African-Americans are at a Higher Risk of Dying from Heart Failure than Whites
NEW ORLEANS, LA -- African-Americans appear 30 percent more likely to die from a precursor to complete heart failure than their white counterparts, Duke University Medical Center researchers reported Tuesday.
The findings came from the first study to examine patients with diastolic heart failure, which is an emerging epidemic and appears to affect blacks disproportionately more than whites.
"Previous studies comparing the races have shown that African-Americans with systolic heart failure do much worse," said Dr. Mark East, cardiology fellow at the Duke Clinical Research Institute (DCRI). "However, whites tend to go straight to systolic heart failure as a result of blockages in arteries, while African-Americans progress through heart wall thickening, diastolic heart failure to systolic heart failure, as a result of hypertension. Those studies compared apples to oranges."
East prepared the results of his study for presentation at the 73rd annual scientific sessions of the American Heart Association. A Veterans Administration Health Services Research and Development grant and the DCRI funded the study.
Heart failure is the general term for a condition marked by the inability of the heart to pump oxygen- and nutrient-rich blood throughout the body. Systolic heart failure means that the muscles of the lower heart chambers responsible for pumping blood cannot keep up with the body's demand. Thickening of these same heart chambers that leads to abnormal relaxation marks diastolic heart failure, which is often a precursor to systolic heart failure. This causes oxygen-rich blood to "back up" in the lungs and not get to the pumping chambers in sufficient amounts.
East concentrated only on those African-Americans and whites with diastolic heart failure. He studied the medical records of 3,303 patients (17 percent were African-Americans) seen at Duke from 1984 to 1996 who had diastolic heart failure, but who still had preserved systolic function.
The researchers found the African-Americans tended to be female (70.9 percent vs. 51.8 percent), younger (age 58 vs. 65), hypertensive (73.4 percent vs. 55.5 percent) and diabetic (32.2 percent vs. 24.2 percent). The researchers controlled for such characteristics as diabetes and hypertension (which African-Americans experience at a much higher rate), age, gender and severity of heart disease, and still found this wide disparity in death rates five years after initial diagnosis.
When the researchers conducted sophisticated statistical analysis to account for all these variables, the large gap persisted, leading East to conclude that the reasons are most likely are many.
"We've got a lot of detailed and revealing medical information about the patients in the records, but what we don't have is what the patients were treated with over time and why physicians choose certain therapies vs. others," he said.
While the researchers say that the study was not designed to uncover the underlying cause for the difference, the researchers believe that it is possibly a combination of genetics as well as treatment differences, considering this is a condition that is both understudied and physician practice patterns differ by patient race.
This is not the first study of racial differences in heart disease by DCRI researchers. In 1997, they reported that after studying a group of 12,000 patients, African-Americans were 32 percent less likely to received coronary artery bypass grafting operations for clogged arteries, and that they were 18 percent more likely to die within five years, when compared to whites.
"These data send a powerful message to patients and physicians alike," East said. "There is this large disparity that cannot be explained by the medical characteristics of the patients. Clearly, African-Americans do not fare as well, and we need to conduct the research to find out why. Most likely, as in other disorders, we will find that there are a number of issues at work."
While the study was not designed to compare different treatments received by African-Americans and whites, the researchers plan to study practice patterns in the future. At present East and his colleagues are investigating the mechanisms behind diastolic heart failure, by looking at black and white patients with left ventricular hypertrophy.
"This is an important issue that we as a society need to address, and I believe that as we learn more about the genetics of heart disease, and gather more information about physician treatment patterns, we will get to the bottom of this question," East said. "There are physicians out there who believe that African-Americans are different, but if their beliefs are not backed up by data, that can lead to adverse outcomes. We also need more data on all patients with heart failure to make informed decisions when treating patients with this devastating condition."
Joining East in the current study were DCRI colleagues Dr. Eric Peterson, Linda Shaw, Dr. Judy Battle, Wendy Gattis and Dr. Christopher O'Connor.