Randomized comparison of the cost and effectiveness of iopamidol and diatrizoate as contrast agents for cardiac angiography

Advances in functional X-ray imaging techniques and contrast agents

X-rays have been used for non-invasive high-resolution imaging of thick biological specimens since their discovery in 1895. They are widely used for structural imaging of bone, metal implants, and cavities in soft tissue. Recently, a number of new contrast methodologies have emerged which are expanding X-ray's biomedical applications to functional as well as structural imaging. These techniques are promising to dramatically improve our ability to study in situ biochemistry and disease pathology. In this review, we discuss how X-ray absorption, X-ray fluorescence, and X-ray excited optical luminescence can be used for physiological, elemental, and molecular imaging of vasculature, tumors, pharmaceutical distribution, and the surface of implants. Imaging of endogenous elements, exogenous labels, and analytes detected with optical indicators will be discussed.

The renal patient with coronary artery disease

The patient with chronic kidney disease and coronary artery disease (CAD) presents special challenges. This report reviews the scope of the challenge, the hostile internal milieu predisposing to CAD and cardiac events, management issues, unresolved dilemmas, and the need for randomized trials to allow for evidence-based treatment.

Iodinated contrast sensitivity in ERCP

Iodine contrast media are detectable in the bloodstream after ERCP, and sensitivity reactions have been described. The risk is very small, and the phenomenon is therefore difficult to study. This review discusses the possible need for preventative strategies, and recommends that endoscopists consider the issue and define their own policies.

Safety and criteria for selective use of low-osmolality contrast for cardiac angiography

OBJECTIVES

Recommendations to restrict low-osmolality contrast to high-risk patients having cardiac angiography have been challenged because of safety and uncertainty about selection criteria. The authors document frequency and severity of adverse events with diagnostic cardiac angiography under the influence of guidelines for selective use of low-osmolality contrast in high-risk patients and refine high-risk criteria.

METHODS

Subjects of this prospective cohort study were 7,448 unselected patients having diagnostic cardiac angiography in St. John's, Newfoundland or Ottawa, Ontario. Measures included prespecified risk factors, procedure, contrast, and adverse events such as death within 24 hours, myocardial infarction, stroke, arrhythmias, hypotension, and anaphylactoid reactions.

RESULTS

Patients were similar at both sites. Fourteen point two percent received low-osmolality nonionic agents in St. John's. Thirty-four point one percent received low-osmolality (mostly ionic) media in Ottawa. Overall adverse event rates were similar at both sites: death, 0.07%; myocardial infarction or stroke, 0.03%; moderate events, 2%; and mild events, 16.8%. Event rates were low in those given high-osmolality media: death, 0.02%; myocardial infarction or stroke, 0.24%; moderate events, 1.6%; and mild events, 18%. The risk with cardiogenic shock and prior severe reaction to contrast could not be examined, but otherwise only current heart failure and markers of recent ischemia were associated with events after high-osmolality media.

CONCLUSIONS

Clinicians, using guidelines, can identify high-risk patients and should be able to safely limit use of low-osmolality media to them.

The role of perspective in defining economic measures for the evaluation of medical technology

Perspectives in an economic analysis of medical technology reflect who makes decisions about the use of or payment for medical resources. Commonly used perspectives include those of providers, insurers, the individual, and society. Perspective is a critical determinant of study design, affecting the time horizon, types of resources considered, and economic cost measures assigned to those resources. Individuals involved in technology assessment for either research or policy-making purposes should be aware of the complexities of defining costs from different perspectives.

The clinical-economic trial: promise, problems, and challenges

The clinical-economic trial is a study design that is appearing with greater frequency in medical and public health literature. Some experienced investigators view these trials with skepticism; to policy makers they represent a promising step in the control of rising health care costs. The success of clinical-economic trials in meeting the important goal of more rational and efficient use of health care resources will depend on the strengths and limitations of the research method. As part of a report to the Office of Technology Assessment of the U.S. Congress on new health care assessment techniques, we describe the reasons why economic data collection and analysis are being considered in clinical trials, identify and discuss various designs and methods for gathering economic trial data, and evaluate the strengths and limitations of different methods for providing sound data for decision making on appropriate use of health care interventions. Because of the potential significance and increasing visibility of such research, experts in research methods should give more attention to methodological research for clinical-economic trials. Future efforts should be directed at comparing different techniques for collecting data, examining the incremental value of precision in economic measurements and ensuring appropriate interpretation of data from clinical-economic trials.

