Thursday, April 28, 2005

DCRI Researchers Analyze Cost-Effectiveness of ICDs in Heart Attack Patients
By Julie McKeel

In a new study estimating the cost-effectiveness of defibrillator implantation, DCRI researchers concluded that patients who receive the implantable cardioverter defibrillator (ICD) would be expected to live 1.8 years longer at a cost of $50,500 per extra year of life gained when compared with patients who received standard medical treatment.

The study focused on patients with a history of heart attacks or myocardial infarction (MI), and an ejection fraction of 0.3 or less. [The ejection fraction is the ratio of the volume of blood the heart empties during systole to the volume of blood in the heart at the end of diastole]. These patients met the Multicenter Automatic Defibrillator Implantation Trial II (MADIT II) eligibility criteria.

According to the investigators, while the number of patients eligible for an ICD would nearly double, the device is "economically attractive" based on conventional standards.

The results of the study are published in the most recent issue of the Annals of Internal Medicine.
According to the authors, sudden cardiac death is a major public health problem in the United States and claims the lives of approximately 300,000 people annually. Using ICDs reduces the risk for sudden cardiac death in certain patient populations, including heart attack survivors and patients with a history of heart attack and an ejection fraction of 0.4 or less. The MADIT II trial showed that heart attack patients with an ejection fraction of 0.3 or less have a 31% reduction in death rate when treated with an ICD compared with conventional medical treatments.

"The clinician needs to know the risks, benefits, and costs of the ICD among the subgroups of patients who may be candidates for this therapy," write the editorialists. They assert that the most reasonable approach to selecting patients for this procedure is to focus on patients who are at highest risk for sudden cardiac death after a heart attack and who do not have other significant existing conditions.

The editorialists note that there are still no precise methods for identifying patients who will benefit most from ICD therapy. As a result, many well-intentioned clinicians may choose to recommend ICD therapy in low-risk patients and thus the potential overuse of this treatment option would increase the costs. Physicians should use the cardiovascular profile of patients in MADIT II as their guide when making this treatment recommendation.

ICD therapy in heart attack patients resulted in longer life spans for the MADIT II population. Taking this data beyond the 20-month follow-up period for MADIT II, the researchers analyzed the cost-effectiveness of this treatment on patients in the Duke cardiovascular database with cardiovascular profiles similar to those patients in MADIT II.

The study sample included 1281 patients who were 21 years of age and older with a history of heart attack and an ejection fraction of less than 30% and who underwent cardiac catheterization. None of the patients in this sample received an ICD, having been treated before the MADIT II results were published.

The researchers calculated the number of years of life gained had the patients been treated with an ICD using the 31% benefit seen in MADIT II. They used this same percentage to calculate the total cost of care for ICD patients compared with the total cost of care for patients receiving standard medical treatment.

According to the study, the projected life span for the ICD group was 10.88 years compared with 8.26 years for the non-ICD group. After adjusting these future health outcomes to present-day values (using a discount rate of 3% per year), the ICD-treated group would be expected to live 1.8 years longer than patients who do not receive the ICD. The authors estimated the in-hospital and ICD costs, concluding that the cost of ICD therapy per life-year gained is $50,500.

"We found that the number of patients eligible for an ICD is not trivial, but in terms of doing the cost-effectiveness analysis, it is good to see that the benefit that was observed in the MADIT II trial can be extrapolated to other settings like ours," Al-Khatib told theheart.org. "The cost-effectiveness of implanting ICDs in these patients appears to be reasonable and comparable to other therapies that we currently use."

The cost-effectiveness of ICD therapy becomes even more favorable if the cost of the ICD is reduced to $10,000. In this scenario, the cost-effectiveness ratio is $45,200 per years of life gained. The researchers note that if the ICD battery lasted 10 years (as opposed to 5), the cost-effectiveness ratio is even better, decreasing to $42,500 per life-year gained.

In their paper, the authors indicate that if the study experiences were generalized, the results would imply that approximately 32,000 patients would meet MADIT II criteria for an ICD, doubling the number of ICDs implanted annually.

The editorialists write that this conservative estimation would increase the cost of implantation to $1 billion. They point out that other estimates have placed the cost of ICD therapy between $5 billion and $15 billion annually, depending on which eligibility criteria are used.

The editorialists note, and the Duke researchers agree, that the study is limited in that the costs of ICD therapy are projected from the Duke database. A more complete analysis based on the actual patient care costs in MADIT II will provide better information about cost-effectiveness. That analysis is expected soon.

Members of the DCRI research team for this study were Kevin J. Anstrom, PhD; Eric L. Eisenstein, DBA; Eric D. Peterson, MD, MPH; James G. Jollis, MD; Daniel B. Mark, MD, MPH; Yun Li, MS; Christopher M. O'Connor, MD; Linda K. Shaw, MS; and Robert M. Califf, MD.

Al-Khatib has consulted for Guidant Corp. She has also received grants and honoraria from Guidant and Medtronic Inc. The study was funded in part by Guidant.