The study is the first ever to compare data from a state that requires public reporting of angioplasty results -- New York -- with data from a state without public reporting -- Michigan. It reveals some striking differences, though it can't show a direct cause-and-effect relationship between public reporting and doctors' selection of patients.
The study, which is being published in the June 7 issue of the Journal of the American College of Cardiology, was performed by University of Michigan Cardiovascular Center researchers in collaboration with researchers from the State University of New York at Stony Brook.
Overall, the New York patients who received angioplasties to open clogged heart arteries were far less likely than Michigan patients to have underlying or acute conditions that raised their risk of dying before they left the hospital. And Michigan angioplasty patients were twice as likely as New York patients to die in the hospital.
But when the researchers corrected for the fact that Michigan patients were much sicker on average than the New York patients before their angioplasties, they found that there was no difference in overall death risk between the two states. Because the states have similar heart disease patterns, the team concluded that the difference in patient selection might be due to the presence of public reporting in New York.
The study team was led by Mauro Moscucci, M.D., FACC, who directs interventional cardiology at U-M and for nearly a decade has led an angioplasty quality-improvement project funded by Blue Cross Blue Shield of Michigan.
The grant and data from that project, called the BCBSM Cardiovascular Consortium, made it possible for Moscucci and his colleagues to perform the new comparison study. The study is based on data from about 80,000 angioplasty patients: 11,374 treated at eight Michigan hospitals, and 69,048 treated at 34 New York hospitals.
"Public reporting of angioplasty outcomes has been seen as a way to improve accountability, and to drive efforts to improve quality," says Moscucci. "But these data suggest that physicians may be selecting patients who are least likely to bring down their grade, so to speak. Our results also drive home the need for optimal risk adjustment of the data used in public reporting, so that there is an apples-to-apples comparison that takes into account a patient's risk as well as his or her outcome."
In the last decade, angioplasties have become a common, minimally invasive way to open the arteries that surround the heart, without surgery. Millions of people with coronary artery disease (clogged or narrowed heart arteries) have had them. The procedure involves a long, slender catheter that is threaded through a patient's large blood vessels into the area around the heart, where X-ray images guide doctors in opening blocked or narrowed vessels.
The procedure can be performed both on a scheduled basis and under emergency circumstances such as a heart attack. Conditions such as diabetes, kidney problems, lung disease, prior stroke or vascular disease, as well as factors like patient age, gender and smoking habits, are all known to affect the risk that an angioplasty patient will suffer a complication or die before leaving the hospital.
As the procedure has become more common and its benefits have been demonstrated, there have been many efforts to improve angioplasty care so that every patient has the best possible shot at a successful procedure with few complications. The Michigan project, for example, has boosted survival and reduced complications greatly by pooling data and giving doctors guidance on how best to minimize the risks of the procedure for different patients.
But a few states have opted to make those kinds of data public, in an effort to help patients assess doctors or hospitals based on their individual volumes and results. In New York, angioplasty and heart bypass surgery results have been publicly available since the early 1990s.
The new study is based on New York data from the calendar years 1998 and 1999 that were published in January 2003. The Michigan data are from the same time period. In all, 32 percent of patients in the study were women, and the average age was 63. New York patients were slightly older than Michigan patients, and more likely to have high blood pressure.
But the Michigan angioplasty patients had a significantly higher incidence of kidney problems, diabetes, lung disease, vascular problems beyond their hearts and congestive heart failure. They were also much more likely to have had at least one previous angioplasty, suggesting a history of significant coronary artery disease. They were also more likely than New York patients to receive blood thinners or nitroglycerin just before their angioplasty; these drugs are recommended in some high-risk patients to prevent blood clots and blood vessel spasms during and after the procedure.
The Michigan patients were much more likely to have their angioplasty performed soon after being treated for an emergency condition: heart attack, cardiac arrest or cardiogenic shock, a dangerous and often fatal condition in which the heart fails to pump enough blood to the body.
Given these differences in risk factors, Moscucci says, it's not entirely surprising that the Michigan patients were much more likely than the New York patients to die before they left the hospital. But the researchers were surprised at the lack of a mortality difference between the two states once the patients' risks were adjusted using mathematical calculations called logistic regression modeling.
"The fear of public reporting of higher mortality rates may be driving patient selection in New York, but this analysis demonstrates that mortality is not different once you adjust for risk factors," he says. "As the trend toward public reporting grows, and patients and insurers increasingly base their choices on public data, we must make sure that proper risk adjustment makes those data as representative as possible."
Moscucci notes that the new paper echoes the findings of an anonymous survey of New York angioplasty providers published earlier this year, in which nearly 80 percent said that the public reporting of mortality statistics influenced their decisions about performing angioplasties on critically ill patients, such as those with cardiogenic shock. And 83 percent agreed that patients who might benefit from angioplasty might not receive the procedure because of the effect of public reporting.
In addition to Moscucci, an associate professor of internal medicine in the U-M Medical School, the study's authors are Kim Eagle, Eva Kline-Rogers, Dean E. Smith and Sandeep Jani from the U-M CVC, David Share from BCBSM, Anthony DeFranco from McLaren Medical Center in Flint, Mich., Michael O'Donnell from St. Joseph Mercy Hospital in Ann Arbor, Mich., and David L. Brown from SUNY Stony Brook.
New York angioplasty reports are available online from the New York State Department of Health at www.health.state.ny.us/nysdoh/heart/heart_disease.htm#cardiovascular. More information on the Blue Cross Blue Shield of Michigan Cardiovascular Consortium, which has expanded to include 18 Michigan hospitals, is available at http://www.med.umich.edu/opm/newspage/2003/angioplasty.htm.
Journal
Journal of the American College of Cardiology