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Perspectives |
1 From the Division of Medical Education, University of Southern California School of Medicine, KAM 211, 1975 Zonal Ave, Los Angeles, CA 90033. Received July 16, 1999; accepted August 24. Address reprint requests to the author (e-mail: bwood@hsc.usc.edu).
Index terms: Decision theory • Education • Perspectives
Initiatives in evidence-based medicine are developing in medical schools and training programs throughout North America and Europe. Physicians and students of medicine have always sought to base medical decisions and actions on the best evidence available. With the ascendancy of randomized trials, we have valid sources available to assist in decision making; on these we can anchor diagnostic, prognostic, and therapeutic decisions. The structured abstract and inclusive literature databases, paired with robust search engines, have improved the availability of information and the ability to search the burgeoning medical literature.
The incorporation of evidence-based medicine into the medical decision-making process is defined by Sackett et al (1) as the "conscientious, explicit, and judicious use of current best evidence in making decisions about the care of individual patients." Using evidence-based medicine, the physician receives useful assistance in making medical decisions through the appropriate identification, evaluation, and application of relevant information. Decisions are made systematically and represent an integration of personal knowledge, experience, and clinical expertise with external evidence gained through focused review of the research.
The two systems must work together. Without the scientific quality of supporting external evidence, clinical practice risks becoming outdated quickly. Without knowledge, experience, and expertise, evidence-based medicine would serve merely as a cookbook, and the value of assessing the individuality of patients' problems would be lost. The practice of good evidence-based medicine assists physicians in the identification and application of the current, most efficacious diagnosis or intervention for the patient's problem.
Traditionally, medical education has used didactic teaching methods that are based on pathophysiology, with information from the experience and expertise of senior master physicians. Paul Gerber, MD, (2) of Dartmouth Medical School, has referred to the method as "eminence-based medicine." The senior physician teaches, and the learners listen, make notes, memorize information, and model themselves after the physician. They are encouraged to seek advice on problem solving and decision making from this person, but they do not often challenge ideas that are set forth.
Friedland (3) has described the four assumptions of traditional medical teaching thus:
1. Individual clinical experience provides the foundation for diagnosis, treatment, and prognosis. The measure of authority is proportional to the weight of individual experience.
2. Pathophysiology provides the foundation for clinical practice.
3. Traditional medical training and common sense are sufficient to enable a physician to evaluate new tests and treatments.
4. Clinical experience and expertise in a given subject area are sufficient to enable the physician to develop clinical practice guidelines.
The assumptions on which evidence-based medicine is built are different, as follows:
1. When possible, clinicians use information derived from systematic, reproducible, and unbiased studies to increase the confidence in the true prognosis, efficacy of therapy, usefulness of diagnostic tests, and so forth.
2. An understanding of pathophysiology is necessary but insufficient for the practice of clinical medicine.
3. An understanding of certain rules of evidence is necessary to evaluate and apply findings from the medical literature effectively.
Does the advent of evidence-based medicine suggest that we should overturn our previous methods? Not at all. Evidence-based medicine represents an evolution in the tools that are used to practice scientific medicine. Furthermore, many dilemmas and problems do not have supporting evidence.
A review of the report by Abraham Flexner in 1910 (4) reveals that, at that time, medicine had evolved from a trade that was taught to individual apprentices by masters to a biomedical science that formed the basis for diagnostic and management decisions. Medical decisions depended on a thorough knowledge of pathophysiology and on thoughtfully acquired clinical judgment. The tools of evidence we now seek serve as an expanding scheme into which our tools of pathophysiology and clinical decision-making experience fit. The tools have been supported by a growing base of scientifically designed studies for the valid evaluation of diagnostic criteria and management decisions, all of which are obtained with a sophisticated and accurate mechanism for searching the literature to identify specific information.
Although the core content of each medical specialty is unchanged, perhaps one of the most important contributions of evidence-based medicine is to move the focus of learning from memorization of facts toward analysis by means of accessing and examining the available information, judging its reliability and validity, and considering the application of the information to the given situation. Decision analysis and the transfer of knowledge or experience are used to assist physicians in situations of uncertainty or novelty.