An economic analysis of strategies for the use of contrast media for diagnostic cardiac catheterization

A decision tree model was used to estimate the incremental cost per quality-adjusted life year (QALY) of low- as opposed to high-osmolality contrast media for cardiac angiography. Analyses were done from the viewpoints of a third-party payer and society using data from a randomized trial and the literature. Assuming low-osmolality media reduce the risk of myocardial infarction and stroke, the incremental cost per QALY gained with these media is $17,264 in high-risk or $47,874 in low-risk patients for a third-party payer. From a societal viewpoint, the corresponding costs are $649 and $35,509. These estimates are sensitive to the cost and volume of the contrast medium employed and to the estimate of reduction in severe adverse events with low-osmolality media. The authors conclude that, in the context of restricted budgets, limiting the use of low-osmolality media to high-risk patients is justifiable, as the incremental cost per QALY in high-risk patients may be reasonable and it is not certain that low-osmolality media prevent severe or fatal events. A considerable reduction in the cost per QALY gained is possibly by minimizing the volume of contrast medium used.

Iomeprol and iopamidol in cardiac angiography: a randomised, double-blind, parallel-group comparison

During cardiac angiography, hemodynamic alterations and surface electrocardiographic changes are common, predictable and dose-related adverse reactions to radiocontrast media. High osmolality, inadequate sodium content and local transient hypocalcemia are thought to be the main mechanisms responsible for these untoward cardiovascular effects. The purpose of this double-blind, parallel-group trial was to compare the hemodynamic and electrocardiographic responses to cardiac and selective coronary artery injection of iomeprol 400 (400 mgI/ml) and iopamidol 370 (370 mgI/ml). One-hundred consenting adult inpatients were randomised to receive iomeprol 400 (41 males, nine females; mean age, 56.6 years) or iopamidol 370 (46 males, four females; mean age, 57.6 years). Both agents produced minor and transient hemodynamic and electrophysiological effects. Following left ventriculography, iopamidol 370 produced a significantly greater increase in LVEDP than iomeprol 400 (mean increases after first and second left ventriculogram: 2.5 and 4.6 mmHg with iomeprol 400, 3.3 and 9.9 mmHg with iopamidol 370, P = 0.027). The QT-interval was more affected by iopamidol 370 than by iomeprol 400. However, post-contrast prolongation of the QT-interval was not significant with either agent, nor were there any significant T-wave, ST-segment or RR-interval changes associated with the injection of the test compounds. No serious adverse events occurred throughout the study. Mild pain was complained by only one patient, while most patients reported mild to moderate sensation of heat. Image quality of the vast majority of the procedures was rated as good or excellent in both patient groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevention of anaphylactoid reactions in high-risk patients receiving radiographic contrast media

OBJECTIVE

To review various pretreatment regimens for the prophylaxis of anaphylactoid reactions to radiographic contrast media (RCM) in high-risk patients. The proposed etiologies and risk factors for such reactions are also reviewed.

DATA SOURCES

A MEDLINE search of the English-language literature was used to identify pertinent human studies and reviews.

STUDY SELECTION

All studies comparing pretreatment regimens for anaphylactoid reactions to RCM were reviewed as well as studies comparing the incidence of anaphylactoid reactions between lower and higher osmolar RCM.

DATA SYNTHESIS

The two types of reactions to RCM are dose-independent, unpredictable anaphylactoid (pseudoallergic or idiosyncratic) reactions and the dose-dependent, predictable physicochemical (intrinsic, nonidiosyncratic) reactions. Prophylaxis of the former type is targeted at stemming the effects of certain chemical mediators, primarily histamine. The use of lower osmolar RCM is associated with a lower incidence of anaphylactoid reactions compared with higher osmolar RCM, but is significantly more expensive. Risk factors for such reactions are a history of previous anaphylactoid reaction to RCM, asthma, and reaction to skin allergens or penicillin. Discontinuation of any beta-blockers before the procedure is suggested. Pretesting patients with a small amount of RCM has little predictive value for an anaphylactoid reaction. Various pretreatment prophylactic regimens have been studied. Almost all included a corticosteroid to target the inflammatory response and a histamine1 (H1)-antagonist to blunt the effects of histamine. In some clinical trials, ephedrine was added for bronchodilation and cimetidine for its antagonism at the histamine2-receptor. The few controlled clinical trials that have been performed show the combination of prednisone and diphenhydramine to be most beneficial in preventing anaphylactoid reactions to RCM. The addition of ephedrine or cimetidine to a pretreatment regimen remains controversial.

