ICDs deliver electrical shocks to the heart to eliminate abnormal rhythms such as ventricular fibrillation or ventricular tachycardia. In the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial, the device was shown to be superior to therapy with antiarrhythmic medications for reducing all causes of death in survivors of ventricular fibrillation (irregular, chaotic heart rhythm that begins in the heart’s lower chambers). It was also a better choice for people with ventricular tachycardia (an often serious rapid rhythm originating in the lower chambers) and ejection fractions of 40 percent or less. Ejection fraction is a measure of the heart’s pumping ability.
AVID is the first study to prospectively determine the cost-effectiveness of ICDs for secondary prevention in the United States, according to lead author Greg Larsen, M.D, a staff cardiologist at the Portland VA Medical Center and associate professor of medicine at the Oregon Health and Sciences University, Portland, Oregon. The study looked only at treating patients who had had life-threatening arrhythmias and were at risk for another life-threatening event. Researchers compared life gained and costs due to ICD treatment with that of antiarrhythmic drug therapy.
To find out which treatment was more cost-effective, researchers compiled data on charges for initial and repeat hospitalizations, emergency room and day surgery stays, and the costs of antiarrhythmic drugs from 1,008 patients. These included 505 patients with an ICD. Detailed records of all other medical encounters and expenses, including outpatient services and prescription costs, were collected on a subgroup of 237 patients, who were a balanced representation of the larger trial, geographically and medically.
“We called these the ‘shoebox patients,’ because we told them we wanted all their bills – just bring them in a shoebox,” says Larsen. The researchers converted the charges to 1997 costs. Three-year survival data from AVID were used to calculate the base cost effectiveness (C/E ratio). Six-year, 20-year and lifetime C/E ratios were also estimated.
The researchers determined that the largest expense for these patients is inpatient care, which makes up between 73 percent of total costs for drug therapy patients and 84 percent for ICD patients. At three years, the cost for the drug treatment group was $71,421. For the defibrillator group it was $85,522. The ICD provided a 0.21-year average survival benefit, putting the cost-effectiveness ratio at $66,677 per year of life saved.
“The defibrillator patients lived longer, but they paid extra to get that extra life. The ratio of the additional amount paid for the additional survival benefit is the cost-effectiveness number,” Larsen says.
According to Larsen, the conventional wisdom about cost-effectiveness ratios is that something is a “bargain” below about $50,000 per year of life saved, “so the defibrillator is just on the margin of that bargain. It’s on the high side but not out of reason.”
The researchers also found that six- and 20-year C/E ratios remained stable between $68,000 and $80,000 per year of life saved.
This is only the beginning when it comes to cost-effectiveness studies on the devices, Larsen says. “The cost effectiveness issue is going to be a very big part of the defibrillator story during the next year or two as more and more people look to ICDs for treatment.”
For example, there may be changes in some of the big expenses from the ICD group, such as how often the ICD battery may need to be replaced, he says. At three years, 18 percent of the people in this study had to have new batteries. It’s also possible that in-patient costs could go down – this study showed shorter hospital stays over time.
“Clearly the cost of these devices is high but the medical care costs are high as well. As the authors point out, ICDs are moderately cost effective in these patients,” says David Faxon, M.D., president of the American Heart Association. “We need to continue to study cost effectiveness issues and determine the best practice policies for patients.”
Co-authors are Alfred Hallstrom, Ph.D.; John McAnulty, M.D.; Sergio Pinski, M.D.; Anna Olarte, M.Sc.; Sean Sullivan, Ph.D.; Michael Brodsky, M.D.; Judy Powell, B.S.N.; Christy Marchant, R.N., M.B.A.; Cheryl Jennings; Toshio Aklyama, M.D., Ph.D.; and the AVID investigators.
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