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(BETHESDA, MD) - A cost-effectiveness analysis involving the potential implications of using a screening test before deciding to implant cardioverter-defibrillators (ICDs) in Medicare patients at risk of developing life-threatening heart arrhythmias indicates that it is much less cost-effective to give implants to lower-risk patients, according to a study in the July 4, 2006, issue of the Journal of the American College of Cardiology.
“What we wanted to examine was whether or not it would be more cost-effective to use this test, microvolt T-wave alternans, to screen the “MADIT-II” eligible population and to make decisions on defibrillator implantation based on the screening process. We modeled those patients who tested non-negative with this test to receive a defibrillator, whereas patients who tested negative would receive best medical therapy only, because of their lower risk,” said Paul S. Chan, M.D., M.Sc., from the VA Center for Practice Management and Outcomes Research and the University of Michigan in Ann Arbor, Michigan.
MADIT-II was a major clinical trial that studied the benefits of implanting defibrillators in patients who had heart failure following a heart attack. The model used in this study included patients similar to those who fit the criteria for the MADIT-II trial.
Microvolt T-wave alternans is a method of analyzing electrocardiograms for subtle alterations in a part of the heart beat known as the “T-wave.” Previous studies have indicated that patients who test positive or have indeterminate findings (a non-negative result) have two to five times as high a risk of death or a dangerous heart arrhythmia as do patients who have a negative result on this test.
The researchers used a mathematical model to simulate different treatment decisions in a population of 65-year-old Medicare patients who are considered eligible for defibrillator implants for primary prevention against sudden cardiac death. Using data from established clinical trials and the medical literature, their model compared the lifetime costs and benefits of a medical therapy strategy to prevent death, implanting defibrillators in all currently eligible patients, or implanting defibrillators in only those patients considered to be at higher risk according to the microvolt T-wave alternans test and then using drugs to treat the rest.
The researchers looked at the number of “quality-adjusted” years of life that the different treatment options would be expected to provide to patients. The “quality adjustment” takes into account the fact that even with the best medical treatment, the patients are not in perfect health and are still dealing with a chronic heart problem. However, the researchers said that removing this “quality adjustment” did not significantly alter their results.
Overall, the researchers calculated that, on average, patients in this group who received a defibrillator would live almost one-and-a-half “quality-adjusted” years longer than patients on drug therapy (7.3 years vs. 5.9 years) and the additional cost per “quality-adjusted” life-year would be about $56,000. By comparison, kidney dialysis treatment costs about $50,000 per “quality-adjusted” year of life.
However, when the researchers factored in the screening test, they found that almost all the benefits went to high-risk patients, and that the one-third of patients testing negative and who received defibrillators would live only slightly longer than if they were treated with medical therapy.
“The cost-effectiveness ratio for implanting defibrillators in the lower risk negative group was closer to $90,000 per quality-adjusted life-year, which would not be considered cost effective by commonly accepted thresholds. In contrast, putting a defibrillator in an eligible population who test non-negative would be less than $50,000 per quality-adjusted life-year, which would be considered modestly cost-effective,” Dr. Chan said.
Dr. Chan emphasized that they are not saying certain patients should not receive implantable defibrillators, but just that society should be aware of the relative costs and benefits of different options.
“We are not saying that we shouldn’t be putting implantable defibrillators in those patients who test negative. What we are saying is that this test helps to identify a higher risk subgroup for which defibrillator therapy is cost-effective and a lower risk subgroup for which defibrillator therapy exceeds commonly acceptable thresholds for cost-effectiveness. To date, there have been no direct studies examining whether there is any benefit to be derived from implanting defibrillators among those testing microvolt T-wave alternans negative. Until such studies are done, the benefit of implanting defibrillators in this lower-risk group will remain unknown. However, with this study, we were able to show that defibrillators would likely not be considered cost-effective even if there is some benefit with defibrillators in this lower-risk negative group,” Dr. Chan said.
Dr. Chan said that nationwide there are about 32,000 new patients a year who fit the “MADIT-II” study definition they used, but that Medicare uses a broader definition that could mean more than 100,000 patients would be eligible for a defibrillator implant for primary prevention each year.
He emphasized that this study is a mathematical model based on recent studies and they did not monitor actual patients. However, the researchers ran 10,000 different computer simulations using different assumptions about key variables. Dr. Chan said none of those simulations indicated that the cost-effectiveness of giving implants to lower-risk patients would be below $50,000 per “quality-adjusted” life-year, while almost a third of the simulations produced cost-effectiveness estimates higher than $100,000 per “quality-adjusted” life-year.
“Therefore, this suggests that putting a defibrillator in those who are in the lower-risk, T-wave alternans negative population is going to cost a lot more per quality-adjusted life-year. You don’t get as much bang for the buck,” Dr. Chan said.
Matthew R. Reynolds, M.D. from Beth Israel Deaconess Medical Center in Boston, Massachusetts, who was not connected with this study, said that like any mathematical model, it is speculative, but that it is a well-done model that is consistent with the results of other studies and for the first time places the clinical utility of T-wave alternans testing in the context of cost-effectiveness.
Dr. Reynolds noted that Medicare recently announced that it will pay for T-wave alternans testing on a national basis for patients considering ICD implantation.
“It’s not mandatory; and I don’t think these data suggest that it ought to be mandatory,” Dr. Reynolds said. “However, most countries have more constrained health care budgets than the U.S., and cost-effectiveness data play a larger role in health care policy in such places.”
He said testing is most useful when patients and physicians are on the fence about which course of action is best.
“I think there are clear-cut cases where patients and their doctors agree that an ICD should be put in, and I think there are cases that are less clear-cut... where being able to obtain this kind of information may improve decision-making,” he said. “I had a patient come to me and request this test because he was very reluctant to have an ICD put in. In that particular case, I think the results of the test will be helpful.”
Dr. Reynolds said that it is up to policymakers to decide the larger issues of cost-effectiveness of different medical treatments.
Leslee J. Shaw, Ph.D., from Cedars-Sinai Medical Center in Los Angeles, California, who also was not connected with this study, remarked that the results indicate this screening test could provide tremendous savings.
“Our cost-overburdened health care system is often the result of unrestrained use of expensive technology,” Dr. Shaw said. “The report by Chan et al. provides us with alternative options to focus the use of expensive procedures, such as ICDs. The strategy by Chan and colleagues is part of a growing number of evaluations that devise techniques to utilize effective gatekeepers to expensive technology.”
The following cost estimates were included in this analysis:
- Heart failure and heart disease treatment for all patients: $10,600 per year
- Initial costs of ICD and implantation: $35,000
- ICD generator replacements every six years: $18,000 per replacement
Other estimated costs for treatment complications and serious medical events were also included.
Contact: Paul S. Chan, M.D., M.Sc., VA Ann Arbor Center for Practice Management and Outcomes Research, Cardiology (111-A), 2215 Fuller Road, Ann Arbor, Michigan 48105. Telephone: 734-936-6266, ext.11159 Fax: 734-761-2939 E-mail: firstname.lastname@example.org
Dr. Chan is supported by a National Institutes of Health Cardiovascular Multidisciplinary Research Training Grant and by the Ruth L. Kirchstein Research Service Award. Neither sponsor had any involvement in the design, collection, management, or analysis of the study or in manuscript preparation.
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