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Cost-Effectiveness of Implantable Cardioverter Defibrillators Relative to Amiodarone for Prevention of Sudden Cardiac Death

Douglas K. Owens, MD, MSc; Gillian D. Sanders, AB; Ryan A. Harris, MS; Kathryn M. McDonald, MM; Paul A. Heidenreich, MD; Anne D. Dembitzer, MD; and Mark A. Hlatky, MD
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Copyright ©2004 by the American College of Physicians


Ann Intern Med. 1997;126(1):1-12. doi:10.7326/0003-4819-126-1-199701010-00001
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Background: Implantable cardioverter defibrillators (ICDs) are remarkably effective in terminating ventricular arrhythmias, but they are expensive and the extent to which they extend life is unknown. The marginal cost-effectiveness of ICDs relative to amiodarone has not been clearly established.

Objective: To compare the cost-effectiveness of a third-generation implantable ICD with that of empirical amiodarone treatment for preventing sudden cardiac death in patients at high or intermediate risk.

Design: A Markov model was used to evaluate health and economic outcomes of patients who received an ICD, amiodarone, or a sequential regimen that reserved ICD for patients who had an arrhythmia during amiodarone treatment.

Measurements: Life-years gained, quality-adjusted life-years gained, costs, and marginal cost-effectiveness.

Results: For the base-case analysis, it was assumed that treatment with an ICD would reduce the total mortality rate by 20% to 40% at 1 year compared with amiodarone and that the ICD generator would be replaced every 4 years. In high-risk patients, if an ICD reduces total mortality by 20%, patients who receive an ICD live for 4.18 quality-adjusted life-years and have a lifetime expenditure of $88 400. Patients receiving amiodarone live for 3.68 quality-adjusted life-years and have a lifetime expenditure of $51 000. Marginal cost-effectiveness of an ICD relative to amiodarone is $74 400 per quality-adjusted life-year saved. If an ICD reduces mortality by 40%, the cost-effectiveness of ICD use is $37 300 per quality-adjusted life-year saved. Both choice of therapy (an ICD or amiodarone) and the cost-effectiveness ratio are sensitive to assumptions about quality of life.

Conclusions: Use of an ICD will cost more than $50 000 per quality-adjusted life-year gained unless it reduces all-cause mortality by 30% or more relative to amiodarone. Current evidence does not definitively support or exclude a benefit of this magnitude, but ongoing randomized trials have sufficient statistical power to do so.

Figures

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Figure 1.
Schematic representation of the decision model.Figure 2Figure 2Figure 2Figure 2

The square node represents a decision to use one of three treatment regimens: implantable cardioverter defibrillator (ICD) only, amiodarone only, or amiodarone-to-ICD (see Methods). Circles represent chance nodes. After a regimen is chosen, the patient enters a Markov tree (denoted by rectangles containing circles and an arrow). A patient who receives the ICD-only regimen enters the Markov tree only if he or she survives ICD implantation. The Markov trees represent the clinical events that can occur during each 1-month period as a patient is followed until death. For example, a patient receiving the ICD-only regimen is at risk each month for ventricular tachycardia (VT), ventricular fibrillation (VF), nonarrhythmic cardiac death, and noncardiac death. If none of these events occur, the patient remains “well” for the 1-month period. A patient who is well at the end of a month reenters the Markov tree. The braces represent subtree notation and indicate that a patient who has VT or VF enters the arrhythmia subtree, which is shown in the top panel of . Subtrees are denoted by rounded rectangles. Patients receiving the amiodarone-only or the amiodarone-to-ICD regimen are at risk for VT, VF, nonarrhythmic cardiac death, noncardiac death, and toxicity from amiodarone. If toxicity from amiodarone occurs, the patient enters the amiodarone toxicity subtree ( , bottom). For the amiodarone-to-ICD treatment regimen, the events that occur after a patient has an arrhythmia depend on the type of arrhythmia experienced. A patient who has VT enters the amiodarone-to-ICD VT subtree ( , upper middle); a patient who has VF enters the amiodarone-to-ICD VF subtree ( , lower middle).

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Figure 2.
Decision model subtrees.Top.Figure 1Upper middle.Lower middle.Bottom.

The subtrees show events that may occur to patients during a 1-month cycle. The arrhythmia subtree. A patient who receives the implantable cardioverter defibrillator (ICD)-only regimen or the amiodarone-only regimen and has ventricular arrhythmia enters the arrhythmia subtree. If the patient survives the arrhythmia, he or she may have neurologic impairment or may become well (have no neurologic sequelae). A patient who is well continues to receive the assigned therapy (Rx) and returns to the appropriate Markov node (see ) to begin another 1-month period. The amiodarone-to-ICD ventricular tachycardia (VT) subtree. Fifty percent of patients who survive ventricular tachycardia without neurologic impairment receive an ICD; the other 50% continue to receive amiodarone. The amiodarone-to-ICD ventricular fibrillation (VF) subtree. All patients who have VF receive an ICD, as denoted by the chance node with only one branch (ICD implantation). The amiodarone toxicity subtree. This represents the events that may occur in patients in whom amiodarone toxicity occurs. A patient may have an acute side effect, withdraw from treatment, or die as a result of toxicity. Acute toxicity represents time-limited symptoms that require evaluation and management (for example, thyroid dysfunction) but not discontinuation of amiodarone therapy.

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Figure 3.
Sensitivity analyses.Top.Bottom.

Base-case estimates for each sensitivity analysis are indicated by arrows. Effect of the increased survival advantage produced by an implantable cardioverter defibrillator (ICD) on the cost-effectiveness of therapy with an ICD compared with amiodarone therapy. The frequency of generator replacement substantially affects marginal cost-effectiveness because the devices are expensive.

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Figure 4.
Effect of cost of implantation of an implantable cardioverter defibrillator (ICD) on cost-effectiveness.

The middle line shows the base-case cost estimate for ICD implantation; the top and bottom lines show how cost-effectiveness varies if implantation costs are increased or decreased by 20%.

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