Coronary Heart Disease: Bypass Surgery Has Better Outcomes But At Higher Costs Than Stents

Zugui Zhang Interview with:
Zugui Zhang PhD
Value Institute, Christiana Care Health System
Newark, Delaware

MedicalResearch: What is the background for this study?

Dr. Zhang: The strategies of percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG) for revascularization have been compared in randomized clinical trials. Questions still remain concerning the comparative effectiveness of PCI and CABG. The best way to control for treatment-selection bias is to conduct a randomized trial, but such trials often have limited power to evaluate subgroups. More importantly, the results may not be generalizable, since patients are often highly selected. Nonrandomized, observational data from clinical databases can complement data from clinical trials, because observational data, if they are from a larger and more representative population, may better reflect real-world practice.

ASCERT (American College of Cardiology Foundation and the Society of Thoracic Surgeons Collaboration on the Comparative Effectiveness of Revascularization Strategies) was a large observational study designed to compare the long-term effectiveness of CABG and PCI to treat coronary artery disease (CAD) over 4 to 5 years. This study examined the cost-effectiveness of CABG versus PCI for stable ischemic heart disease.

MedicalResearch: What are the main findings?

Dr. Zhang: This study examined the cost-effectiveness of CABG versus PCI for stable ischemic heart disease.   Adjusted costs were higher for CABG for the index hospitalization, study period, and lifetime by $10,670, $8,145, and $11,575, respectively. Patients undergoing CABG gained an adjusted average of 0.2525 and 0.3801 life-years relative to PCI over the observation period and lifetime, respectively. The life-time incremental cost-effectiveness ratio of CABG compared to PCI was $30,454/QALY gained.

This study shows that over a period of 4 years or longer, CABG is associated with better outcomes but at higher cost than PCI among older patients with 2- or 3-vessel CAD. Under the assumption that our analysis has fully accounted for both measured and unmeasured confounding, in patients with stable ischemic heart disease, CABG will often be considered cost-effective at thresholds of $30,000 or $50,000/QALY.

MedicalResearch: What should clinicians and patients take away from your report?

Dr. Zhang: Findings in Our report are consistent with clinical trial data showing a survival advantages of CABG. However, CABG is more expensive than PCI, almost entirely due to the initial cost of the procedure.   These findings are useful in guiding clinical decision making, including shared decision making with patients. If patients and providers do not care much about the costs (such as to Medicare), our findings suggest that there are survival advantages with CABG over PCI, over a period of 4 years or longer.

MedicalResearch: What recommendations do you have for future research as a result of this study?

Dr. Zhang: Analyses that link clinical and administrative databases can be applied to other aspects of patient management to enhance insights from observational studies and clinical registries about the relative value of various options and inform shared decision making between patients and providers.

This study takes an important step in assessing the comparative effectiveness of alternative revascularization techniques (CABG and PCI). It also highlights important gaps in existing data and the challenge of assessing therapeutic effectiveness from observational data. The use of observational data to support shared medical decision making is tantalizingly close. For future research, we recommend that clinicians and researchers should collect data and build tools that patients can use to help make decisions, which are aligned with their personal values and goals.


Zhang Z, Kolm P, Grau-Sepulveda MV, et al. Cost-Effectiveness of Revascularization Strategies: The ASCERT Study. J Am Coll Cardiol. 2015;65(1):1-11. doi:10.1016/j.jacc.2014.09.078.