Based on appropriate use criteria, researchers found substantial underutilization and overutilization of coronary revascularization in contemporary clinical practice. Underutilization of coronary revascularization is associated with significantly increased risks of adverse outcomes in patients with appropriate indications, according to a study published online Oct. 10 in the Journal of the American College of Cardiology.
Dennis T. Ko, MD, MSc, of the Institute for Clinical Evaluative Sciences in Toronto, and colleagues reviewed outcomes for a population-based cohort of stable patients undergoing cardiac catheterization for a diagnosis of coronary artery disease (CAD) in one of the 18 cardiac invasive centers in Ontario between April 1, 2006 and March 31, 2007.
The authors randomly selected a sample of 8,972 patients from the Ontario Cardiac Care Network database. Experienced cardiology research nurses reviewed hospital charts focusing on variables that are used in appropriate use criteria. Patients were excluded from the study if they had:
- Acute indications for coronary angioplasty;
- Cardiac catheterization or PCI in the year preceding the index procedure;
- Prior CABG;
- Luminal stenosis of 50 percent of less; or
- Inability to assign appropriateness scores.
The final data set comprised 1,628 patients; the primary long-term outcome measure was a composite of all-cause mortality and recurrent hospitalization for acute coronary syndrome (ACS). Follow-up data were available for all patients through March 31, 2010.
At the time of the coronary angiography, 61 percent of the patients had appropriate indications for coronary revascularization, 20 percent had uncertain indications and 19 percent had inappropriate indications.
Among patients who received revascularization procedures, 68 percent met the appropriateness criteria, 18 percent were uncertain and 14 percent were classified inappropriate.
There were 991 patients who were appropriate candidates for revascularization; of these, 69 percent received revascularization, with more than half of these receiving PCI. Of the 326 patients classified as uncertain candidates, 54 percent received revascularization; PCI was the procedure in 86 percent of these. The researchers classified 311 patients as inappropriate candidates for revascularization; 45 percent underwent a revascularization procedure, primarily PCI (82 percent).
Patients who were deemed appropriate candidates for coronary revascularization had better outcomes if they received revascularization: at three years, 11.8 percent of the group who received revascularization reached the primary endpoint vs. 16.1 percent of those who did not, mortality was 3.8 percent among the group who received revascularization and 9 percent in the group who did not, repeat ACS was 9.4 percent in the former group and 9.9 percent in the latter group.
In the patients classified as uncertain candidates, 8 percent of the revascularization group met the primary endpoint vs. 15.3 percent of those who had medical treatment only; mortality was 2.3 percent in the revascularization group and 12.7 percent in the no procedure group. Repeat ACS was 5.6 percent in the former group and 5.3 percent in the latter group.
In the patients deemed inappropriate, the group that had revascularization met primary endpoints at a rate of 14.2 percent compared with 9.4 percent among the no revascularization group, mortality was 2.8 percent and 5.3 percent respectively, and repeat ACS was 12 percent in the revascularization group and 5.3 percent in the no revascularization group.
The study found both underutilization and overutilization of coronary revascularization among the Ontario sample. More than 30 percent of patients who were appropriate candidates for revascularization did not receive it, while almost 50 percent of the patients who were deemed uncertain or inappropriate candidates did receive it.
The authors referred to a 2011 study indicating that among non-acute patients in the U.S., 50 percent of patients receiving PCI were considered appropriate candidates, 38 percent were uncertain and 12 percent were inappropriate (JAMA 2011;306:53-61).
"Further evaluation is needed to confirm whether discrepancies in appropriateness of coronary revascularization exist and whether they can be attributed to differences in implicit and explicit incentives associated with the different models of healthcare financing between the two countries," the authors wrote.
They also observed higher-risk characteristics and comorbidities among patients who did not receive revascularization, "a pervasive pattern in medicine in which treatment propensity decreases as a result of increasing risk profiles of patients."
The authors pointed out several limitations of their study: The patients were not randomized and therefore the sample may be subject to selection bias; a small sample size; and an inability to determine patients’ preferences regarding whether to undergo revascularization.