Blacks May Get Off-Pump CABG from Less-Experienced Hands

NEW YORK, Jan. 12 -- For reasons that are unclear, black patients in New York State who had a coronary bypass procedure in 1999 were more likely than whites to have it without a cardiopulmonary pump -- but by surgeons not well experienced in the demanding technique.

According to a registry of 15,313 coronary artery bypass graft procedures in New York State in 1999, a disproportionate rate of off-pump procedures were performed on blacks by a relatively large number of low-volume surgeons, compared with a smaller number of high-volume surgeons.

At a time when off-pump CABG was still relatively new and performed mostly by a small cadre of cardiac surgeons, 31% of black patients, 23% of whites, and 20.7% of people of other racial and ethnic backgrounds underwent off-pump CABG (P<0.0001).

Both blacks and whites were equally likely to have off-pump procedures performed by high-volume surgeons -- that is, surgeons who did more than 18 such procedures over a year.

But blacks that year were significantly more likely than whites to undergo an off-pump procedures performed by surgeons who were relatively new to the technique, having done fewer than 18 such operations over one year, reported Dana Mukamel, Ph.D., of the University of California at Irvine, and colleagues in New York, in the Journal of Health Services Research & Policy.

Yet the data, said the authors and others who considered the results, don't automatically translate into a conclusion that less experienced surgeons were using black patients as training material.

Dr. Mukamel and colleagues categorized each of the 15,313 coronary artery bypass graft patients into one of six race/ethnicity groups:

• White non-Hispanic
• White Hispanic
• Black non-Hispanic
• Black Hispanic
• Other non-Hispanic
• Hispanic.

Race and ethnicity were determined by the provider, not the patients.

After they adjusted for clinical characteristics and coronary anatomy, the authors found that blacks treated by surgeons with low volume off-pump procedures were 1.9 times (P<0.01) more likely to have off-pump surgery compared with whites treated by the same surgeons. There were no significant differences between blacks and whites treated by high-volume surgeons, however.

Other studies have revealed racial disparities in health in general and in cardiac care in particular, the authors noted. For example, among patients with similar clinical characteristics, African Americans are less likely than whites to undergo cardiac catheterization or other reperfusion therapy, and are less likely to undergo CABG than whites -- with one apparent exception: off-pump CABG.

"In contrast to what we typically find in terms of racial disparity, with this particular technology blacks are more likely to receive it at higher rates than whites," Dr. Mukamel, a professor of medicine, said in an interview. "That's surprising, and it obviously raises the question why. But that's what the data say, and what the data also say is that this is concentrated among surgeons who don't perform many surgeries."

In an accompanying editorial, Tom Treasure, M.D., a thoracic surgeon at Guy's Hospital in London, and Artyom Sedrakyan, M.D., Ph.D., of the U.S. Agency for Healthcare Research and Quality, wrote that the findings raise questions about racial disparities in health care and the possibility of racial bias in selection of procedures.

"Is it conceivable that during the phase of adopting the technically more exacting 'off-pump' method of performing coronary artery bypass grafting, New York surgeons practiced on their black patients?" they asked. "That is the implication of the findings of Mukamel and colleagues."

But neither the editorialists nor Dr. Mukamel were willing to lay the cause of the disparity with certainty at racisms' door.

"One possibility is that there are differences in the patients' that these physicians are seeing; not every patient is appropriate for the off-pump surgery," Dr. Mukamel said. "We had a unique dataset that allows us to control for many of the differences between patients, but there still could be differences that are not accounted for in the analysis."

"There is the possibility that physicians offer these technologies at the same rate to both black and white patients, but the patients who are more well educated, more savvy, might be asking follow-up questions like 'How experienced are you in this procedure,' and when they hear the physician is not experienced they may turn it down," she continued. "Patients who are less savvy may not know to ask those questions, and so will just accept the recommendations of the physician. So it's not the physician in this [scenario] that's discriminating, it's the communication that affects it."

In a previous study, Dr. Mukamel and colleagues had also shown that African Americans have less access to high-volume cardiac surgeons, regardless of whether they were enrolled in HMOs or fee-for-service health plans.

It's also possible, said Dr. Treasure and Dr. Sedraykan, that factors not included in the dataset, such as hospital volume, may have had an undetected influence.

"In our analysis of the Healthcare Cost and Utilization Project database, low-volume hospitals were much more likely to perform off-pump surgery than high-volume hospitals, perhaps reflecting financial and organizational incentives," they wrote. "The precarious existence of low-volume hospitals may encourage them to offer something new."

Peter W. Groeneveld, M.D., an assistant professor of medicine at the University of Pennsylvania and a core faculty member of the Veteran's Affairs Center for Health Equity Research and Promotion, studies the diffusion of health care technology with an emphasis on economic and racial equity implications. In an interview seeking comment, he agreed that the explanation for the differences in surgical rates and surgeon volume may be less sinister than they might appear at first blush.

"The specter is raised of experimentation on minorities, and while that is certainly a concern, this otherwise surprising finding of a higher number of black receiving an innovative procedure compared to whites -- because it's usually the other way around -- may have an easier explanation," he said.

"When whites were told that they were good candidates for off-pump CABG, they just went and found a high volume provider," Dr. Groeneveld continued. "Whites go to high volume providers because they shop around, whereas blacks have less opportunity to shop around, or even if they wanted to shop around, they have fewer tools with which to do it, because they can't get access to information that's out there such as volume of surgeries done by cardiac surgeons."