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(Circulation. 2000;101:1067.)
© 2000 American Heart Association, Inc.
Current Perspective |
From Medtronic Inc, Minneapolis, Minn, and Charles River Associates Inc, Boston, Mass (G.K.B.).
| Abstract |
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Methods and ResultsArticles published between 1990 and 1997 were screened for cost-effectiveness analyses of ICD versus antiarrhythmic drug therapy. Randomized clinical trials, prospective and retrospective studies, and economic models were included. These studies report incremental cost-effectiveness ratios ranging from cost savings of $13 975 per life-year saved (LYS) to an incremental cost of $114 917 per LYS for ICD therapy. Differences were due to study type, cost-reporting methodology, ICD technology used, and length of follow-up. Assuming current technology and physician practice patterns, we find that ICD total therapy costs may break even in 1 to 3 years.
ConclusionsRecent literature suggests that ICDs are a cost-effective therapy for management of life-threatening ventricular tachyarrhythmias. The advent of new technology and patient management practices should further improve the cost-effectiveness of ICD therapy. Future studies of ICD cost-effectiveness should address the implications of truncated follow-up periods and quality of life.
Key Words: cost-benefit analysis cardioversion defibrillation
| Introduction |
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This article reviews the recent literature concerning economic-outcomes analyses of ICDs compared with conventional therapy, ie, antiarrhythmic drug therapy, in the management of VT/VF. In the first section, we discuss the fundamentals of clinical economics and some problems associated with defining costs. In the second section, we summarize the current literature on the comparative economics of ICD and conventional therapies and present break-even cost analyses. The third section discusses the future of ICD therapy, including expected changes in both technology and physician practice patterns, as it might affect the economics of VT/VF management. The final section addresses pitfalls to avoid and issues to consider for future ICD economic outcomes studies.
| Economic Outcomes Analysis: Key Issues |
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Much of the variability in economic-outcomes analysis stems from differences in the determination and measurement of the costs and benefits of treatment. The costs of treatment are calculated as follows: total expected costs of treatment equals initial therapy costs plus continuing therapy costs plus expected costs of treating side effects and complications.
For ICDs, the implant procedure and device cost represent initial costs; battery replacement and periodic monitoring are continuing costs; and the probability of lead or perioperative complications times the cost of correction are expected costs of treating side effects and complications. For antiarrhythmic drug therapy, an electrophysiological (EP) study, drugs, and the associated hospital stay constitute initial costs. Regular prescription refills and routine patient management are continuing costs, and the probability of another cardiac event or drug toxicity times the cost of treatment are expected costs of treating side effects and complications. The expected incremental costs of treatment with ICD therapy are equal to the difference between the expected total costs of treatment with ICD therapy and the expected total costs of treatment with antiarrhythmic drugs.
Defining Costs
There is no single definition of cost suitable for all
analyses and decision makers. Costs of treatment based on the
actual costs of the medical resources used are of greatest interest to
the hospital, staff model health maintenance organizations, and
others who receive a fixed payment, either capitated or based on
diagnosis-related groups, for services provided. For payers and
providers who accept patients on some form of fee-for-service basis,
costs of treatment based on charges and reimbursement rates are most
relevant. Costs of treatment that include nonmedical costs, such as the
loss of income or productivity and the imputed costs of
denigrations in quality of life, are most important to the patient, the
patients family and employer, and society in general.
Another critical, and common, difference among economic-outcomes studies is the time period over which costs are tracked. This is especially problematic in evaluations of high-initial-cost interventions, such as ICDs. Because of the implant procedure and device cost, ICD therapy has a high initial cost but relatively low continuing costs. In contrast, antiarrhythmic drug therapy has much lower initial costs but higher continuing costs, reflecting the long-term cost of purchasing pharmaceuticals and the possibly higher likelihood of future events and side effects requiring costly emergency care and hospitalization. One European study examined the effects of ICD implantation on rehospitalizations in patients previously receiving a range of antiarrhythmic therapies. The results showed a reduction in frequency (from 3.23 to 0.88 per year) and total duration (from 32.94 to 9.31 days per patient per year) of rehospitalizations with the ICD.5
An economic-outcomes analysis of ICD therapy that considers only a short time frame may severely overstate a relative cost disadvantage or fail to demonstrate potential cost savings because of a short follow-up period that does not capture all the continuing costs of the alternative therapy. A calculated break-even time may be reported to mitigate the problems associated with the length of the follow-up period. The break-even time is often expressed as the expected number of months or years before the initial cost disadvantage of a therapy has been offset by its lower continuing costs.
