DOI: 10.1148/radiol.2442051766
(Radiology 2007;244:331-336.)
© RSNA, 2007
Evidence-based Radiology Series |
Evidence-based Radiology: Review and Dissemination1
L. Santiago Medina, MD, MPH and
C. Craig Blackmore, MD, MPH
1 From the Department of Radiology, Miami Children's Hospital, 3100 SW 62nd Ave, Miami, FL 33155 (L.S.M.); and Department of Radiology, Harborview Injury Prevention and Research Center, University of Washington, Seattle, Wash (C.C.B.). Received October 31, 2005; revision requested December 14; revision received January 16, 2006; final version accepted February 17.
Address correspondence to L.S.M. (e-mail: santiago.medina{at}mch.com).
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ABSTRACT
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Evidence-based radiology (EBR) is an important tool for the practice of radiology. The user of the EBR approach identifies evidence in a systematic fashion and then assimilates information through in-depth, explicit critical review of the best-designed and most recent literature on the subject in question. Clinical decision making is then based on the best current evidence, clinical expertise, and patient values. Substantial progress has been made in the review and dissemination of EBR. Dissemination of EBR within radiology has two critical aspects. The first is increased understanding of the methods required for EBR and of the appropriate use of EBR. The second important component is the dissemination of the data and critical literature reviews necessary to allow use of the EBR approach. Resources available for both EBR methods and EBR data in radiology include societies, journals, medical meetings, Web sites, and textbooks. Although radiology has made important progress in this field in recent years, the specialty is still behind other specialties that have been at the forefront of evidence-based medicine in the past decade.
© RSNA, 2007
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INTRODUCTION
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Evidence-based radiology (EBR) is an important tool for the practice of radiology. However, although there are multiple individuals and institutions aware of the principles of EBR, the dissemination of EBR throughout radiology is still limited. The purpose of this article is to highlight the resources available to radiologists for the understanding of EBR and for the dissemination of EBR data and recommendations. This article focuses on the resources that medical societies, national meetings, Web sites, journals, and textbooks have dedicated to the important principles of evidence-based imaging. This article is part of the Evidence-based Radiology Series published by Radiology. Review of this article and the entire series (1–8) (an additional article, by Raymond and Trop, will appear in the September 2007 issue) would give the reader a more comprehensive understanding of the field of EBR.
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WHAT IS EBR?
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Medical education in Western countries has traditionally focused on local and national experts as sources of knowledge and teaching. Wisdom imparted from these experts through postgraduate medical education and continuing medical education programs forms the foundation of practice. This paradigm has been labeled "eminence-based" radiology and is based on the belief that an expert with a practice devoted to a particular discipline can amass sufficient experience to determine the best approach to clinical imaging problems (9). In contrast, the EBR paradigm is based on the understanding that an individual's experience is biased by practice mix, overemphasis of more recent events, small sample size, and lack of objectivity. Accordingly, best practice should be based on well-designed and well-performed medical research. The user of the EBR approach identifies evidence in a systematic fashion and then assimilates information through in-depth explicit critical review of the best-designed and most recent literature on the subject in question. Clinical decision making is then based on the best current evidence, clinical expertise, and patient values. For radiologists, their radiologic expertise, the ALARA (as low as reasonably achievable) principle, and the values of our patients and referring physicians all have a role to play in integrating best current evidence into robust solutions to clinical problems (9–12).
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WHY IS REVIEW AND DISSEMINATION OF EBR IMPORTANT?