CONCLUSIONS

More controlled clinical studies comparing various pretreatment regimens for high-risk patients need to be performed, especially in patients receiving lower osmolar RCM. Recommendations for high-risk patients who must receive RCM include use of a lower osmolar agent, pretreatment with a corticosteroid and an H1-antagonist, discontinuation of beta-blockers if the patient is taking any, and bedside availability of appropriate medications and equipment to treat anaphylaxis.

Comparison of a low osmolarity nonionic radiographic contrast agent with a standard medium on renal function in cyanotic and normal dogs

Renal dysfunction may follow administration of iodinated radiographic contrast agents. This complication may be less common when low osmolarity nonionic agents are used. Although potential benefits from the use of low osmolarity nonionic contrast may be minimal in individuals with normal physiology, a greater benefit has been postulated in the presence of chronic cyanosis. To test this hypothesis, six adult mongrel dogs underwent anastomosis of the inferior vena cava to the left atrium. This produced chronic cyanosis with a mean pO2 of 48 +/- 4 mm Hg and polycythemia with a mean hematocrit of 56 +/- 2 gm%. Three to 5 months after preparation, these cyanotic dogs and five control dogs each received diatrizoate (a high osmolarity ionic agent) or ioversol (a low osmolarity nonionic agent), 465 mg iodine/kg body weight, by intravenous bolus injection. One month later, each animal received the other agent. The order of administration was randomized. Renal function studies, including serum creatinine and creatinine clearance, were performed precontrast, after 60 min, and 24 hr postcontrast. Neither agent adversely affected renal function in either the cyanotic or the normal group. We conclude that at the doses that are commonly used in clinical practice, high osmolarity ionic contrast agents do not create a greater risk of renal injury than do low osmolarity nonionic agents in this model of cyanosis.

A comparison of low- with high-osmolality contrast agents in cardiac angiography. Identification of criteria for selective use

BACKGROUND

Controversy exists as to whether low-osmolality radiographic contrast agents, which have less detrimental pharmacological effects but are considerably more expensive than high-osmolality agents, should be used universally or only for selected high-risk patients.

METHODS AND RESULTS

A randomized, double-blind study was used to compare the frequency and severity of adverse events in 2245 consecutive patients undergoing diagnostic cardiac angiography. Two thousand one hundred sixty-six patients were successfully randomized to either iohexol, a low-osmolality contrast agent, or diatrizoate (as Hypaque 76), a high-osmolality agent. The end point event included clinically important adverse events (which jeopardized the patient or required aggressive treatment), contrast agent-related procedure abbreviations, and conversion to open-label contrast agent. Clinically important end point events were associated with increased age, New York Heart Association functional class, left ventricular end-diastolic pressure, arteriovenous oxygen difference, severity of coronary artery disease, and history of a previous reaction to contrast agent. End point events were less frequent in patients receiving iohexol (2.6% versus 4.6%; adjusted odds ratio, 1.59; 95% confidence interval, 0.97-2.60; P = .07). The difference in event frequency between iohexol and diatrizoate was confined to the highest-risk quartile of the patient population. An algorithm was developed to classify patients as being at high or low risk for an event based on patient age, New York Heart Association class, history of a prior contrast reaction, and left ventricular end-diastolic pressure. Application of this algorithm for selective use of low-osmolality agents only for high-risk patients to a theoretical population of 1000 patients reduced contrast agent costs 66% without increasing the frequency of contrast agent-related adverse events.

CONCLUSIONS

The advantages of low-osmolality contrast agents are clinically important in patients with severe heart disease but are not in less ill patients. Universal use of low-osmolality agents for cardiac angiography in an unselected population is not necessary. Appropriately guided selective use of low-osmolality contrast agents is feasible and has the potential to reduce cost substantially without compromising safety or effectiveness.

Net costs from three perspectives of using low versus high osmolality contrast medium in diagnostic angiocardiography

OBJECTIVES

We conducted an economic analysis to assess the extent to which a reduction in adverse drug reactions induced by low osmolality compared with high osmolality contrast media during diagnostic angiocardiography would result in savings to hospitals, society and third-party payers that would offset the substantially higher price of low osmolality contrast medium.