The concept of evidence-based medicine fits appropriately into the needs of adult learners. Didactic presentation of material is inadequate to fulfill learner needs, as it often represents an individual's compilation of a large body of information and experience, without testing for accuracy or validity; this information may be unrelated to the immediate clinical problems and concerns of the physician and may reflect the bias of the presenter. Mastery of bodies of information in a well-designed curriculum does provide a foundation for knowledge acquisition and use, but information may be misinterpreted or forgotten if it is not reflected upon and applied to solve problems.
Curricula developed to teach children are modeled on a subject-based foundation, whereas the curricula developed to teach adults are modeled on problem identification and problem solving that incorporates evidence-based medicine. Adult learners are highly practical (world-oriented) and choose to learn something because it is needed in their daily activity. Related to this need, adults are self-motivated and self-directed learners. Given the opportunity to effectively add information to their existing expertise, they are eager to develop and build on their experience and to apply what they learn to authentic situations; they then test and revise their work. Adult learners are interested in practical applications of information, which they can model to fit their needs and which they can use to build on their existing knowledge base. With the adult-learner model as a foundation, evidence-based medicine is an extension of the experience of learning and applying knowledge to real-life situations.
The initial step in medical decision making is to gather information and to formulate a solution or to identify a problem for clarification and assessment. The current problem may be defined in relation to a previous experience, or information may be translated to representative cases. The results of a study may or may not be precisely applicable to a specific episode of disease, but the physician is always aware that an individual variation represents a single experience within a wide array of related experiences.
When faced with a medical dilemma, the clinician frames the medical problem, identifies the specific information that is needed, seeks information related to the perceived problem, and evaluates the information for validity and applicability to the given situation. The three components of activities used in evidence-based medicine are decision making (refining the probability of making a differential diagnosis or defining a problem), accessing the appropriate medical information, and assessing the validity of this medical information.
Rosenberg and Donald (5) describe the following four basic components of evidence-based medicine:
1. The first step is recognition of the need for information. The need occurs in the form of a knowledge or experience gap, an inconsistency in information or direction, a question posed by another physician or by the patient, or a curiosity about a disease entity. From this activity, a focused question (or related question) is formulated.
2. The next step is to enter the question into a literature search. The search should be as focused as possible to obtain the most useful information.
3. Once the material has been obtained from the literature, it is assessed for usefulness, applicability, and validity.
4. Last, the results of the search are presented, discussed, or applied to the problem at hand. The wise student will also monitor the results (or outcome) to develop his or her own personal experience.
It is logical to incorporate evidence-based medicine techniques into the early training of physicians to provide them with the fundamental principles of problem and question formulation and of literature appraisal and to prepare them for a practice of life-long learning and seeking of new information. During medical school and residency training, faculty members should serve as role models in how to search the literature and how to interpret valid studies.
Even at the very early stages of medical training, the junior members of a patient-care team can fully participate in decision making and hypothesis testing by incorporating information gleaned from valid clinical studies that were found as the result of well-planned literature searches. They can legitimately challenge incorrect or controversial hypotheses. The use of evidence is appropriately incorporated into the clinical curriculum during routine case conferences, daily rounds, radiology read-out sessions, journal club meetings, and morning reports.
Evidence-based medicine ought to be incorporated early into radiologic training curricula. Our specialty is characterized by a variety of opinions and techniques, which constitute rational approaches to diagnostic medical imaging. Interpretations of the results and observations at imaging vary. The design and steps of a diagnostic study method also vary according to the equipment, experience of the radiologist, and question to be addressed. The great diversity of disease entities to be addressed also adds opportunity for controversy. Radiologists interpret visual information, which is categorized by pattern and which is matched with information and concepts that reside as schemas within the long-term memory. Evidence that is tested and validated by others and that is added to the literature enriches and validates the information and knowledge in our knowledge base.