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In the United States in 2001, over 13% of the gross domestic product (and over $1.4 trillion) was devoted to health care. By 2011, the health proportion of the gross domestic product is expected to increase to 17% and health care expenditures are expected to double to $2.8 trillion (13). These numbers are substantially larger than those for all other developed nations. By comparison, the United Kingdom and Australia spend less than 8% of gross national product on health care. In the United States, per capita health care spending is $4672, which is more than twice the amount of these expenditures in the United Kingdom or Australia. However, despite this substantially higher level of spending, it is challenging to identify any indication that medical outcomes are any better in the United States. Life expectancy at birth in the United States in 2000 was 79.7 years for males and 84.6 years for females. This varies little from the life expectancies in other industrialized nations, such as the United Kingdom and Australia (Table 1) (13). The implication is that resources in the United States are not used optimally, although, realistically, medical care in all nations can certainly be improved. Adoption of EBR could help optimize use of health care resources.
The amount of available medical information has also exploded. The National Library of Medicine's PubMed search engine now includes over 15 million citations. It is not possible for a single practitioner to remain up-to-date on the medical literature or even the radiology literature. EBR is a promising method of identifying appropriate information to guide practice and to improve the efficiency and effectiveness of imaging.
Recognition of the importance of EBR can be seen in the definition of general competencies for training of radiologists. The Accreditation Council for Graduate Medical Education has identified six general competencies necessary for all postgraduate medical trainees. These competencies, as they relate to radiology, have been elucidated by a combined committee of the Radiology Residency Review Committee, the American Board of Radiology, and the Association of Program Directors in Radiology. Knowledge of the principles and application of EBR is explicitly included under the competencies of "medical knowledge" and "practice-based learning and improvement" (19). Parallel efforts by the Royal College of Physicians and Surgeons of Canada's Canadian Medical Education Directions for Specialists (known as CanMEDS) include specific inclusion of the ability to critically evaluate the evidence for medical practice decisions in the key competencies expected of physicians.
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PITFALLS IN DISSEMINATION OF EBR
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Two cautionary notes are necessary in discussing dissemination of EBR. First, increasing awareness of the value of the EBR paradigm in radiology has led to a proliferation of information sources. However, the term EBR has come to connote value to such an extent that the term may now be found to be applied to guidelines and consensus recommendations that lack the methodological rigor of a true evidence-based review. Thus, the reader now must be able to assess whether a purported evidence-based review is in fact a recommendation based on a thorough and systematic review of the literature or if it is based on the advice of experts from the more traditional eminence-based approach. This topic was addressed in detail in earlier articles in this series (5,6).
The keystone of the evidence-based imaging approach is to critically assess research data that are provided and to determine whether the information is appropriate for use in answering the EBR question. To understand the value of a recommendation, the reader must discern how the review was accomplished. There is a spectrum in recommendations, from a single expert opinion; to the traditional expert consensus panel; to the expert panel supplemented by review of the relevant literature; to analysis of the literature with grading of strength of evidence; to the full EBR process, with systematic literature review, critical analysis, and meta-analysis and data summary where possible.
The second cautionary note in EBR is that any review is limited by the quality of the underlying research. Unfortunately, published findings from studies in radiology are often limited by bias, small sample size, and methodological inadequacy. Further, the information provided in published reports may be insufficient to allow estimation of the quality of the research. Two recent initiatives, the Consolidated Standards of Reporting Trials (known as CONSORT) (20) and Standards for Reporting of Diagnostic Accuracy (known as STARD) (21) initiatives, aim to improve the reporting of clinical trials and studies of diagnostic accuracy, respectively. However, these guidelines are only now being implemented. This topic has also been addressed in detail in an earlier article in this series (8).
Unfortunately, too commonly, formal critical review and meta-analysis may simply not be possible given the paucity of research evidence. Under such circumstances, practitioners must rely on a combination of what is known through the literature and their own experience or the shared experience of expert panels.
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WHAT RESOURCES ARE AVAILABLE FOR REVIEW AND DISSEMINATION OF EBR?
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Dissemination of EBR within radiology has two critical aspects. The first is increased understanding of the methods required for EBR and of the appropriate use of EBR. The second important component is the dissemination of the data and critical literature reviews necessary to allow use of the EBR approach. Resources available for both EBR methods and EBR data in radiology include societies, journals, medical meetings, Web sites, and textbooks.