BACKGROUND

Substitution of low osmolality for high osmolality contrast media in the approximately 1 million diagnostic angiocardiographic procedures performed each year in the United States could substantially increase health care costs. Cost-effectiveness estimates should include savings that might occur through reduced costs of managing adverse drug reactions.

METHODS

In a randomized clinical trial of 505 persons under-going diagnostic angiography with either high osmolality or low osmolality contrast medium, we measured and compared 1) material costs of contrast media, and 2) costs from three perspectives of incremental resources used to manage contrast-related adverse drug reactions. We also performed sensitivity analyses to examine the effect of different assumptions with regard to relative risk, absolute risk and costs of adverse drug reactions on estimates of net cost of use of high osmolality and low osmolality contrast media.

RESULTS

One-hundred thirty-seven (54.2%) of 253 patients receiving high osmolality contrast medium and 44 (17.5%) of 252 patients receiving low osmolality contrast medium experienced adverse drug reactions. The average cost (from society's perspective) of resources used to manage adverse drug reactions per patient undergoing angiography was significantly (p = 0.0001) greater for high osmolality (mean $249) versus low osmolality (mean $92) contrast medium. Differential costs (from the hospital's perspective) were $67 greater for high osmolality contrast medium. Charges and professional fees (from the payer's perspective) were $182 greater for high osmolality (mean $312) than for low osmolality (mean $130) contrast medium (p = 0.42, NS). The higher differential and average costs of managing adverse drug reactions with high osmolality contrast medium offset 33% and 75%, respectively, of the $207 difference in mean material costs, but these estimates are sensitive to infrequent high cost cases.

CONCLUSIONS

Although low osmolality contrast medium is not cost-saving in diagnostic angiocardiography, its higher price is partially offset by lower management costs of adverse drug reactions. The cost offset for the hospital is lower than that for society and may not be realized by third-party payers. These methods and results may be useful in establishing clinical and payment guidelines for use of alternative contrast media in diagnostic angiocardiography.

Use of nonionic or low osmolar contrast agents in cardiovascular procedures. American College of Cardiology Cardiovascular Imaging Committee

Low osmolar contrast agents produce less adverse electrophysiologic and hemodynamic alterations during cardiac catheterization. The nonionic agents probably reduce the risk of provoking myocardial ischemia during coronary arteriography or ventriculography. Patients also report less subjective sensation of discomfort during administration of low osmolar agents for cardiovascular procedures. However, nonionic agents have not been proved to reduce the incidence of several serious complications of cardiac catheterization, including acute renal failure and anaphylactoid reaction. Although evidence is inconclusive, there may be an increased risk of thromboembolic complications during cardiac catheterization when certain low osmolar nonionic agents are administered. Nonionic contrast agents have not been definitely proved to reduce the risk of death after cardiac catheterization.

A comparison of nonionic, low-osmolality radiocontrast agents with ionic, high-osmolality agents during cardiac catheterization

BACKGROUND

Nonionic, low-osmolality radiocontrast agents are used frequently because they are believed to be safer than ionic, high-osmolality agents, but they are also more expensive. We conducted a randomized trial to compare the incidence of adverse events after the administration of ionic, high-osmolality and of non-ionic, low-osmolality radiocontrast agents during cardiac angiography.

METHODS

We compared the need to treat patients for adverse reactions and the frequency and severity of specific hemodynamic, systemic, and symptomatic side effects in two groups of patients randomly assigned to receive either ionic, high-osmolality or nonionic, low-osmolality radiocontrast material, and also in 366 patients who could not be randomized.

RESULTS

Treatment for adverse events was required in 213 of 737 patients who received high-osmolality contrast agents (29 percent) but in only 69 of 753 patients who received nonionic agents (9 percent) (95 percent confidence interval for the percent difference, 15.9 to 23.6 percent). Hemodynamic deterioration and symptoms also occurred more often in the high-osmolality group, as did severe or prolonged reactions (2.9 percent, as compared with 0.8 percent in the nonionic group; P = 0.035). The severe reactions were largely confined to patients with severe cardiac disease. Multivariate analysis showed that the presence of severe coronary disease and unstable angina were predictors of clinically important adverse reactions. If all the patients in our randomized trial had been given nonionic contrast material, the incremental cost per procedure would have been $89.

CONCLUSIONS

Nonionic, low-osmolality contrast material is better tolerated during cardiac angiography than ionic, high-osmolality contrast material. Since cost constraints may prevent the universal use of nonionic contrast material, its selective use in patients with severe cardiac disease could be considered.

