Poor Patients Twice As Likely To Die From Heart Disease

ATLANTA - In the first analysis of its kind, Duke University Medical Center researchers have shown that the poorest of poor Americans are more than twice as likely to die of severe heart disease than similar patients with higher incomes. Furthermore, it may be that the main explanation comes from what happens in these patients' lives after hospital discharge.

The researchers studied 2,207 patients enrolled in a multi-center clinical trial in which they all received the same standardized treatments. The analysis revealed that patients with an annual household income of less than $10,000 had a 30-day mortality rate 2.6 times higher than those more well off, and a six-month mortality rate 2.1 times higher.

"In a clinical trial, patients are supposed to receive similar care, but actually did not," said lead investigator Sunil Rao, M.D., who prepared the results of the Duke study for presentation today (March 17) at the 51st annual scientific sessions of the American College of Cardiology. "Despite the standardization of many treatments, poverty was associated with a lower rate of some evidence-based medications at the time of hospital discharge and a lower rate of some procedures during the hospitalization.

"After adjusting for these differences, poverty was still associated with a generally worse outcome, suggesting that the situation these patients return to may be responsible," he continued. "It may be that once out of the hospital, these patients return to risky habits such as smoking or bad diet, or more likely they cannot afford the medications prescribed for them to treat their heart disease."

Their findings raise important health-care policy issues, the researchers say, since most of the very poor tend to be elderly. In the current analysis, the average age of the low-income group was 65.

"The elderly, whose numbers continue to grow, are those who are the most impacted by heart disease," Rao continued. "They keep coming to the hospital with heart problems, which we treat and then send them home on medications they may have trouble affording."

Past studies, which have been observational, have shown that poor patients tend to have higher mortality rates after suffering a heart attack. The problem with these studies, the researchers said, is that instead of using solid income numbers to measure socio-economic status, the studies used such "proxies" as education levels or the median income for their ZIP code.

In order to obtain more concrete income data, the Duke researchers mined the results of the economic substudy of the much larger PURSUIT (Platelet Glycoprotein IIb/IIIa in Unstable Angina: Receptor Suppression Using Integrilin Therapy) trial, which enrolled 10,928 patients in a study of a new drug to prevent blood clots from forming in heart attack patients. In a 2,207-patient subanalysis of this multi-center trial, the PURSUIT researchers asked about household incomes, in increments of $10,000.

"This was the first time that this type of information was collected in an American clinical trial in cardiology," Rao said. "Since everyone enrolled in a specific clinical trial receives the same standardized care while in the hospital, this set of data gave us a unique opportunity to look at these economic issues without being clouded by other factors."

Of the 2,207 patients, 22 percent had household incomes under $10,000 per year. They tended to be female, older and have such other ailments as hypertension, diabetes and heart failure. They were also less likely to receive medications that past clinical trials had demonstrated to be effective, and they were also less likely to receive revascularization procedures.

"However, once we controlled for all these risk factors and differences in care, the poor still had a significantly higher short- and long-term risk of having another heart attack or dying," Rao said.

For the past decade, Duke cardiologist Eric Peterson, M.D., senior member of the research team, has been conducting research on discrepancies between outcomes for elderly and African-American patients. He believes that this current study represents a significant step forward in better understanding the complex issues of socio-economic status and outcomes in heart patients.

"What makes the results of this study so important is that within the setting of a clinical trial, you would expect the outcomes to be similar," Peterson said. "We looked at the obvious reason why there might be such a discrepancy -- fewer procedures, less usage of evidence-based medicines, or that they may have been sicker when they enrolled in the trial.

"Now, based on this study, the answers are less clear in that the differences we find are only partially explained by these factors," Peterson continued. "We have to spend more time looking at the larger issue of the continuity of care and long-term compliance issues to ensure that all patients obtain the same outcomes from medical care."

The Duke team has several projects under way to better understand what happens to patients after discharge. In one, they plan to monitor how compliant patients are with their medications 180 days after discharge, as well as finding out if these patients have a solid social support network to take care of them.

The PURSUIT trial was funded by COR Therapeutics, San Francisco, Calif. The Duke Clinical Research Institute supported Rao's analysis.

Other members of the team, all from Duke, are Padma Kaul, Ph.D., Kristin Newby, M.D, Robert Harrington, M.D., and Daniel Mark, M.D.

Note to editors: Dr. Sunil Rao can be reached at (919) 668-7058 or sunil.rao@duke.edu. Dr. Eric Peterson can be reached at (919) 668-8830 or peter018@onyx.dcri.mc.duke.edu.