The NHLBI-supported ASCERT study (ACCF-STS Database Collaboration on the Comparative Effectiveness of Revascularization Strategies) published in the New England Journal of Medicine (abstract) and Circulation (two abstracts) was highlighted in our press release. It is an example of how large-scale observational comparative effectiveness research, which looks at the advantages and disadvantages of various interventions for specific groups of patients in order to improve health, can supplement data from randomized clinical trials and provide information to help patients and their caregivers make decisions. I wanted to take a moment to reflect on the key implications of this study.
ASCERT analyzed data from nearly 190,000 older adults with stable coronary heart disease who underwent coronary artery bypass grafting (CABG), also known as bypass surgery, or non-surgical percutaneous coronary intervention (PCI), also known as coronary angioplasty, to improve blood flow to the heart muscle. CABG is a more invasive procedure than PCI; the potential risks of a major surgical procedure must be balanced against potential benefits, especially for patients who may be frail and have other medical complications. While no difference in survival was found at one year, at four years there was significantly lower mortality with CABG than with PCI (16.4 percent vs. 20.8 percent). The survival benefit of CABG is seen with all subgroups analyzed.
This study shares all the limitations of other observational studies, but is a real-world analysis of outcomes, which can help guide decisions. Other observational studies have suggested a benefit to CABG, but the magnitude of the sample size in this study adds considerably to the discussion. The findings are also consistent with the four-year findings from the randomized SYNTAX trial (article—requires free membership to access), which compared bypass surgery with drug-releasing stents in patients with severe coronary disease. The ASCERT study investigators have provided patients and health care providers with information to help guide decision-making about revascularization procedures for coronary heart disease, taking into account the patient's individual risk profile, circumstances, and preferences.
ASCERT was funded by the American Recovery and Reinvestment Act of 2009 (award RC2HL101489) as part of the $400 million allotted to the NIH specifically for comparative effectiveness research. ASCERT fulfilled both goals outlined in the Act by comparing disease treatment outcomes and by using preexisting data resources to generate new knowledge. The study team produced its robust findings by linking clinical information from the Society of Thoracic Surgery's Adult Cardiac Surgery Database with data from Medicare claims. It demonstrates the power of combining the efforts of professional societies, government payers, and federal funding agencies.
Data from observational studies like ASCERT continue to supplement that from randomized clinical trials as we strengthen the evidence base for the best care for patients. Definitive answers to the question, "Which procedure is optimal for which patient at what time?" will continue to require large, often difficult and expensive randomized trials. We are attempting to design more cost-effective ways of conducting such studies. In the meantime, this modest investment of Recovery Act funds has provided important data for patients, their doctors, and their families to help all involved make better informed decisions.