To achieve the best dissemination of EBR, a two-way approach needs to be implemented. The two parts can be summarized as "top-down" and "bottom-up" approaches (1). Top-down EBR centers generate primary evidence (original research) and secondary evidence (including guidelines, systematic reviews, and meta-analyses). Bottom-up EBR centers aim to train radiologists to locate, appraise, apply, and evaluate this evidence in their practices, hence minimizing the time from research publication to practice implementation.
Medical and Radiologic Societies
Over the years, several societies for the advancement and dissemination of EBR have been established in medicine and radiology (Table 2). These societies are valuable resources, particularly to aid radiologists in understanding the EBR approach and in advancing EBR methodology. In 1979, the Society for Medical Decision Making was established. Several radiologists were very active in the early years of this society, including Lee Lusted, Barbara McNeil, John Thornbury, and Hal Kundel (22). The mission of the Society for Medical Decision Making (http://www.smdm.org) is to "improve health outcomes through the advancement of proactive systematic approaches to clinical decision making and policy formation in health care by providing a scholarly forum that connects and educates researchers, providers, policymakers, and the public." Their Web site provides very useful education modules on decision analysis and cost-effectiveness. The same Web site has summaries on funding opportunities, masterpiece articles, and repositories on cost-effectiveness and quality of life. Overall, the methods espoused by the Society for Medical Decision Making comprise some of the core aspects of EBR.
The Radiology Alliance for Health Services Research, or RAHSR, is dedicated to the advancement of the principles of EBR in radiology. The RAHSR meets annually in conjunction with the Association of University Radiologists, or AUR. The society has been active in providing review courses on the principles of EBR at the AUR Annual Meeting (http://www.aur.org). The review courses have encompassed the topics of critical assessment of the literature, diagnostic performance of imaging, cost-effectiveness analysis, clinical research, advanced statistics, quality of life, continuous quality improvement, and issues about screening. In February of 2004, Academic Radiology, in conjunction with the RAHSR, published a special report (23) on critical-thinking skills and EBR to increase the dissemination of these concepts to their readership and to the radiology community.
Several more general radiologic societies have established committees to address issues of evidence-based medicine. For example, the American Society of Neuroradiology, or ASNR, has established the Evidence-Based Medicine Committee. This committee has three major roles: (a) First, identify areas where EBR may have a major role in neuroimaging. On the basis of recommendations from the committee, the ASNR has created grants for critical review of the literature and evaluation of the evidence behind neuroimaging studies. The first of these grants has been awarded, with the aim of performing a critical review and meta-analysis of the role of magnetic resonance (MR) spectroscopy in the diagnosis, treatment, and prognosis of brain neoplasms. Future grants on perfusion MR imaging and computed tomography (CT), functional MR, and carotid stent placement are in the works. (b) Second, offer lectures based on the principles of EBR at the annual meeting. Lectures on the role of brain and whole-body screening have been presented at the ASNR Annual Meeting. (c) Third, provide sound evidence to the ASNR membership so the society can move forward in getting the appropriate Current Procedural Terminology codes for reimbursement of neuroradiologic examinations where imaging has made a difference in diagnosis and outcome.
The Radiological Society of North America and its journal Radiology have scientific sessions and article sections, respectively, tailored to health policy and practice and to evidence-based practice of imaging. These presentations serve as important forums for dissemination of research and data for the practice of EBR. Other radiologic societies, including the American Roentgen Ray Society and its journal the American Journal of Roentgenology have similar scientific sessions at their annual meetings and article sections in their journals. Both Radiology and American Journal of Roentgenology have also published series of articles that feature the methodological basis for critical literature review and EBR. In addition, starting in 2003, the European Society of Gastrointestinal and Abdominal Radiologists has included EBR workshops in its annual meeting program. Abstracts on EBR reviews have also been presented after formal peer review.