Teachers of evidence-based medicine should serve as role models for radiologists-in-training because they demonstrate the advantages of being life-long learners, they provide guidance in using the techniques of formulating and defining a problem or question to be answered, and they ensure the development of constant habits of inquiry. The teacher provides the perspective of experience. Residents should always be encouraged to engage in a search for evidence when a controversial point, a misunderstanding, or a knowledge gap is identified.
The most effective learning occurs when specific information is sought and applied to an authentic case or problem at hand. The resident should report the outcome of the search as soon as possible to directly link the practical information to the case problem that was analyzed. Diagnostic dilemmas provide excellent opportunities to expand knowledge and experience by means of searching the literature. When residents present cases in conference, the cases should be accompanied by evidence as often as possible. Journal clubs provide the opportunity to complete exercises in literature evaluation and critique, which includes the evaluation of the study design, the statistical application, the interpretation, and the applicability of study results to a clinical problem. The assignment of a resident to lead the discussion on each topic provides a final arbiter in controversial discussions.
An agenda of keeping abreast of relevant medical literature is suggested by Mendelson (6), who advocates the following strategy:
1. Choose a small number of core journals to regularly browse.
2. Browse before you read; investigate studies that relate to your interests and that provide novel information. This can usually be established by reading the abstract and by determining the relevance of the conclusion presented.
3. Expand your literature surveillance by reading pre-reviewed summaries and evidence-based syntheses. These are contained in journals that publish structured abstracts from articles that are chosen from many major journals; they include commentary about the background, applicability, and limitations of the studies.
4. Use continuing medical education courses to expand your familiarity with the medical literature.
5. Develop expertise in locating specific information to answer focused clinical questions that arise during your work.
6. Establish protected time for critical reading of journals.
Concern has been expressed about the consumption of time in performing searches, but consider the inaccessibility of material, which may be pertinent to your interest, that is buried in the 20,000 medical journals that exist. A recent proliferation of resources has simplified the search process, which has been streamlined with convenient Internet access. MEDLINE (available at http://www.nlm.nih.gov/databases/freemedl.html) continues, to my knowledge, to be the most widely used electronic resource.
Other sources are the American College of Physicians Journal Club (Philadelphia, Pa), which began in 1991 and which was, to my knowledge, the first research digest to provide critical analyses based on rules of study selection and structured abstract development. Evidence-based medicine followed in 1995 to broaden coverage beyond internal medicine. The Cochrane Collaboration (Oxford, England) is a multicenter, international project that attempts to synthesize all controlled trials of health care interventions (7). If there is access to the enormous and excellent medical literature database, will physicians use it? It is always valuable to be able to support your decision with evidence.
References
This article has been cited by other articles:
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  L. S. Medina and C. C. Blackmore Evidence-based Radiology: Review and Dissemination Radiology, August 1, 2007; 244(2): 331 - 336. [Abstract] [Full Text] [PDF]
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D. E. Malone and M. Staunton Evidence-based Practice in Radiology: Step 5 (Evaluate)--Caveats and Common Questions Radiology, May 1, 2007; 243(2): 319 - 328. [Abstract] [Full Text] [PDF]
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M. Staunton Evidence-based Radiology: Steps 1 and 2--Asking Answerable Questions and Searching for Evidence Radiology, January 1, 2007; 242(1): 23 - 31. [Abstract] [Full Text] [PDF]
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M. M. Maher, A. M. McNamara, P. M. MacEneaney, S. J. Sheehan, and D. E. Malone Abdominal Aortic Aneurysms: Elective Endovascular Repair versus Conventional Surgery--Evaluation with Evidence-based Medicine Techniques Radiology, September 1, 2003; 228(3): 647 - 658. [Abstract] [Full Text] [PDF]
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T. The Evidence-Based Radiology Working Group Evidence-based Radiology: A New Approach to the Practice of Radiology Radiology, September 1, 2001; 220(3): 566 - 575. [Abstract] [Full Text] [PDF]
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 C. C. Blackmore The Challenge of Clinical Radiology Research Am. J. Roentgenol., February 1, 2001; 176(2): 327 - 331. [Full Text] [PDF]
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