A database designed for utilization management in diagnostic imaging.

The methods and tools of health services research have been applied to a diverse number of health care areas. Surprisingly, they have been adopted only recently in diagnostic imaging, by a small number of professionals, in response to the severe fiscal constraints and widespread structural changes in the health industry, as well as to a growing concern that the value of social and individual investment in high-cost imaging services could not be validated objectively. As a result of the need for accountability for the use of scarce resources, regulators and payers of health services increasingly demand that a reasoned and objective evaluative process be adopted. To undertake a statistically driven evaluative approach that stands up to objective assessment of methodological rigour, an organized data-collection system is needed. Without this fundamental cornerstone, evaluators are left with little more than anecdotal evidence and professional and personal opinion to guide decision-making. It then becomes difficult to learn from both the successes and failures that are routinely experienced during times of rapid and fundamental change. This article describes the efforts made to integrate health services research in radiology into the routine daily activities and supporting systems of a large academic health system, the Hamilton Health Sciences Corporation and McMaster University Department of Radiology, in an attempt to move in the direction of evidence-based decision-making. The authors hope this will allow others to learn and improve on this work. Radiologists may then move the vast data systems and infrastructure associated with all imaging services to an evidence-based model for managing and guiding the vast resources entrusted to our collective stewardship.

The development of radiology guidelines in Canada, Part 2.

In the second part of a two-part article on the development of Canadian clinical practice guidelines in radiology, the author discusses the implementation of guidelines. The aim is to translate guidelines into practice policies, but nation-wide implementation is difficult because of the regional circumstances and constraints in Canadian health care. One approach to making guidelines more effective tools and preventing conflict is to distinguish between effectiveness (benefit of an intervention under average conditions of use) and efficiency (value of an intervention compared with other things that could be done with the same resources). Clinical practice guidelines are based on effectiveness criteria alone, whereas practice policies can be based on efficiency criteria and are made by those responsible for allocating resources. From an ethical point of view, guidelines have an important feature in common with applied ethics: neither can give the right answer in a situation, but both can indicate the right decision-making process, including who should decide, on what basis, using which process and for what purpose. From a legal standpoint, if the medical community views guidelines as constituting reasonable medical care and jurists see them as a medical and legal norm, they can have significant influence in malpractice litigation. At the last annual meeting of the CAR, the executive committee decided that an integrated national approach to guidelines is needed because of the considerable confusion in this field. It supports the National Framework Development Committee's efforts to set national principles and operating rules for development and implementation. This necessitates an organizational structure consisting of a coordinating group representing consumers, service providers, regulators and funding agencies; multidisciplinary guidelines-development groups; and methodology resource groups.

The development of radiology guidelines in Canada, Part 1.

Canadian clinical practice guidelines are being developed for radiological services. In the first part of a two-part article outlining the history and process of this guidelines development, the author discusses several national and provincial initiatives in this area. A National Partnership for Quality in Health, involving many major physician organizations, was formed in 1990 to promote clinical practice guidelines in Canada. The Canadian Association of Radiologists (CAR) participated in its workshops. CAR decided in 1994 to ask its Task Force on Standards to assume the task of development of appropriateness guidelines in diagnostic imaging. After review of British and US guidelines in radiology, the Task Force decided to develop guidelines tailored to the practice in Canada through interdisciplinary consensus. The CAR subsequently entered into an agreement with the Health Services Research in Radiology Initiative of McMaster University, Hamilton, Ont., to investigate guidelines development, and decided to avoid taking "ownership" of guidelines. Guidelines development is based on the Guidelines Development Cycle of Browman and associates and is condition-based, rather than being all-encompassing or equipment-based. Guidelines developed to date or in progress include those for chest radiography in asymptomatic populations (such as routine health examinations or screening of smokers), for radiographs of foot and ankle injuries, for diagnosis of deep-vein thrombosis and for ultrasonography in normal pregnancies.

Intravascular contrast media. Ionic versus nonionic: current status.

The development of LOCM is one of the most important medical discoveries made at the end of this century. In developing nonionic compounds, Almén showed that it was possible to decrease the osmolality by a factor of 2 and also thereby reduce the chemotoxicity by as much as a factor of 20. Serious adverse side effects after the intravascular administration of contrast material are caused by a combination of osmotoxic and chemotoxic properties of an individual contrast media molecule as well as the ionic composition of the agent when in solution. Worldwide clinical experience with the use of LOCM, ionic and nonionic, consistently has shown the new material to be safer and more comfortable in clinical practice. Some form of limited use of LOCM is now part of virtually every radiologist's daily practice, and the focus is turning to the low-risk-no-risk group. There are gray areas between risk categories, with some evidence even suggesting that the 20- to 40-year-old age group may be at risk to the same or even a greater degree than other commonly accepted risk groups such as the elderly. The future promises even better and safer but, in all likelihood, expensive, contrast agents for intravascular use. The ultimate decision on choice of contrast or the fate of LOCM rests with public policy makers, organized medicine, and the individual physician and patient. Based on penetration of the marketplace (nearly 50%) in terms of LOCM sales in 1990, there is a growing awareness within our specialty as well as the public sector of the improvements offered by LOCM. It is unlikely that a major conversion back to the universal use of HOCM will ever occur. As long as cost remains the major focus of the debate over the choice, however, physicians need to be informed advocates, familiar with the science, yet sensitive to the economic implications of the decisions they make to best serve the interests of their patients.