The Canadian Association of Radiologists and its journal have periodical EBR articles. The journal articles use the National Health Service Centre for Evidence-Based Medicine (University of Oxford, England) hierarchy of validity for studies of diagnosis (24). Evidence is shown in easy-to-follow tables and, at the end of the article, summary comments are provided. Examples of critically appraised topics in the Canadian Association of Radiologists Journal that use EBR can be found in references 25 and 26.
The American Board of Radiology has added, in recent years, critical thinking–type questions to the written examination. The American Board of Radiology has emphasized, in this way, the pivotal role of EBR and the importance for residents learning this field in detail. Inclusion of EBR on the American Board of Radiology examination can be expected to increase resident interest in the topic and aid dissemination.
Another potential source of data for the use of imaging in practice are the Appropriateness Criteria, established in 1993 by the American College of Radiology. In general, the Appropriateness Criteria are based on expert physician panels, rather than on EBR methods, and use serial surveys to achieve consensus in a process called the modified Delphi technique (27). Questionnaires are filled out by the expert reviewers, without the influence of other panel members, by using a nine-point scoring system. Eighty percent agreement is considered a consensus. Although the Appropriateness Criteria do not employ the EBR approach, a critical review of the evidence does form the basis for many of the panel recommendations, and the evidence tables and narrative literature review prepared by the panel leaders may make up a useful starting point for EBR. An advantage of the Appropriateness Criteria is the breadth of the over 170 topics covered. The topic of review methodology has been discussed in detail earlier this series (5).
Centers of EBR
A number of organizations have established centers of EBR, where literature reviews are performed, collected, and disseminated (Table 3). These include government institutions, universities, and private organizations.
The best-known repository for evidence-based medicine reviews is the Cochrane Collaboration (http://www.cochrane.org). Established in 1993, the Cochrane Collaboration is based on the work of epidemiologist Archie Cochrane and promotes teamwork and open communication in defining best practices. The Cochrane Collaboration produces systematic reviews and meta-analyses of interventions throughout medicine. Although the Cochrane Collaboration has a primary focus on clinical trials, and not necessarily on diagnostic tests, the extensive Cochrane library does include a number of reviews relevant to EBR. The Cochrane Collaboration also enables participation for users in developing evidence-based reviews and can therefore serve as a resource for the learning of EBR methods. Each year, the Cochrane Collaboration holds an annual meeting to enable sharing of ideas and communication.
The University of York, England, has the Centre for Reviews and Dissemination (http://www.york.ac.uk/inst/crd/). The center undertakes reviews of research to determine the effects of diagnostic studies and interventions in health and social care. The center maintains various databases, provides an enquiry service, and disseminates results of research to the UK National Health Service decision makers.
The Centre for Evidence-Based Medicine (University of Oxford, England) (http://www.cebm.net) provides information on learning, doing, and teaching EBR. In the learning module, PowerPoint (Microsoft, Redmond, Wash) presentations on systematic reviews, therapy, economic analysis, and decision analysis are presented. In the doing module, Bayes theorem, nomograms, and calculators for likelihood ratio and odd ratios are provided.
The Centre for Evidence-Based Radiology in Ireland (http://www.evidencebasedradiology.net) has a Web site with didactic material tailored to the radiologist interested in learning the principles of EBR as they apply to diagnostic and therapeutic imaging. The Web site initially gives an overview of EBR. This overview is followed by explanation of the process of EBR through the five steps: (a) ask, (b) search, (c) appraise, (d) apply, and (e) evaluate. Both diagnostic testing and interventional procedures are presented with easy-to-follow examples. Pertinent summaries and references are given at the end of the sections. A useful work sheet for critical appraisal of the literature is presented. In the final section, EBR in practice is discussed, with the multiple pros and cons of this approach.
