Cost-effectiveness of percutaneous coronary intervention with drug eluting stents versus bypass surgery for patients with diabetes mellitus and multivessel coronary artery disease: results from the FREEDOM trial

Abstract

Background: Studies from the balloon angioplasty and bare metal stent eras have demonstrated that coronary artery bypass grafting (CABG) is cost-effective compared with percutaneous coronary intervention (PCI) for patients undergoing multivessel coronary revascularization-particularly among patients with complex coronary artery disease or diabetes mellitus. Whether these results apply in the drug-eluting stent (DES) era is unknown.

Methods and results: Between 2005 and 2010, 1900 patients with diabetes mellitus and multivessel coronary artery disease were randomized to PCI with DES (DES-PCI; n=953) or CABG (n=947). Costs were assessed from the perspective of the U.S. health care system. Health state utilities were assessed using the EuroQOL 5 dimension 3 level questionnaire. A patient-level microsimulation model based on U.S. life-tables and in-trial results was used to estimate lifetime cost-effectiveness. Although initial procedural costs were lower for CABG, total costs for the index hospitalization were $8622 higher per patient. Over the next 5 years, follow-up costs were higher with PCI, owing to more frequent repeat revascularization and higher outpatient medication costs. Nonetheless, cumulative 5-year costs remained $3641 higher per patient with CABG. Although there were only modest gains in survival with CABG during the trial period, when the in-trial results were extended to a lifetime horizon, CABG was projected to be economically attractive relative to DES-PCI, with substantial gains in both life expectancy and quality-adjusted life expectancy and incremental cost-effectiveness ratios <$10 000 per life-year or quality-adjusted life-year gained across a broad range of assumptions regarding the effect of CABG on post-trial survival and costs.

Conclusions: Despite higher initial costs, CABG is a highly cost-effective revascularization strategy compared with DES-PCI for patients with diabetes mellitus and multivessel coronary artery disease.

Clinical trial registration: URL: http://www.clinical-trials.gov. Unique identifier: NCT00086450.

Figure 1

CONSORT Diagram. Black boxes represent the modified intention to treat (mITT) population that was the primary analytic population for the economic study. The grey boxes represent the per protocol (PP) population.

Figure 2

Mean cumulative medical costs (lines) and mean annual follow-up costs (bars) in 2010 dollars, for the PCI and CABG groups.

Figure 3

Observed survival through 5 years and predicted survival beyond 5 years for the CABG (solid) and PCI (dashed) groups.

Figure 4

Joint distribution of projected lifetime incremental costs and quality-adjusted life expectancy for CABG vs. PCI based on bootstrap replication of the FREEDOM trial population-- plotted on the cost-effectiveness plane. The white circle represents the estimated mean values (incremental cost = $5392, incremental QALYs=0.663)

Figure 5

Cost effectiveness acceptability curve of CABG vs. PCI, in $/QALY gained (black, solid line) and $/Life year gained (blue, dashed line). The probability that CABG is cost-effective is calculated as the proportion of bootstrap-derived estimates falling below a given cost-effectiveness threshold, is plotted across a range of possible cost-effectiveness thresholds.