synthesis of
information on screening, diagnosis, treatment, and prognosis.
Individuals can also register to receive free weekly e-mail updates
listing new or revised guidelines, and those of interest can be
accessed in a matter of seconds. Similarly, PubMed (www.ncbi.nlm.nih.gov)
is a free site sponsored by the National Library of Medicine, in which
users can search for specific information from among literally millions
of biomedical and other life science citations, and in many cases, the
complete article can be accessed online. The PubMed site has a number
of extraordinarily helpful features, such as a "cubby" in which an
individual user can store results from previous searches and ask
"what's new" on that topic at a later date, again in a matter of
seconds. PubMed also has a "clinical query" search, specifically
designed to allow searches concerning diagnosis, therapy, etiology, and
prognosis for a given condition using research methodology filters that
increase the likelihood that results will be directly relevant to
clinical practice. Finally, sites such as the Cochrane Library (www.update-software.com/cochrane) develop and report systematic evidence reviews on a wide range of topics. These abstracts are available at no charge.
The availability of millions of articles and tens of sites
containing evidence makes it easy to debunk a third myth about EBP:
namely, that clinicians can or should be able to "stay current" on
every aspect of clinical practice at all times. Instead, Sackett et al.
(2000) assert that we seek evidence mainly when we have specific
questions about specific patients, disorders, or procedures.
Formulating a specific question (e.g., "Compared to direct,
clinician-administered therapy, are parent-administered programs
effective treatments for 3-year-olds with specific language deficits?")
makes it much easier to zero in on what will usually be a relatively
small set of articles. These can then be scanned rapidly to determine
whether their quality appears sufficiently high to warrant a full
reading. Day-to-day clinical activity will often proceed on the basis
of our existing knowledge and experience; EBP implies not that we upend
everything that we think we know, but rather that we upgrade our
knowledge base in response to particular clinical questions in the
explicit, judicious, and conscientious manner described in the
definition of EBP.
Critical Appraisal
Evaluating evidence quality depends on a process of critical
appraisal, which has been described by a number of authors working in
EBP but has been applied only rarely in the literature on communication
disorders (e.g., Yorkston et al., 2001). A myth about critical
appraisal is that only people who have completed years of specialized
study can do it. In fact, Sackett et al. (2000) describe critical
appraisal in some detail, and worksheets for evaluating systematic
reviews and articles concerning studies of diagnosis, treatment,
prognosis, and harm can be found in the section titled "Teaching
Materials" at www.cebm.utoronto.ca.
Some of the criteria will be familiar to clinicians (e.g., Were
there statistically significant differences between treated and
untreated groups? Were the outcome measures valid and reliable?) but
others are less familiar, being more specifically tied to studies
addressing clinical questions (e.g., Were patients assigned randomly to
groups? Were evaluators blinded to group assignment? Were the group
differences large or practically significant?). The many excellent
sources of accessible information on critical appraisal, including
clear and concise self-tutorials (e.g., at www.poems.msu.edu/InfoMastery)
make it possible for interested individuals to learn to evaluate
evidence quality at whatever level of intensity or commitment they
choose.
Familiarity with the process of critical appraisal allows us to
reject the myth that studies with certain designs, in particular
randomized controlled trials (RCTs) of treatment, always provide high
quality evidence. Like any other type of study, RCTs can be designed
and conducted well or poorly; only those studies that meet the critical
appraisal criteria can yield strong evidence concerning treatment. By
applying the critical appraisal criteria, we identify the strengths and
weaknesses in all kinds of studies, providing a principled basis for
resolving disagreements about the optimal approaches to client care.
Because few studies meet all of the critical appraisal criteria,
reasonable people can disagree about the quality of evidence from a
particular study, making it important for individuals to think
independently about the validity, importance, and precision of results
from empirical studies as a prelude to applying them to clinical care.
In reality, EBP is neither the panacea nor the bugaboo that its
mythology has suggested. Rather, EBP offers us a framework and a set of
tools by which we can systematically improve in our efforts to be
better clinicians, colleagues, advocates, and investigators-not by
ignoring clinical experience and patient preferences but rather by
considering these against a background of the highest quality
scientific evidence that can be found.
Christine Dollaghan is a professor in the
Department of Communication Science and Disorders at the University of
Pittsburgh. She is chair of the ASHA Research and Scientific Affairs
Committee, that has prepared a technical report on evidence-based
practice in communication disorders which is currently undergoing
review. Contact her by e-mail at dollagha@csd.pitt.edu.