Ionic versus nonionic contrast use.

It has taken many years of research, development and intense scientific investigation to produce intravascular contrast media. Research on relations between chemical structure, animal toxicity, and water-solubility has produced a number of highly water-soluble, iodinated compounds for use in diagnostic radiology as intravascular contrast agents. The currently used intravascular agents may be classified into four groups according to their chemical structure: 1. Ionic monomers 2. Ionic monoacid dimers 3. Nonionic monomers 4. Nonionic dimers It is the objective of this publication to review the history and development of intravascular contrast media as well as their properties, general effects and clinical use. The four types of contrast media differ significantly in their chemical structure and physico-chemical properties, and these differences determine their osmotoxicity, chemotoxicity, and ion toxicity. We analyze the organ specific toxic effects of intravascular contrast media upon the central nervous system, the cardiovascular system, and the renal system. We also review the secondary effects, clinical manifestations, and the incidence of adverse events associated with different types of contrast. The choice of contrast media has become critical since the introduction of nonionic agents because their toxicological and pharmacological properties differ from those of the ionic agents. The application of basic concepts involved in the use of contrast media in excretory urography, computed tomography, angiography, and angiocardiography is discussed, and the advantages of the use of nonionic contrast agents are outlined. Economic and ethical issues are presented with emphasis upon strategies to reduce the risk associated with the injection of intravascular contrast and to curtail consumption according to rational principles of use.

Death following coronary angiography in a young woman with isolated left coronary ostial stenosis.

A 35-year-old woman with angina of five years duration underwent elective cardiac catheterization and coronary angiography which revealed left main stenosis. Immediately afterwards, the patient became distressed, hypotensive and bradycardic. She died despite emergency percutaneous transluminal coronary angioplasty and resuscitative efforts. Autopsy confirmed isolated left coronary ostial stenosis due to the combination of a congenital abnormality of the ostium and initial segment of left main coronary artery, together with a superimposed myointimal flap bridging the ostium. A unique association was an abnormal configuration of the ostia of the branches of the aortic arch.

Protective effects of corticosteroids in contrast material anaphylaxis.

A prospective, randomized study of the potential protective effects of corticosteroids administered as pretreatment against contrast material (CM) reactions is reported. Patients (n = 6,763) from multiple institutions received either a single dose of steroids (32 mg of oral methylprednisolone, approximately 2 hours before CM challenge), a double dose (32 mg approximately 12 hours and 2 hours before CM challenge), or placebo. All contrast injections were with ionic media and were given intravenously. The two-dose (but not the one-dose) corticosteroid regimen provided significant protection. The effect on reaction incidences of a number of historical variables is also tabulated.

Pretreatment with corticosteroids to alleviate reactions to intravenous contrast material.

The x-ray contrast mediums used over the past three decades have been salts of iodinated acids administered in highly hypertonic concentrations. We conducted a multiinstitutional randomized study of the protective effects of pretreatment with corticosteroids against reactions to intravenous contrast material. We gave 6763 patients two doses of oral corticosteroids (methylprednisolone, 32 mg) approximately 12 hours and 2 hours before challenge with contrast material, one dose of oral prednisolone approximately 2 hours before challenge, or placebo in the same dosages. The two-dose corticosteroid regimen, but not the one-dose regimen, significantly reduced the incidence of reactions of all types (P less than 0.05) except a category of reactions dominated by hives, for which the reduction approached significance (P = 0.055). In recent years, several relatively expensive monomeric nonionic iodinated compounds having approximately half the osmolality of the corresponding ionic compounds and a lower reaction rate have become available. With our two-dose corticosteroid regimen, the incidence of reactions necessitating therapy in patients receiving the ionic medium approximated that reported in an unblinded nonrandomized study of patients receiving a newer intravenous nonionic medium without corticosteroid pretreatment. We conclude that the much less expensive ionic medium, if administered with corticosteroid pretreatment, may serve as a reasonable alternative to intravenous nonionic medium, without loss of safety.

Intravenous digital subtraction angiography by peripheral injection.

We describe a technique for performing intravenous digital subtraction arteriography by peripheral injection and review our experience of 504 studies in 469 patients. The technique gave adequate opacification for anatomical definition of vessels in 93% of patients studied and was suitable for studies of the pulmonary arteries and left ventricle as well as the major systemic arteries. The chief causes of failure were impaired cardiac performance (2.4%) and poor patient cooperation (1.4%). Premature termination was caused by angina pectoris in 1.6% of our cases. These limitations apply also to central venous injection.