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Synopsis: Implantable cardioverter defibrillator therapy is not cost effective by currently accepted standards for therapy of cardiac arrest survivors and patients with sustained ventricular tachycardia.
Source: O’Brien BJ, et al. Circulation. 2001;103:1416-1421.
O’Brien and colleagues report a preplanned economic substudy of the Canadian Implantable Defibrillator Study (CIDS). This trial was a perspective comparison of implantable cardioverter defibrillator (ICD) use vs. amiodarone treatment in patients who survived an episode of cardiac arrest or sustained ventricular tachycardia or who had unexplained syncope with ventricular tachycardia induced at a later electrophysiologic study. In CIDS, 659 patients were randomized to receive initial therapy with either an ICD (n = 328) or amiodarone (n = 331). During the trial, the annual risk of death from any cause was 8.3% in the ICD group vs. 10.2% with amiodarone. This was a 19% reduction in mortality, which was not significantly different from the reduction with the ICD observed in 2 other secondary prevention trials of ICD therapy. The economic substudy reported here was performed on the first 430 patients recruited into CIDS.
Patient-specific data were collected on length of hospital stays, ICD implants and generator replacements, other cardiac surgical or major diagnostic procedures, outpatient physician visits, and diagnostic procedures. Resource use was collected from the viewpoint of a provincial government health care provider at preselected intervals. Costs for ICD systems were based on current Canadian market prices, and other expenses were based on medical care costs in Southwest Ontario. In the initial analysis, effectiveness was defined as the gain in years of life associated with ICD therapy during the trial. In an additional analysis, the cost-effectiveness of ICD usage was extrapolated over a longer period and modeled out to 12 years with survival assumptions of either the benefit continuing, remaining stable, or declining over time. Costs and survival benefits were discounted at a rate of 3% per year.
In CIDS, the mortality rate was 10.2% per year in the amiodarone group and 8.3% per year in the ICD group for a relative risk reduction in all-cause mortality of 19.7%. Life expectancy over the 6.33 years of follow-up was 4.65 years with amiodarone and 4.91 years with ICD, a discounted difference of 0.23 years. The mean length of the initial hospitalization was relatively long in the ICD group (4.7 days of intensive care plus an additional 12.0 days on the ward). This was longer than the initial hospitalization in the amiodarone group (2.0 days of intensive care plus 8.3 days on the ward). After the initial hospital stay, there were 708 hospital readmissions among 212 ICD patients vs. 584 readmissions among the 218 amiodarone patients. After the initial hospital stay, there was a total of 85 ICD generator implants or replacements in the ICD group as well as 40 ICD implants as patients in the amiodarone group crossed over to ICD therapy. These implants were analyzed using an estimated cost for implant in Canadian dollars (Can$) of Can $39,093 of which Can $22,000 was the cost of the device. Generator replacement costs were estimated as Can $29,012 per occurrence.
The initial hospital cost was greater in patients assigned to an ICD (Can $48,874) than in those given amiodarone (Can $7,927). Including follow-up costs over the 6-year period, the cumulative expected cost per patient was Can $87,715 for ICD patients and Can $38,600 for amiodarone patients. This translates to an incremental cost effectiveness of Can $213,543 per life-year gained with a 95% confidence interval lower boundary of Can $88,187. A number of factors were analyzed in a sensitivity analysis. Among patients with ejection fractions lower than 35%, the incremental cost for life-year gained was Can $108,484 whereas in those with ejection fractions ³ 35%, amiodarone therapy was dominant. ICD implant therapy still remained fairly expensive in models if the ICD cost was reduced to $16,000 and if the total hospital length of stay was reduced to 5 (or even 1) days. If benefit continued and the survival curves continued to diverge, the cost decreased substantially to Can $99,420 per life-year gained. Even with extrapolation to 12 years follow-up, ICD remained fairly expensive per life-year gained if the survival curves remained parallel (Can $118,688) or converged (Can $149,710).
Finally, O’Brien et al compared their cost effectiveness data to those reported by Multicenter Automatic Defibrillator Implantation Trial (MADIT)1 and the Antiarrhythmics vs. Implantable Defibrillators (AVID) study investigators.2 In MADIT, a higher event rate and a greater reduction in mortality resulted in a favorable cost per life-year gained of Can $39,764. In AVID, the event rate and risk reduction were closer to those in CIDS and the cost per life-year gained was Can $169,240.
O’Brien et al conclude that ICD therapy is not cost effective by currently accepted standards for therapy of cardiac arrest survivors and patients with sustained ventricular tachycardia.
Comment by John P. DiMarco, MD, PhD
The ICD has been shown to improve survival when compared to medical therapy in the primary and secondary prevention of sudden cardiac death. However, an ICD is an expensive medical device and ICD therapy terminates arrhythmia episodes but does not eliminate, and may increase, future hospitalizations and medical costs. ICD cost-effectiveness has been analyzed in several trials and, as summarized in this paper, cost-effectiveness is strongly related to the frequency of events in the target population. For a general population of patients with serious ventricular arrhythmias, the cost per life-year saved of ICD therapy is much higher than is considered favorable when evaluating other forms of therapy.
If we accept that the improvement in survival seen with the ICD should be maintained, how can ICD cost-effectiveness be improved? One approach would be to offer an ICD only to those predicted to have the highest risk of recurrent events. As shown in MADIT and in a pooled analysis of data from CIDS, AVID, and the Cardiac Arrest Study Hamburg,3 events are more frequent and ICD benefits more marked in patients with the most severe left ventricular dysfunction. However, these patients also have higher hospitalization and mortality rates due to heart failure, and total costs are likely to remain high.
An alternate approach would be to try to drive down the costs of ICD therapy. This could be done in several ways. One approach is to extend battery life so that the devices last longer. Although the manufacturers have made significant strides in this area, they have been limited by the simultaneous desire to decrease device size. Since the battery occupies a large fraction of the ICD’s volume, these goals are in conflict. Improvements in defibrillation technology, which would permit routine use of lower defibrillation energies, will be necessary to solve this problem.
A more attractive alternative would be to change the way in which ICD’s are manufactured, marketed, and supported. Until now, manufacturers have competed aggressively to incorporate the latest enhancements into their ICD stock. New models are released several times per year. Since device and software changes are so frequent, extensive support by manufacturers’ representatives is required by most implanting centers. This rapid model turnover was accepted by physicians since size and functionality improvements have been dramatic. However, future changes are unlikely to result in such important clinical differences and a lower cost unit that did not require extensive support could make ICD therapy much more cost-attractive. This will be particularly important if ICD therapy is going to become a standard approach for both the primary and secondary prevention of sudden death.
1. Mushlin AI, et al. Circulation. 1998;97:2129-2135.
2. Larsen GE, et al. Circulation. 1997;96:(Suppl 1):77A.
3. Connolly SJ, et al. Eur Heart J. 2000;21:2071-2078.