Blacks have the highest readings, despite taking medications, study finds
WEDNESDAY, Sept. 23 (HealthDay News) -- Blacks and Hispanics with a history of stroke or coronary artery disease have higher blood pressure than whites, while Hispanics are less likely to be prescribed medications to control it, a new U.S. study shows.
About 63 percent of whites, 58 percent of Hispanics and 40 percent of blacks had blood pressure readings that fell within national guidelines, the researchers found.
"There was a significant disparity in achievement of blood pressure goals among African Americans as compared to whites or Hispanics," said senior study author Dr. Nerses Sanossian, associate director of the Stroke Center at University of Southern California.
The study was to be presented Wednesday at the American Heart Association's High Blood Pressure Research Conference in Chicago.
Researchers evaluated data on blood pressure levels from 517 participants in the National Health and Nutrition Examination Survey who reported having had either a stroke or coronary artery disease. About 12 percent of participants were Hispanic and 25 percent were black.
National recommendations call for most adults to keep their blood pressure under a reading of 140 for the top number and 90 for the lower number, while diabetics should keep it under 130/80.
"The greatest risk factor for having a heart attack or stroke is having a previous heart attack or stroke," Sanossian said. "Blood pressure control is one of the cornerstones of prevention. This is a group of people in whom prevention is really crucial."
Reasons for the disparities may include lifestyle or economic factors, genetics and differences in the quality of health care received, the researchers said.
While blacks and whites reported being prescribed blood pressure medications at similar rates, blood pressure was not as well-controlled in black patients as in white patients.
Black participants had average systolic blood pressure (the upper number in a reading) of 140, compared to 134 among whites. Blacks had diastolic blood pressure (the lower number) of 74, compared to 65 in whites. Both are significant differences, Sanossian noted.
Previous research shows that a systolic decrease of 10 translates into a 31 percent reduction in stroke rate.
"The average person out there has to have their blood pressure controlled, but if you've had a stroke or coronary artery disease you have to have your blood pressure controlled in a much stricter way," Sanossian stressed.
Hispanics and whites had similar systolic blood pressure (133 compared to 134), though Hispanics had higher diastolic blood pressure (72 compared to 65), the researchers noted.
Yet, only 54 percent of Hispanics who'd had a stroke or who had coronary artery disease were taking drugs for hypertension, compared to 77 percent of whites and 76 percent of blacks.
Among stroke survivors, 52 percent of Hispanics were prescribed blood pressure medications compared to 74 percent of whites and 87 percent of blacks. Among Hispanics with coronary artery disease, about 59 percent were taking hypertension medications compared to 80 percent of whites and 74 percent of blacks.
Making sure that minorities get the proper blood pressure medication to get blood pressure under control is of critical importance, said Dr. Rhian M. Touyz, a professor of medicine at University of Ottawa.
Hypertension is more common in blacks than whites and tends to be more difficult to get under control, Touyz said. Blacks tend to suffer more severe complications from high blood pressure at a younger age than other racial groups. Blacks are also more sensitive to the effects of salt in the diet, which can raise blood pressure.
"It's well known that African Americans tend to develop much worse renal complications and stroke than white patients with high blood pressure," Touyz said. "If we can understand better what are the mechanisms that are responsible for the differences in hypertension rates and why the complications are more severe, it will allow us to better treat patients who are black."
In addition, certain high blood pressure treatments don't work as well in blacks. Classes of drugs that inhibit the renin-angiotensin system, which can raise blood pressure when overactive, tend to be more effective in whites, Touyz said.
The data used in the study did not include information about what medications participants were taking or the doses.
Education and outreach programs targeting minorities, along with aggressive screening and treatment for hypertension, would help eliminate some of the disparities, the researchers said.
The American Heart Association has more on high blood pressure.
SOURCES: Nerses Sanossian, M.D., assistant professor, neurology and associate director, Stroke Center, University of Southern California, Los Angeles; Rhian M. Touyz, M.D., Ph.D., Canada Research Chair in Hypertension and senior scientist/professor, medicine, University of Ottawa, Canada; Sept. 23, 2009, presentation, American Heart Association's High Blood Pressure Research Conference, Chicago
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