NON-IONIC CONTRAST AGENTS: SELECTIVE USE IN HIGH RISK PATIENTS

NON-IONIC CONTRAST AGENTS: SELECTIVE USE IN HIGH RISK PATIENTS is more cost effective for that population than a universal use of the newer and more expensive non-ionic low-osmolality contrast imaging agents in patients undergoing cardiac angiography, a Johns Hopkins University study published in the Feb. 13 New England Journal of Medicine finds. "A strategy of reserving [non-ionic] 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," Earl Steinberg, MD, et al. concluded. The study shows that using non-ionic, low-osmolality contrast materials for a limited population, such as patients over the age of 60 or those with unstable angina, would be significantly beneficial while controlling the costs associated with the use of the low-osmolality agents, which are "20 times more expensive than [ionic] high-osmolality contrast agents," the researchers reported. The increased cost of using low-osmolality agents, as opposed to the older ionic agents, outside this high risk group is not as cost effective, the authors suggest. The researchers compared Sterling Winthrop's non-ionic, low- osmolality agent Omnipaque 350 with the company's high-osmolality agent Hypaque 76 in a randomized, double-blind trial of 505 patients undergoing cardiac angiography. Overall, 54% of patients receiving the high-osmolality contrast agent had adverse reactions compared to 17% of patients who were given the low-osmolality agent. While there was a significant difference between high and low- osmolality agents with regard to moderate adverse reactions, 15% v. 5%, there was no significant difference in severe adverse events, which were 2% for both agents. The authors also note that moderate reactions such as bradycardia, hypotension and angina, were easily treated. In addition, 85% of the moderate adverse events occurred in patients who had unstable angina or were over 60. Steinberg et. al. estimate that if low-osmolality contrast agents were given only to patients in the high-risk group and high-osmolality agents to all others, moderate adverse reactions would be reduced by 114 per year at an increased cost of $1,116 for each moderate reaction avoided. Giving low osmolality agents to all patients would only reduce the number of moderate adverse reactions by an additional 16, but increase the cost of each moderate reaction avoided by $5,842, the researchers estimate. The cost of 200 ml of high-osmolality contrast agent is $8, while the same amount of low-osmolality agent costs $170. A second study published in the Feb. 13 NEJM concurs with Steinberg et al. with respect to using the higher cost non-ionic contrast agents in selected patient populations. The study, conducted by Brendan Barrett, et al., Memorial University, St. John's, New-foundland, discovered that adverse events requiring treatment occurred in 29% of patients receiving high-osmolality contrast compared to 9% of patients being given low-osmolality agents during cardiac catheterization. In the study, 737 patients received high-osmolality agents -- either Bristol-Myers Squibb's Renografin 76 or MD-76 -- and 753 patients were administered the non-ionic, low-osmolality agents iohexol (Omnipaque) or iopamidol. Severe or prolonged reactions occurred in 2.9% of patients receiving the ionic agents compared to .8% receiving non-ionic agents. The severe reactions occurred mostly in patients with severe cardiac disease or angina. The researchers observed that if all patients in the study had received low-osmolality agents, the cost per procedure would have gone up by $89. "The results of this trial underscore the problem confronting those who determine health policy when a new therapy is found to be superior to a conventional one but at a higher cost," the authors note. "It may be possible to use it selectively in the patients at highest risk for serious adverse effects -- a more economical policy," they added. In an accompanying editorial, John Hirschfeld, MD, University of Pennsylvania School of Medicine, supported the idea that non- ionic contrast agents "should be reserved for higher-risk patients who will derive a commensurate benefit." The "existence of a large group of patients at low risk who derived no cinical benefit from low-osmolality low risk who derive no clinical benefit from low- osmolality agents and the fact that almost all adverse reactions are easily managed argue for selective rather than universal use of the expensive agent," Hirschfeld stated. However, he noted that "the boundaries that separate patients who should receive low- osmolality agents from those who should not are not clearly demarcated."