Cost-effectiveness of potentially life-saving implantable cardioverter defibrillators (ICD) is an important public health issue

The use of implanted defibrillators that keep the heart beating in proper electrical rhythm to prevent cardiac arrest appears to be cost-effective for those patients who receive a significant mortality reduction, according to researchers from Duke Clinical Research Institute (DCRI), Stanford University and the VA Palo Alto Health Care System, Calif. They analyzed eight clinical trials of the devices to arrive at their conclusion.

The cost-effectiveness of these potentially life-saving implantable cardioverter defibrillators (ICD) is an important public health issue, the researchers said, since the Centers for Medicare and Medicaid Services (CMS) estimates that as many as 500,000 of its patients could be eligible to receive these expensive devices.

The results of the team's analysis demonstrated that although expensive, in appropriate patients ICDs provide value. However, given the number of patients now eligible for ICD implantation, their analysis highlighted the need for further research into which patients are at higher risk for sudden cardiac death and therefore would benefit the most from this therapy, since the devices would be the most cost-effective for these patients, the researchers added.

ICDs are about the size of deck of cards and are surgically implanted under the skin of the chest, with wires attached to the heart. If the device senses a life-threatening irregularity of the heart rhythm, it delivers an appropriate electric impulse to bring the heart back into proper rhythm. ICDs have been proven effective in reducing sudden cardiac death in patients who had been resuscitated from a cardiac arrest, and the eight trials were designed to determine whether the devices could prevent sudden death in a healthier population of heart patients.

"Of the eight trials, two found no mortality benefits, so the use of an ICD was less effective and more expensive than for patients who did not receive an ICD," said Gillian D. Sanders, Ph.D., DCRI medical decision analyst and first author of a paper published Oct. 6, 2005, in the New England Journal of Medicine. "We found that the other six trials added significantly to life expectancy but at an increased cost, and that compared to control therapy, the cost of this additional gain in life expectancy was in the range of commonly accepted cost-effectiveness values."

"It is estimated that it would cost more than several billion dollars annually to implant ICDs in those patients for which they have been proven effective and are considered cost-effective," she continued. "If physicians extend the use of ICDs in lower-risk patients where the cost-effectiveness is even less favorable, the societal costs with increase even more."

Sanders led the study with colleagues from the Palo Alto (Calif.) VA Health Care System and Stanford University. The study was funded by the Department of Veterans Affairs, the Agency for Healthcare Research and Quality, and the Blue Cross Blue Shield Association Technology Evaluation Center.

For their analysis, the team used a model that accounts for a wide range of variables, including patient characteristics, whether the ICD generator needed replacement, clinical outcomes, medical costs, and quality of life parameters. In these analyses, researchers not only included the potential medication, hospitalization, procedure and other medical costs, but also took into account quality-of-life benefits patients receive for their added life expectancies.

Each "patient" in the model, whether they received an ICD or not, progresses year-by-year, with the outcome and cost estimated based on data drawn from the eight clinical trial results and studies published in the scientific literature. For their analysis, the researchers used 2005 Medicare costs of $27,975 for ICD implantation, and $18,390 for device replacement. A typical ICD generator lasts about five to six years.

From this model, the researchers could determine quality-adjusted life years (QALY) for each patient and their associated costs. According to Sanders, the generally accepted range for a therapy to be considered cost-effective is $50,000 to $100,000 per QALY, with interventions costing under $50,000/QALY generally being deemed good value for the money, and anything over $100,000/QALY is normally not seen as economically favorable.

"Our analysis demonstrated that as long as the benefit of the devices lasted for more than seven years, the use of an ICD costs less than $100,000/QALY compared to the control group," Sanders said. "The cost-effectiveness could be improved by either lowering the cost of the device or extending the ICD generator's life time."

Specifically, in the six trials where a definite mortality benefit was achieved, the use of an ICD added 1.01 to 2.99 QALYs at an additional $68,300 to $101,500 in cost over the patient's lifetime

"For those who benefited from ICD therapy, it was a large benefit that came at a cost comparable to other therapies we provide patients," she said, citing as examples the use of external defibrillators on commercial jets ($36,000/QALY) and the use of stents vs. angioplasty in patients with an acute heart attack ($24,000/QALY).

Because the patient characteristics of the eight trials were so different from each other, the researchers determined that they could not pool all the data for one combined cost effectiveness ratio, but instead reported their results specific to the individual trials.

"In January, CMS agreed to cover the costs associated with ICD implantation for patients with left ventricular dysfunction as long as the patient's clinical data is entered into a national ICD registry," she said. "We hope that as this data is collected and analyzed, we will be able to better distinguish the high-risk patients from the low-risk patients. This should help to make ICD use more cost-effective."

The two trials that found no benefit were CABG-PATCH and DINAMIT, while the other six trials were MADIT-I, MUSTT, MADIT-II, DEFINITE, COMPANION and SCD-HeFT. The trials involved ICDs produced by all the major device companies.

Joining Sanders, who also co-directs Duke's Center for the Prevention of Sudden Cardiac Death, in the analysis were Mark A. Hlatky, M.D., Stanford University and Douglas K. Owens, M.D., M.S. VA Palo Alto Health Care System and Stanford University.