ASCERT Cost Analysis: CABG More Expensive Than PCI but Offers Better Outcomes

Older patients with multivessel CAD have better outcomes with CABG than with PCI, but the costs of surgery are higher over 4 years and their entire lifetime, according to a study published in the January 6/13, 2015 issue of the Journal of the American College of Cardiology.

The main ASCERT (American College of Cardiology [ACC] Foundation-Society of Thoracic Surgeons [STS] Collaboration on the Comparative Effectiveness of Revascularization sTrategies) trial, published in the New England Journal of Medicine in 2012, showed a long-term survival advantage with CABG over PCI in patients with multivessel disease. The study linked the ACC’s National Cardiovascular Data Registry CathPCI Registry and the STS Adult Cardiac Surgery Database with claims data from the Centers for Medicare and Medicaid Services to assess patients undergoing nonemergent PCI (n = 103,549) or CABG (n = 86,244) for 2- or 3-vessel CAD between 2004 and 2007. Mean age was 73 years in the surgery group and 75 years in the PCI group, and most patients in both groups were male (69% and 58%, respectively).

For the economic analysis and cost assessment, Zugui Zhang, PhD, of the Christiana Health Care System (Newark, DE), and colleagues looked at differences in lifetime costs and cost utility between treatment strategies.

Compared with PCI, costs for CABG were higher for index hospitalization, throughout the 4-year study period, and over patients’ lifetimes (table 1). The difference in index hospitalization cost appeared to drive the continued differences.

 

However, in terms of quality-adjusted life-years (QALYs), CABG came out ahead with 0.2525 years gained during the study period and 0.3801 years gained over a lifetime compared with PCI. Additionally, the lifetime incremental cost-effectiveness ratio of CABG compared with PCI was $30,454 per QALY gained, which is below common benchmarks for societal “willingness to pay,” the authors say.

“It is likely that the accurate estimation of difference in life expectancy was limited,” Dr. Zhang and colleagues acknowledge. “Despite these limitations, the results of our sensitivity analyses were robust, suggesting that the results are unlikely to be severely affected as long as there is a survival benefit of CABG in keeping with the ASCERT results.”

Highlights Gaps in Knowledge

In an accompanying editorial, John A. Spertus, MD, MPH, of Saint Luke's Mid America Heart Institute (Kansas City, MO), commends the authors for what he termed a “statistical tour de force.”

According to Dr. Spertus, selection biases related to the choice of therapy are some of the many unknown factors that may have contributed to the findings in favor of CABG. “Even with propensity scoring and careful patient selection to balance a myriad of measured patient characteristics, factors left unmeasured can bias the results,” he writes. An analysis from 2011 in JACC: Cardiovascular Interventions, for example, documented that refusal by surgeons to perform revascularization increased mortality risk in patients by more than 5-fold, but neither the ACC nor STS registries capture these details, he notes.

Additionally, the extreme divergence in propensity scores in the original ASCERT publication “underscores how truly different the patient populations undergoing PCI and CABG are,” Dr. Spertus says. “As the investigators worked to achieve balance in measured characteristics, they excluded more than 90% of potential participants, substantially limiting their findings’ generalizability.”

Dr. Spertus maintains that revascularization strategy should ultimately be decided by the patient in consultation with his or her heart care team. But such decisions hinge on critical gaps in knowledge such as:

• Little real-world data comparing the health status advantages of each treatment
• Lack of data enabling personalized outcomes estimates
• No method for extrapolating outcomes data to the complex patients typically seen in routine clinical practice

Addressing these gaps “requires that registries collect those outcomes most important to patients, including health status at the time of treatment and over time, so that the research enterprise can build appropriate tools to help support clinical care,” Dr. Spertus says.

 

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Sources:
1. Zhang Z, Kolm P, Grau-Sepulveda MV, et al. Cost-effectiveness of revascularization strategies: the ASCERT study. J Am Coll Cardiol. 2015;65:1-11.
2. Spertus JA. ASCERTing the value of coronary artery bypass graft in stable angina patients: the challenges and potential of observational research to improve care [editorial]. J Am Coll Cardiol. 2015;65:12-14.

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• ASCERT: Long-term Results Favor CABG Over PCI for Multivessel Disease
• ASCERT: CABG More Cost-Effective Than PCI Over Long Term
• At 1 Year PCI More Cost Effective than CABG for Some SYNTAX Patients