Safety and cost effectiveness of high-osmolality as compared with low-osmolality contrast material in patients undergoing cardiac angiography

BACKGROUND AND METHODS

Low-osmolality contrast agents produce fewer hemodynamic and electrophysiologic alterations during cardiac angiography, but they are 20 times more expensive than high-osmolality contrast agents. In a randomized, double-blind trial comparing a nonionic low-osmolality contrast agent (Omnipaque 350) with a high-osmolality agent that does not avidly bind calcium (Hypaque 76) in 505 patients undergoing cardiac angiography, we determined the incidence of minor, mild, moderate, and severe adverse reactions, identified risk factors for such reactions, and evaluated the cost effectiveness of various strategies for the use of contrast material.

RESULTS

The 253 patients who received a high-osmolality contrast agent were three times more likely to have a moderate adverse reaction (95 percent confidence interval for the relative risk, 1.6 to 5.5) but no more likely to have a severe reaction (95 percent confidence interval, 0.2 to 2.3) than the 252 patients who received a low-osmolality agent. All 10 severe reactions occurred in patients who were older than 60 years or had unstable angina. Patients with these characteristics were also 3.5 times more likely (95 percent confidence interval, 1.8 to 6.8) to have a moderate reaction (44 of 310 patients, or 14 percent) than those without either characteristic (8 of 195 patients, or 4 percent). We estimated that the incremental cost of each moderate reaction avoided would be $1,698 with a strategy that involved giving a low-osmolality contrast agent only to patients who were over 60 years of age or had unstable angina, instead of giving a high-osmolality agent to all patients. The incremental cost per moderate reaction avoided by giving a low-osmolality contrast agent to all patients rather than only to those over 60 or with unstable angina would be $5,842.

CONCLUSIONS

The use of contrast agents with low rather than high osmolality during cardiac angiography reduces the risk of moderate, but not of severe, adverse reactions to the agent used. A strategy of reserving low-osmolality contrast agents for use in patients at high risk for adverse reactions would be more cost effective than one requiring their use in all patients.

Nephrotoxicity of contrast media following cardiac angiography: pathogenesis, clinical course, and preventive measures, including the role of low-osmolality contrast media

OBJECTIVE

To review the incidence, definition, clinical course, risk factors, pathogenesis and prevention of contrast-associated nephropathy (CAN) following cardiac angiography with emphasis on differences between high-osmolality contrast media (HOCM) and low-osmolality contrast media (LOCM).

DATA SOURCES

Investigations in animal models and in patients following cardiac angiography.

DATA EXTRACTION

Animal models of the pathogenesis of CAN are presented. Human studies describing the incidence, clinical course, risk factors, and prevention of CAN are reviewed. Comparative clinical trials of HOCM (diatrizoate, metrizoate) and LOCM (iohexol, iopamidol, ioxaglate) nephrotoxicity following cardiac angiography are critically evaluated.

DATA SYNTHESIS

All clinical studies comparing CAN of HOCM versus LOCM following cardiac angiography have some methodologic limitations (e.g., small sample size, lack of control for other factors) that may affect renal function, lack of stratification for other reported risk factors, and variable or short follow-up periods.

CONCLUSIONS

Whether the incidence of CAN following cardiac angiography is reduced with LOCM remains controversial. The incidence of CAN in patients with normal renal function does not appear to differ in patients treated with LOCM versus HOCM because few patients in each group develop renal failure. Additional controlled clinical trials comparing CAN of LOCM and HOCM in patients with renal dysfunction are needed. Because of greater product cost and scarcity of documented benefit compared with HOCM, selection of LOCM based on the presence of renal dysfunction cannot be recommended at this time.

Choice of contrast agents for cardiac angiography: review and recommendations based on clinically important distinctions

Low osmolal contrast agents (LOCA) are measurably superior to high osmolal contrast agents (HOCA) in a number of properties. However, LOCA are substantially more expensive than HOCA, and universal use of LOCA for cardiac angiography would strain the health care budget. Therefore, the choice to use LOCA in place of HOCA should be based on clinically important differences. Review of available published data suggests that HOCA can be used safely and effectively for cardiac angiography in patients with mild or moderately severe heart disease. When HOCA are used, those that do not bind calcium should be chosen as they cause fewer clinically important adverse reactions than those that do bind calcium. Use of LOCA may offer added safety in high risk patients, although to date, this conclusion has not been proved with clinical experience. Nonionic LOCA may be safer to use than ionic LOCA.