Present value is another technique commonly used to account for differences in the timing of costs and outcomes. Present value recognizes that the costs and health outcomes incurred today are more significant to the decision maker than those that may be incurred in the future. A discount rate is used to measure the present value of future costs and effects. For instance, at a 5% discount rate, costs of $100 expected to be incurred next year would be counted as a present value cost of only $95 today. The higher the discount rate is, the less significant future costs are, and the lower the economic benefit provided by a high initial-cost therapy, such as the ICD, is.
An example of the use of break-even times and discount rates was
calculated from data presented by Kupersmith et
al6 comparing the costs of ICD and antiarrhythmic drug
therapy (see Figure 1
). In this example,
the costs are restated in 1997 dollars with the use of the medical cost
component of the Consumer Price Index.7
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Assuming a present-day scenario that uses an endocardial ICD
without a preimplant EP study, we calculate an initial hospitalization
charge of $45 584. The initial hospitalization charge for EP-guided
antiarrhythmic drug therapy is $35 478. These 2 costs are shown as the
year 0 costs in Figure 1
. Continuing therapy costs and life
expectancy are discounted at 5%. On the basis of the information
reported, the average annual charges of continuing treatment are
assumed to be $21 561 for endocardial ICD therapy and $31 640 for
antiarrhythmic drug therapy, represented by the slopes of
the lines in Figure 1
. The mean life expectancy after
hospitalization is 3.78 and 2.06 discounted life-years for ICD and
antiarrhythmic therapy, respectively. After the mean life expectancy is
reached, the graphed cost curves continue as dotted lines. The distance
between the 2 cost curves at any time represents the difference
between the total costs of the respective therapies. The break-even
time is 1.0 years, the point where the 2 cost curves cross.
Types of Economic-Outcomes Analysis
There are 4 distinct types of economic-outcomes
analysis: cost-identification analysis (CIA),
cost-effectiveness analysis (CEA), cost-utility
analysis (CUA), and cost-benefit analysis (CBA). Table 1
discusses each analysis. The
primary difference among the methods is the manner in which the
benefits of treatment are recognized and accounted for. A number of
texts and articles provide in-depth discussions of these
methods.8 9
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Sensitivity Analysis
Economic-outcomes analysis should always include an
evaluation of the sensitivity of reported results to changes in the
cost and benefit parameters. These "what-if" scenarios
allow readers to customize the analysis for their particular
experience, practice, or institution. For example, the
cost-effectiveness of ICDs is dependent on the life expectancy of the
battery within the pulse generator. As the frequency of generator
replacement is decreased as a result of technological advances, the ICD
becomes more cost-effective.
| Economic-Outcomes Analysis: ICD Therapy |
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Articles for review were identified by use of MEDLINE. They were initially selected if published in English between 1990 and 1997 and if they contained the index terms "implantable cardioverter-defibrillator" or "cardioverter defibrillator" and "cost," "economics," or "cost-effectiveness." In addition, abstracts reporting results of 3 recently completed, large, multicenter studies (AVID, CIDS, and CASH) were obtained from conference proceedings from US scientific meetings. Articles retrieved were then screened for CEAs of ICD compared with antiarrhythmic drug therapy. Randomized clinical trials, prospective and retrospective studies, and economic models were included. Of the 24 sources initially identified through index terms on MEDLINE and conference proceedings, 7 passed the screening criteria listed above and are analyzed in this article.
Meta-analysis and meta-regression techniques were not used in this analysis because of the lack of data provided in the studies and the limited number of studies meeting inclusion criteria for our article. Furthermore, the articles did not provide enough detailed information on SEs, CIs, or probability values to derive test-based SEs. In the absence of reliable information to perform a robust meta-analysis, we have synthesized the data in a format that presents the important findings related to economic outcomes.
A summary of the methodologies used in each of the 7 studies is
presented in Table 2
. This table
discloses the type of study, assumptions made, follow-up, and types of
sensitivity analyses performed. The studies are
presented in order of their findings, from most to least
cost-effective for ICDs.
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Figure 2
depicts graphically the base
case, minimum, and maximum cost-effectiveness scenarios from each of
the 7 studies. All results have been restated in 1997 dollars with the
use of the medical cost component of the Consumer Price
Index.7 Cost-effectiveness ranges are adapted from the
Kupersmith et al10 study, which examined
cost-effectiveness for a variety of cardiovascular
disorders and treatment options. Among the scenarios analyzed,
results from AVID11 and Wever et al12 appear
to be outliers. The AVID results may represent an outlier
because of the short follow-up period. The Wever et al results fall
outside the general ranges, most likely because of the high proportion
of therapy changes in the EP-guided strategy group.
