Coronary artery disease (CAD) is a major cause of morbidity and mortality in the United States. Despite intensive appraisal, there remain questions regarding the comparative effectiveness of the two forms of coronary revascularization therapy, percutaneous coronary intervention (PCI), and coronary artery bypass graft (CABG) surgery. In the United States, more than 1,000,000 coronary revascularization procedures are performed every year. Some patients are best served with PCI, while others are undoubtedly better served with surgery. Between these two groups, however, lies a large population in which the optimal treatment is not well-defined.
The ASCERT™ (American College of Cardiology Foundation-The Society of Thoracic Surgeons Collaboration on the Comparative Effectiveness of Revascularization sTrategies) Study represents a unique and exciting collaboration between the American College of Cardiology Foundation (ACCF) and The Society of Thoracic Surgeons (STS) to study the comparative effectiveness of PCI and CABG for the treatment of stable coronary artery disease. The ACCF, in partnership with STS, has been awarded a two-year grant by the National Heart, Lung, and Blood Institute of the National Institutes of Health (NIH) to compare catheter-based and surgery-based procedures using existing databases from the ACCF and STS, as well as the Centers for Medicare and Medicaid Services (CMS) 100% denominator file data. By linking these three databases, the study will help physicians make better decisions and improve healthcare for patients with coronary artery disease.
The ASCERT™ Study is designed to compare the long-term effectiveness of the two most common interventions used to treat coronary artery disease; three- to five-year results of bypass surgery will be compared to the results of coronary stents. The outcomes utilized to compare PCI and CABG are: death rates; the need for additional or repeat procedures; rehospitalization; presentation of new cardiac disease conditions; and medication requirements at various time points following revascularization.
The STS Adult Cardiac Surgery Database is the largest cardiac surgery database in the world. It is a multi-institutional clinical registry of cardiothoracic surgery in the United States. The Database has been in use since 1989 and now has participation from 999 centers, which is just over 90% of the cardiac surgery centers in the country. The registry contains clinical information from more than 3.8 million cardiac surgical procedures and provides national benchmarks, trends and risk-adjusted outcomes data.
The National Cardiovascular Disease Registry (NCDR®), an initiative of the American College of Cardiology Foundation®, began in 1997 to help health care provider groups and institutions respond to increasing requirements to document their processes and outcomes of care in the catheterization lab setting. Today, the NCDR® is the most comprehensive, outcomes-based quality improvement program in the United States, including both hospital-based registries and a practice-based program. NCDR® helps participating facilities and other medical professionals to identify and close gaps in quality of care, to reduce wasteful and inefficient care variations, and to implement effective, continuous quality improvement processes. More than 2,200 hospitals nationwide participate in the NCDR® and the registry contains more than 11 million patient records.
Dr. William Weintraub and Dr. Fred H. Edwards are principal investigators on this study. Dr. Weintraub is chair of the ACCF’s National Cardiovascular Data Registry (NCDR®) CathPCI Registry Steering Committee. Dr. Edwards, from The Society of Thoracic Surgeons, is chair of the STS Workforce on National Databases. Duke Clinical Research Institute (DCRI) will provide leadership and also perform the analyses for clinical outcomes and Christiana Care Center for Outcomes Research (CCOR) will perform the analyses for economic outcomes. In addition, PERFUSE Angiographic Core Laboratories and Data Coordination Center will perform detailed angiographic analysis on 2,000 angiograms of patients who have undergone PCI in order to determine their SYNTAX score. Led by Drs. Weintraub and Edwards, a steering committee of investigators representing ACC, STS, DCRI, CCOR, and PERFUSE are responsible for the administration and conduct of this study.
The aims of the ASCERT™ Study are to:
- Create separate PCI and CABG prediction models of death and non-fatal events long-term after initial revascularization in the setting of chronic coronary artery disease.
- Characterize patients undergoing CABG versus PCI by developing propensity scores for CABG in patients undergoing isolated CABG or PCI not in the setting of an acute myocardial infarction. Describe these patients in both groups across the range of their propensity scores.
- Compare long-term survival, hospitalization for MI, renal failure, stroke, and repeat revascularization using propensity score methods.
- Select a random sample of patients undergoing CABG or PCI for detailed angiographic analysis to create a SYNTAX score. In this sample, attempt to model the SYNTAX score based on covariates available in the STS and ACCF databases. Use this data to consider the presence of residual confounding based on angiographic severity defined by the SYNTAX score.
- Assess long-term outcomes by age, gender, co-morbidity, and severity of disease.
- Assess resource use and long-term costs in each group using MEDPAR. The cost and incremental cost-effectiveness of CABG compared to PCI will be considered for the whole matched group and for subgroups as defined above. The outcome will be in cost per life year gained and cost per quality adjusted life year gained.
The ASCERT™ Study will set a standard for combining clinical databases with administrative databases to study comparative effectiveness of therapies in large patient populations as well as help to inform shared decision making between physicians and patients about the best approach for their treatment. The approach used in this project can be adopted by other specialties and their professional societies for comparative effectiveness studies and quality improvement initiatives, and the techniques of analysis should have broad application to the entire field of medicine.
The STS and ACC NCDR® registries have been at the forefront of quality improvement activities in cardiovascular medicine for a number of years. Combined, STS and NCDR® cover virtually the entire spectrum of cardiovascular care. These registries contain detailed information collected prospectively, including demographics, cardiovascular history, patient risk factors, co-morbid illnesses present on admission, interventions, care processes, and risk-adjusted outcomes surrounding specific clinical events.
The ASCERT™ Study has the potential to provide significant new information that may confirm or change current clinical practice. The focus of the research on PCI versus CABG, the use of two of the most prominent clinical registries in the country, and the fact that collaboration between STS and NCDR®covers the entire spectrum of adult cardiovascular disease promises that the results will be of great interest to all physicians. Moreover, the dataset will be large enough to provide sufficient power to examine subgroups. This study will be a model for comparative effectiveness using non-randomized data, permitting extensive assessment of long-term clinical and economic outcomes after coronary revascularization from the largest clinical databases concerning revascularization in the world.