There are also a number of national agencies that prepare evidence-based summaries on various topics. In the United States, the AHRQ funds several evidence-based practice centers (http://www.ahrq.gov/clinic/epcix.htm). In the United Kingdom, the National Health Service has the National Institute for Clinical Excellence, or NICE (http://www.nice.org.uk), which produces evidence-based summaries on various topics. Though neither of these agencies is specifically targeted toward radiology, imaging topics occur in the course of the reviews. For example, AHRQ reviews have included imaging for sinusitis, diagnosis of osteoporosis, and imaging for diagnosis of epilepsy. The NICE has included imaging in their Head Injury and Multiple Sclerosis Guidelines, among other places. These agencies go through rigorous processes with internal and external experts to produce evidence-based summaries that are often also published in the peer-reviewed literature.
Private organizations with a strong interest in evidence-based practice include the Blue Cross and Blue Shield Association Technology Evaluation Center, which is one of the AHRQ-funded evidence-based practice centers. This organization advises the Blue Cross and Blue Shield Association plans on the effectiveness of new technologies in health care. The work of this organization can be found online (http://www.bcbs.com/tec), as well as in the published literature. Imaging reviews by the Technology Evaluation Center include: dual-energy x-ray absorptiometry for osteoporotic fracture risk assessment, MR imaging in breast cancer screening, and MR spectroscopy for suspicion of brain tumor.
A few Web sites provide answers to specific radiology-related questions. The National Public Health Service for Wales provides the Web site ATTRACT (http://www.attract.wales.nhs.uk). Although most of the questions available are for nonimaging issues, several radiology topics are covered, including breast imaging. The UK National Health Services and National Library for Health provide a similar Web service (http://www.clinicalanswers.nhs.uk). The University of Western Ontario, London, Ontario, Canada, has an evidence-based neurology Web site (http://www.uwo.ca/cns/ebn/) that provides answers to questions that pertain to the use of neuroimaging studies.
Textbooks
EBR has slowly moved into the arena of medical textbooks, for dissemination of both methods and literature data. Recent books include the following: Evidence-Based Medicine: How to Practice and Teach EBM, by David L. Sackett and colleagues (12), which provides an overview of the principles and practice of EBR; Evidence-Based Cardiology, by Peter J. Sharis and Christopher P. Cannon (28), which addresses primarily the evidence behind the treatment of several cardiac diseases; and Essential Practice of Surgery: Basic Science and Clinical Evidence, by Jeffrey A. Norton and colleagues (29), which provides tables with the evidence behind several surgical procedures.
A paucity of textbooks in radiology incorporating EBR has been noted over the years. In 2003, Neuroimaging Clinics of North America published an issue on evidence-based neuroimaging (30). This issue provided a systematic approach to EBR in common neurologic disorders, such as stroke, brain neoplasm, Alzheimer disease, and head trauma. In 2006, the textbook Evidence-Based Imaging: Optimizing Imaging for Patient Care was published (16). That text was edited by the authors of the current article and features input from over 50 authors across radiology and related clinical disciplines. The purpose of Evidence-Based Imaging is to provide systematic reviews of clinical issues in imaging, presenting concise summaries of the best imaging choices for patient care, along with evaluations of the strength of the evidence. The 30 chapters cover the most common diseases in the developed world that require imaging, including the major causes of morbidity and mortality. The book is designed to be accessible and easily applied in the clinical setting by practitioners seeking quick information or comprehensive data on the imaging approach best supported by the evidence.
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CONCLUSION
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In conclusion, the practice of radiology is moving into the arena of EBR. Currently, there are multiple media for the dissemination and review of evidence-based imaging at the methodology level, as well as at the level of day-to-day practice applicability. Although radiology has made important progress in the field of evidence-based medicine in recent years, our specialty is still behind other specialties that have been at the forefront of this field in the past decade.
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FOOTNOTES
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Abbreviations: AHRQ = Agency for Healthcare Research and Quality • EBR = evidence-based radiology
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References
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ABSTRACT
INTRODUCTION