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Figure 3
presents a summary of
incremental cost-effectiveness results for the base case of each study
and relevant sensitivity analyses. ICD cost-effectiveness is
sensitive to battery life assumptions, use of a preimplant EP study,
and relative mortality advantage of ICDs over antiarrhythmic drug
therapy. Figure 4
displays incremental
cost-effectiveness results for other cardiovascular
interventions as determined in the Kupersmith et al10
study. With the Kupersmith et al categorization, ICD therapy appears to
be cost-effective, perhaps akin to primary coronary artery
stenting.
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Sensitivity to Battery Life
As evident in Figure 3
, the cost of ICD therapy is
sensitive to battery life, which in turn depends on the type of battery
and the patients requirements for pacing and therapeutic shocks. With
current devices, patients requiring no pacing or therapeutic shocks can
expect an average device longevity of
9 years.13 Device
longevity may decrease to 5 years when continual pacing and monthly
therapeutic shocks are needed.13 New technologies that
allow dual-chamber pacing and shocks have comparable device longevity
profiles.14
A number of published studies examine the effect of improved battery life in their sensitivity analyses.6 15 16 17 18 For example, the MADIT investigators reported cost-effectiveness of $13 311 per life-year saved (LYS) with generator replacement after the 4-year period instead of $28 751 per LYS for potential replacement within 4 years from the base case, a savings of $15 441 per LYS.15 By extending battery life to 8 years (from 2 years in the base case), Larsen et al16 reported savings of $24 219 per LYS.
Break-Even Analyses
We calculated base case break-even periods from 6 of the 7
studies, as shown in Table 3
. Reported
data were insufficient in AVID11 to permit calculation of
the break-even period. In 2 studies, those of Kuppermann et
al19 and Wever et al,12 break-even for the
base case occurs within the reported life expectancy of the ICD cohort.
ICD therapy would be a cost-saving therapy, saving $18 840 (Kuppermann
et al19 ) and $33 733 (Wever et al12 ) if the
average patient on antiarrhythmic drug therapy were to survive as long
as the average patient receiving an ICD. Using additional data reported
by Kuppermann et al, we considered an updated scenario (5-year battery
life and nonthoracotomy implant) that generated a break-even at 2.93
years and total therapy cost savings of $54 426 if the average patient
on antiarrhythmic drug therapy survived as long as the average patient
implanted with an ICD. Today, patients typically receive nonthoracotomy
ICDs with battery longevity
8 years.
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In 2 other studies, MADIT15 and Kupersmith et al,6 the ICD was not expected to break even during the follow-up period or the remaining life expectancy for the base case. ICD therapy did break even in both studies within the follow-up period when new technology and updated patient management techniques, such as nonthoracotomy ICDs, improved battery life, or implantation without a preimplant EP study, were considered. In MADIT,15 considering only endocardial ICDs and base case battery life, the break-even period is 3 years; considering a 4-year battery life, the calculated break-even period is 2.61 years. For these 2 cases, the expected cost savings with ICD implantation over the reported average follow-up period are $4910 and $8928, respectively. In the Kupersmith et al6 study, a scenario using endocardial ICDs without a preimplant EP study yielded a 1-year break-even. This ICD treatment scenario would show total cost savings with ICD implantation of $27 991 based on the reported life expectancy of the ICD group (3.78 years).
In the remaining 2 studies, Larsen et al16 and Owens et al,17 ICD therapy does not break even for the base case. In both, the reported ongoing maintenance costs of ICD therapy were higher than those for the alternative. Owens et al17 referenced published costs from the 1992 Larsen et al16 study and a survey of hospitals in northern California as sources for estimates of annual ongoing costs used in the model. Because the annual ongoing costs were not itemized, we were unable to determine whether the ICD would break even if an alternative patient management scenario were used.
Examining the updated cases in Table 3
reveals a current range
of ICD break-even periods from 1 to 3 years. Emerging patient
management practices, such as elimination of the preimplant EP study,
and technology improvements that increase battery life and allow
nonthoracotomy implantation greatly reduce the required break-even
periods from the base-case calculations, in some cases
77%.
| The Future: ICD Technology and Patient Management |
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A 1996 retrospective analysis compared both postoperative length of stay and charges of patients who received an epicardial compared with a nonthoracotomy lead system, with generator implantation either abdominally or pectorally.20 Average convalescent time was reduced from 11.6 days for epicardial/abdominal implants to 4.6 days for nonthoracotomy abdominal implants and to 2.9 days for nonthoracotomy pectoral implants. Compared with the epicardial/abdominal group, average charges were reduced by 40% in the abdominal group and by 55% in the pectoral group using the transvenous lead system. Both MADIT15 and Kupersmith et al6 also examined scenarios for technology changes from epicardial to endocardial ICD systems. Their results reported savings ranging from $4472 to $6295 per LYS, respectively.
