Applying 'technology assessment' and 'evidence based medicine' theory to interventional radiology. Part 1: Suggestions for the phased evaluation of new procedures

Evidence-based Practice in Radiology: Steps 3 and 4—Appraise and Apply Interventional Radiology Literature

When introducing new interventional radiology techniques or devices, it is important to learn from previous experiences and to remember that there are numerous examples of new techniques that were initially enthusiastically promoted and then subsequently abandoned when early promise was not realized. Appropriateness of new or established interventional radiology techniques to specific clinical conditions must be determined from clinical experience, from communication with experts in the field and/or careful review of available medical literature, and on an individual patient basis by means of review of clinical notes and diagnostic imaging studies. Several paradigms for evidence-based practice (EBP) exist. One model proposes that a central specialized process involving academic centers should primarily construct valid guidelines to direct practice at all levels of medical practice ("top-down" model). An alternative model integrates "the best research evidence with clinical expertise and patient values" ("bottom-up" model). This article will focus on the bottom-up model and describe the use of EBP by individual practitioners or groups of practitioners in optimizing literature review and critical appraisal. EBP is applied to two scenarios as a means of deciding the appropriateness of introducing interventional radiology techniques in a community hospital setting. The authors will also briefly discuss other applications for EBP techniques in interventional radiology, including development of practice guidelines or policy to ensure appropriate and safe practices.

Finding evidence-based answers to practical questions in radiology: which patients with inoperable hepatocellular carcinoma will survive longer after transarterial chemoembolization?

To some, evidence-based practice (EBP) means the identification of centers that produce evidence reports and technology assessments to support guideline development. To others, EBP is the best research evidence integrated with clinical expertise and patient values. Inherent in the first approach is the implication that only central academic organizations can produce valid, reliable analyses of existing literature, which will then be distributed to ordinary practitioners. The second approach implies that ordinary practitioners can learn to use a stepwise approach and a preprepared set of rules and tools to effectively find the best current literature, appraise it, and then apply local circumstances to these rules and tools in their hospital. Paul Glasziou, director of the Centre for Evidence-based Practice in Oxford, England, has coined the phrases top-down EBP and bottom-up EBP to describe these approaches. In this article, the authors describe how knowledge gaps in an ordinary radiology practice can be addressed by using stepwise bottom-up EBP techniques. The following clinical scenario is used: Your hospital's recently appointed chief hepatobiliary surgeon questions the use of transarterial chemoembolization for inoperable hepatocellular carcinoma because of his concerns after reading a recent review article suggesting that there is no clear survival benefit to using this procedure. What would you do? Here is how the authors would do it.

Abdominal aortic aneurysms: elective endovascular repair versus conventional surgery--evaluation with evidence-based medicine techniques

PURPOSE

To use evidence-based techniques to compare elective open surgical repair of abdominal aortic aneurysms with endovascular repair by means of stent placement.

MATERIALS AND METHODS

A focused clinical question formed the basis of a literature search. Evidence-based criteria were used to appraise and assign a "level of evidence" to retrieved articles. The following data were determined from the best studies: systemic, local, and/or vascular complications; graft failure rates; blood loss; mortality; length of intensive care and/or hospital stay; mid- and long-term outcomes; cost of endovascular repair versus that of surgery; and eligibility for endovascular repair. Absolute risk reductions and/or increases and numbers needed to treat or harm were calculated.

RESULTS

The best current evidence came from 22 studies, which showed that there is slight, if any, difference between mortality rates of endovascular repair and surgery. Hospital and/or intensive care stay is shorter, blood loss less, and systemic complications fewer (numbers needed to treat, two to 12) with endovascular repair. Some authors reported a significant increase in local and/or vascular complications with endovascular repair (numbers needed to harm, two to six). Graft failure is significantly more common with endovascular repair (numbers needed to harm, four), and substantive adjunctive interventions are needed. Endovascular repair is more expensive than surgery.

CONCLUSION

Elective endovascular repair has short-term benefits compared with surgery. There is slight, if any, difference in mortality. Endovascular repair costs more than surgery. At follow-up, surgical grafts performed better.

Research publications in vascular and interventional radiology: research topics, study designs, and statistical methods

PURPOSE

Statistical analysis is the universal language of medical research and is a vital tool for communicating the results of vascular and interventional radiology (VIR) procedures. Major articles in two radiology journals were surveyed to characterize the research topics, study designs, and statistical methods seen in recent VIR research publications.

MATERIALS AND METHODS

The authors retrospectively reviewed 130 major clinical VIR articles published from July 2000 to June 2001: 72 articles (55%) from JVIR and 58 articles (45%) from RADIOLOGY: Articles were categorized by research topic and study design. Data were collected on the statistical methodology of each article.

RESULTS

Research topics included vascular intervention in 65 of 130 articles (50%), nonvascular intervention in 26 (20%), vascular imaging in 23 (18%), biopsy in nine (7%), and other topics in seven (5%). Study design was descriptive in 87 studies (67%), comparative in 39 studies (30%), and involved secondary data analysis in four studies (3%). Of 126 primary clinical studies, outcome was cross-sectional (assessed at a single time point) in 40 studies (32%) and longitudinal (measured over time) in 86 studies (68%). Median sample size was 61. Basic tests of association (t-test, chi(2) test, etc.) were used in 71 articles (56%) and advanced tests of association (regression analysis) were presented in 25 (20%). Survival analysis was applied in 34 articles (27%). Decision statistics such as sensitivity/specificity were not used commonly (12%). Confidence intervals and power calculations were reported infrequently (15% and 7%, respectively).

CONCLUSIONS

VIR publications focus on time-dependent outcomes after therapeutic interventions. Readers should understand basic tests of association and survival analysis--these include only 20 named statistical tests.

Evidence-based radiology: a new approach to the practice of radiology

In this review, the principles of evidence-based health care and their application to radiology are discussed. Evidence-based health care involves the more formal integration of the best research evidence with clinical expertise and explicit acknowledgment of patient values in clinical decision making, as compared with conventional practice. Recently, many health care disciplines have adopted the principles and practice of evidence-based health care. In radiology, including its diagnostic and interventional aspects, these developments have received limited attention. This review of evidence-based health care could, therefore, be useful to radiologists at any stage of their training or career, to encourage the practice of evidence-based radiology. The development of evidence-based health care is described, and evidence-based health care and evidence-based radiology are defined. The importance of evidence-based health care as a new approach to the practice of medicine and its importance for transdisciplinary collaboration are discussed. The skills required to practice evidence-based radiology are identified, and the roles of evidence-based radiology in radiologic practice, education, and research are discussed.