EVALUATING AND IMPROVING THE COST-EFFECTIVENESS OF THE IMPLANTABLE CARDIOVERTER-DEFIBRILLATOR

The implantable cardioverter defibrillator (ICD) is an expensive, wide ly used device for severe ventricular arrhythmias. Marginal cost-effec tiveness analysis is a technique to examine the incremental cost of tr eatment strategy in relation to its effectiveness. In this study, we u sed this technique to analyze the cost-effectiveness of the ICD compar ed with that of electrophysiology (EP)-guided drug therapy and examine d ways in which it may be improved. We analyzed Michigan Medicare disc harge abstracts (1989 to 1992) and local physician visit, test, and IC D charges. Effectiveness was from 218 previously described patients wi th ICDs in whom the time of first event (first appropriate shock or de ath) was determined and presumed to represent ''control'' (EP-guided d rug therapy) mortality. We assumed a 4-year life cycle for the ICD gen erator and 3,4% operative mortality and used a 5% discount to present value. Data were analyzed in a 1-month cycle Markov decision model ove r a 6-year horizon, and results were updated to 1993 dollars. ICD effe ctiveness was an increase in discounted mean life expectancy of 1.72 y ears. Cost-effectiveness was $31,100/year of life saved (YLS). Results were minimally or modestly sensitive to variations in preoperative mo rtality; resource use; consideration only of patients with ICDs who we re receiving any antiarrhythmic drug or specifically amiodarone; and t o a decrease in the percentage of first shocks that would equal death without the ICD until the assumed percentage decreased to < 38%. At ej ection fraction of < 0.25 and greater than or equal to 0.25, cost-effe ctiveness was $44,000/YLS and $27,200/YLS, respectively, and without p reimplant EP study was $18,100/ YLS. Cost-effectiveness of the endocar dial ICD in preliminary analysis was $25,700/YLS. Sensitivities were s imilar to those of the epicardial ICD, as was improvement in value in patients with ejection fractions greater than or equal to 0.25 and wit hout preimplant EP study, for whom cost-effectiveness was $14,200/ YLS . In conclusion, use of first-discharge data provides a method of dete rmining ICD cost-effectiveness, which is consistent with that of other techniques. The endocardial ICD, which is now the device predominantl y used, is somewhat more cost-effective than the epicardial, but becom es highly so in patients with ejection fractions greater than or equal to 0.25 and in particular when hospital length of stay is reduced by elimination of the preimplantation EP test. Recent reductions in lengt h of stay with routine implantation of the endocardial device appear a lso to bring cost-effectiveness to this rather favorable level.