Similar data supporting the cost advantages of the new devices and patient management practices were reported in a study that examined a hypothetical scenario including catheterization laboratory implantation and use of endocardial ICDs.18 The researchers found that total charges over the 27-month average follow-up were lower in the catheterization laboratory scenario, $55 009, compared with either ICD implantation in the operating room under general anesthesia, $69 251, or conventional drug therapy, $77 854.
Other patient management practices that increase ICD cost-effectiveness are elimination of a preimplant EP study, elimination of the predischarge device test, and delivery of conscious sedation rather than attended general anesthesia. Each of these is becoming common practice. Another innovation, painless high-voltage lead impedance testing, available in some newer ICDs, allows monitoring of lead integrity without arrhythmia induction procedures during patient follow-up visits.
Economic Impact of New Technology Adoption
As ICD use becomes more widespread, 2 issues will arise in its
economic evaluation that may lead to decreased cost-effectiveness.
First, inexperienced physicians may overadmit patients to the hospital
for single appropriate shocks, and patients poorly educated about their
devices may admit themselves, fearing their device is not working
properly. A potential increase in the frequency of rehospitalization
was examined in 2 studies6 19 that showed decreased
cost-effectiveness ranges from an additional $3847 to $7333 per LYS. As
patients and physicians become more comfortable with ICDs, this initial
peak in hospitalizations could disappear. Future economic
analyses should account for this learning curve through longer
follow-up and scenario analysis for the postlearning curve
era.
Second, the extension of use into lower-risk patient populations may not exhibit the survival differences noted in existing studies. Owens et al17 have shown that ICD therapy for intermediate-risk patients is less cost-effective than for high-risk patients, with incremental costs of an additional $2000 per LYS. Furthermore, as an increasing number of lower-risk patients receive ICD therapy, ICD studies should incorporate an expanded definition of costs to account for potential quality-of-life differences.
Conclusions
Future studies of the cost-effectiveness of ICD therapy should
address 2 concerns. The first issue is follow-up time as it relates to
the duration of treatment and the likelihood of battery replacement.
Both MADIT and AVID were terminated prematurely after demonstrating
statistically significant mortality advantages in favor of ICD therapy.
Censoring the survival data, however, yields an economic-outcomes
analysis of these trials that is biased against ICD therapy. To
the extent possible, CEAs of ICD therapy should consider the
sensitivity of the results to increases in survival time over the
full course of treatment. Fitting short-term follow-up data in the
context of a longer-term survival model could allow researchers to
consider more fully the potential for ICD therapy to increase average
survival time and reduce incremental costs. An unduly short follow-up
period, however, could also bias results in favor of ICD therapy. If
the cost analysis is truncated just before an expected battery
replacement, the cost-effectiveness of ICD therapy would be overstated
because it would not appropriately account for the significant cost of
battery replacement. The most appropriate solution to this problem may
be to prorate the costs of battery replacement on the basis of the
likelihood of survival and the expected battery life.
The second issue is an expanded definition of costs to include other social costs, such as lost patient productivity and willingness to pay. One study assumes and assigns a quality of life of 0.75 to both antiarrhythmic drug therapy and ICD therapy cohorts but does not examine patient utilities with validated quality-of-life measurement tools.17 No studies have published results adjusted for actual patients perceived differences in quality of life under either ICD or antiarrhythmic drug therapy. Perhaps those patients receiving ICD therapy enjoy a greater sense of security, are confident in the efficacy of their device, and are less subject to lost productivity resulting from repeated attacks of arrhythmia. Alternatively, perhaps these patients are troubled by the risks and potential costs of inappropriate shocks.
Nevertheless, in the case of ICDs, the evidence to date suggests that these devices represent a cost-effective therapy for life-threatening ventricular arrhythmias; ICD therapy is in the range of other well-accepted common therapies for cardiovascular disease. Indeed, the data now strongly support the first-line use of ICDs for treatment of serious arrhythmias in patients with sustained ventricular arrhythmias (AVID, CIDS, and CASH) and those at high risk for lethal ventricular arrhythmias (MADIT). Advancing technology, such as dual-chamber ICDs that have integrated dual-chamber detection and increased specificity for patients with supraventricular tachycardias, and changes in patient management practices should lead to ongoing improvements in the cost-effectiveness of ICD therapy.
| Acknowledgments |
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| Footnotes |
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| References |
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