Cardiac Rehabilitation
In addition to benefiting a sense of well-being, there is an economic benefit that accrues from participation in cardiac rehabilitation programs. During a 3-year follow-up (mean of 21 months) after coronary events (58% of events were coronary bypass operations), per capita hospitalization charges were $739 lower for rehabilitated patients compared with nonparticipants ($1,197 + 3,911 versus $1,936 + 5,459, P = 0.022).
Coronary Artery Bypass Graft (CABG)
Cost-Effectiveness of CABG
CABG represents a major investment for society, with an initial hospital cost of around $30,000 applied to more than 300,000 patients annually in the United States alone (around 10 billion dollars). It is most appropriate to consider the cost of CABG surgery compared with other medical treatment modalities with regard to cost-effectiveness. Definitive data for such a comparison are sparse, and multiple assumptions must be made. The most reasonable system of analysis appears to be an estimation of the dollars spent per quality-adjusted life-year gained ($/QALY). In general, a cost-effectiveness of $20,000 to $40,000/QALY is consistent with other medical programs funded by society, such as hemodialysis and treatment of hypertension. A cost of under $20,000/QALY would be considered particularly cost-effective, while a cost greater than $60,000/QALY would be considered expensive. (Note: The dollar amounts given here are in 1993 dollars).
A widely quoted analysis of the cost-effectiveness of CABG surgery was compiled in 1982 utilizing data gathered from the then available randomized trials comparing medical therapy with coronary artery bypass. The cost of coronary bypass is relatively constant, whether it is conducted for left main disease or for single-vessel disease.
Cost-effectiveness is excellent when the procedure is applied to patient subgroups for whom the benefit in terms of survival or relief of symptoms compared with medical therapy is great (as it would be, for example, in a patient with severe angina and triple-vessel disease). The cost-effectiveness of CABG becomes inordinately poor, however, when the benefit in terms of survival is marginal and there are few symptoms in the preoperative patient. These conclusions are depicted in Figure 12 in the original guideline document, and examples are presented in Table 18 in the original guideline document. Cost-effectiveness for coronary bypass in patients with left main disease is exceptionally good at $9,000/QALY. It is similarly quite attractive in patients with 3-vessel disease, at $18,000/QALY. If one considers the cost-effectiveness of coronary bypass in 2-vessel disease, one study found that the presence or absence of left anterior descending (LAD) disease was very important. Because CABG surgery is particularly effective in relieving angina, its cost-effectiveness, even in patients with single-vessel disease, is not prohibitive if that patient has severe angina. In the patient without angina or with only mild angina, however, the cost of coronary bypass per QALY was prohibitive in this analysis, exceeding $100,000 for patients with 2-vessel or 1-vessel disease.
It is not surprising that coronary bypass surgery is cost-effective in exactly those groups of patients in whom survival and/or symptomatic benefit is demonstrable. Most important, within these subsets the cost-effectiveness of coronary bypass compares favorably with other generally accepted medical therapies.
Cost Comparison With Angioplasty
The cost-effectiveness of angioplasty is dependent on the pre-angioplasty symptoms of the patient in the same way that CABG surgery is so dependent, particularly in subgroups in whom revascularization cannot be shown to have a survival benefit compared with medical therapy (i.e., in single-vessel disease). Because it relieves angina, angioplasty for single-vessel-disease patients with severe angina is estimated to have a cost-effectiveness of $9,000/QALY. In patients with only mild angina, however, angioplasty in the setting of LAD single-vessel disease is estimated to have a poor cost-effectiveness of $92,000/QALY.
A direct comparison of the cost of angioplasty and coronary bypass surgery for selected patients with multivessel disease (i.e., those patients for whom either therapeutic modality was considered appropriate) has been made in the randomized trials of angioplasty versus CABG. In general, the cost analyses of randomized trials have revealed that the initial cost of angioplasty is about 50 to 65% of the initial cost of bypass surgery. The incremental cost of repeated procedures during the follow-up period has led to a cumulative cost of angioplasty that approaches the cumulative cost of bypass surgery at 3 years. The Emory Angioplasty versus Surgery Trial (EAST) found that the 3-year inpatient cost of angioplasty was 94% of that of bypass surgery. The Randomized Intervention Treatment of Angina (RITA) Trial, which included a large number of patients with single-vessel disease, found that the 2-year cumulative cost of angioplasty was 80% of the cost of coronary bypass. The Bypass Angioplasty Revascularization Investigation (BARI) trial conducted a prospectively designed analysis of the comparative cost of the 2 procedures from a subgroup of the participating centers, comprising a total of 934 of the 1,829 patients enrolled. The mean initial hospital cost of angioplasty was 65% of that of surgery, but after 5 years the cumulative cost of initial surgical therapy was only $2,700 more than the cumulative cost of initial angioplasty (around a 5% difference). Because the surgical cohort had a higher overall 5-year survival, the cost of this survival benefit could be calculated. It was found to be $26,000/y of survival benefit for surgical therapy of 2-and 3-vessel disease (in patients for whom either angioplasty or surgery was considered appropriate initial therapy). As considered in the previous section, this incremental cost for double- and triple-vessel disease is within the range of costs for generally accepted therapies. It is notable that this cost of incremental benefit does not consider the benefit of coronary bypass in terms of relief of angina during the follow-up interval, which was demonstrated in each of these 3 trials (Bypass Angioplasty Revascularization Investigation, Emory Angioplasty versus Surgery Trial, and Randomized Intervention Treatment of Angina). If this factor were included, the cost-effectiveness of CABG for incremental benefit in these selected patients with multivessel disease ($/QALY) would be <$26,000.
Previous considerations of both patient benefit and cost-effectiveness have suggested that angioplasty is less effective for patients with more advanced disease. Data gathered at Duke University has shown that there is a significant cost gradient for angioplasty as the extent of disease increases (related to repeated procedures whose instance may be reduced by stents), which is not apparent for coronary bypass.
The use of drug-eluting stents in percutaneous revascularization will require a re-evaluation of cost-effectiveness considerations. The initial procedure is considerably more expensive (equaling the cost of CABG in many patients with multivessel disease), but the recurring cost of reintervention for restenosis will be dramatically reduced. Cost-effectiveness will depend on pricing of stents, utilization rates of the more expensive stents, and efficacy. All of these factors are evolving rapidly.
Cost Reduction in Coronary Bypass
Estimates presented in the previous portion of this section suggest that coronary bypass has been cost-effective in the last 2 decades. Initiatives to decrease the length of stay by using clinical pathways and standardized fast-track protocols have reduced hospital costs. Indeed, the estimates made by Weinstein and Stason are distinctly dated: improvements in outcomes and shortened lengths of hospitalization are likely to have considerably improved the cost-effectiveness of CABG (and angioplasty) since 1982.
Studies from the 1980s suggested that by concentrating CABG procedures into high-volume institutions, the overall cost of providing coronary surgical revascularization would be reduced owing to efficiencies of scale. Shahian et al studied this question and found no relationship between either hospital size or annual CABG case volume and cost of performing bypass surgery.
A major innovation has been the introduction of off-bypass CABG, which has reduced the postprocedure length of stay in some centers to between 2 and 3 days. In some centers, this has led to a total 3-month cost for single-vessel coronary bypass that is not significantly different from the total 3-month cost for angioplasty of single-vessel disease. Considering the favorable long-term patency of an internal mammary artery (IMA) graft to the LAD, the cost reductions possible with off-bypass CABG may improve the relative cost-effectiveness of coronary bypass compared with either medical therapy or percutaneous techniques, particularly for symptomatic, proximal LAD disease.