Economic evaluation of sirolimus-eluting stents

Abstract

Background: Sirolimus-eluting stents have recently been shown to reduce the risk of restenosis among patients who undergo percutaneous coronary intervention (PCI). Given that sirolimus-eluting stents cost about 4 times as much as conventional stents, and considering the volume of PCI procedures, the decision to use sirolimus-eluting stents has large economic implications.

Methods: We performed an economic evaluation comparing treatment with sirolimus-eluting and conventional stents in patients undergoing PCI and in subgroups based on age and diabetes mellitus status. The probabilities of transition between clinical states and estimates of resource use and health-related quality of life were derived from the Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease (APPROACH) database. Information on effectiveness was based on a meta-analysis of randomized controlled clinical trials (RCTs) comparing sirolimus-eluting and conventional stents.

Results: Cost per quality-adjusted life year (QALY) gained in the baseline analysis was Can58,721 dollars. Sirolimus-eluting stents were more cost-effective in patients with diabetes and in those over 75 years of age, the costs per QALY gained being 44,135 dollars and 40,129 dollars, respectively. The results were sensitive to plausible variations in the cost of stents, the estimate of the effectiveness of sirolimus-eluting stents and the assumption that sirolimus-eluting stents would prevent the need for cardiac catheterizations in the subsequent year when no revascularization procedure was performed to treat restenosis.

Interpretation: The use of sirolimus-eluting stents is associated with a cost per QALY that is similar to or higher than that of other accepted medical forms of therapy and is associated with a significant incremental cost. Sirolimus-eluting stents are more economically attractive for patients who are at higher risk of restenosis or at a high risk of death if a second revascularization procedure were to be required.

Fig. 1: Markov model, showing cost and clinical outcomes after percutaneous coronary intervention (PCI) with stenting in 6-month intervals. After initial PCI, patients are at risk of clinical restenosis over the first year. During this year, they may progress through 5 discrete health states: 1) alive with no clinical restenosis (i.e., event-free), 2) clinical restenosis as determined by the need for a subsequent coronary artery bypass graft (CABG), 3) clinical restenosis as determined by the need for repeat PCI, 4) repeat catheterization with no subsequent revascularization procedure (defined as no PCI or CABG in the ensuing 3 months) and 5) death. Restenosis is considered to occur only in the first year after initial PCI. Thereafter, patients have an ongoing long-term risk of death. CATH = catheterization.

Fig. 2: Scenario analyses. All analyses compare the base case, in which the cost per quality-adjusted life-year (QALY) gained with the use of a sirolimus-eluting stent rather than a conventional stent with PCI is Can$58 721. Each horizontal bar represents the cost per QALY gained in the described scenario, in which 1 or more input values is varied. For example, if the baseline restenosis rate is changed to the RAVEL (RAndomized study with the sirolimus-eluting VELocity balloon-expandable stent4) restenosis rate, the cost per QALY decreases to $54 176. *Varying estimates of 7-day mortality and clinical-event rates in patients in the cohort of the Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease (APPROACH). SIRIUS = study of the SIRolImUS-eluting stent, HRQOL = health-related quality of life.

Fig. 3: Scenario analysis simulating more closely a US health care setting. In addition to increasing the costs of care by 50%, the restenosis rate and the 30-day mortality associated with CABG and PCI were changed to those reported in US settings (shown in the figure). In the baseline analysis, the restenosis rate was 14.2%, the 30-day mortality after CABG 3.1% and the 30-day mortality after PCI 1.4%.