AP, November 10, 2008
The lives of nearly 8,000 black Americans could be saved each year if doctors could figure out a way to bring their average blood pressure down to the average level of whites, a surprising new study found. The gap between the races in controlling blood pressure is well-known, but the resulting number of lives lost startled some scientists.
“We expected it to be big, but it was even larger than we anticipated,” said the lead author, Dr. Kevin Fiscella of the University of Rochester School of Medicine & Dentistry.
The study, released Monday in the Annals of Family Medicine, is being called the first to calculate the lives lost due to racial disparities in blood pressure control.
Fiscella said he believes steps can be taken to erase that gap. But a second article in the same journal found that racial differences in blood pressure treatment persisted in England despite a national health system that provides equal access to care.
Doctors may not be providing proper care, but some black patients may not be taking prescribed medicines or following medical advice, said Christopher Millett of the Imperial College of London.
The study suggesting 8,000 black lives are lost due to uncontrolled blood pressure is based on earlier research that finds that about 40 percent of black adults have high blood pressure, compared with about 30 percent of whites.
Fiscella and his colleague, Kathleen Holt, made a series of calculations. They took estimates of how each point of increased blood pressure affects the likelihood of death, and put it in a formula that included the difference in black and white blood pressure readings.
Those differences caused about 5,500 extra deaths from heart disease and about 2,200 deaths from stroke each year.
The second study, done in England, looked at the electronic medical records of about 8,900 patients in southwest London, who are covered by that country’s national health insurance system.
Researchers found black patients with high blood pressure had significantly higher readings than white or Asian patients, even though blacks were prescribed more medications.
The researchers also looked at patients who were sick with one or more conditions like heart disease, kidney disease and diabetes. They found that blood pressure control was much worse in blacks than whites.
Patients’ failure to regularly take their medicine may be one factor. Another may be that certain medications work better for blacks, but some doctors may be overlooking that difference, said Millett, a consultant in public health for Imperial College.
[Editor’s Note: “Racial Disparity in Hypertension Control: Tallying the Death Toll,” by Kevin Fiscella and Kathleen Holt, “Ethnic Disparities in Blood Pressure Management in Patients With Hypertension After the Introduction of Pay for Performance,” by Christopher Millett, Jeremy Gray, Alex Bottle, and Azeem Majeed, and “Examining Racial and Ethnic Disparities in Health and Hypertension Control,” by David Satcher (an editorial on the two studies) are all available as HTML or PDF files together with tables and appendices here.]
In a multi-ethnic population-based group of 3,303 adults, half of whom were African American, a low potassium level in the urine correlated with high blood pressure, regardless of the level of salt (sodium) in the diet or cardiovascular risk factors.
This observation “supports the hypothesis that dietary potassium deficiency plays an important role in the development of high blood pressure,” Dr. Susan Hedayati, of the University of Texas Southwestern Medical Center in Dallas, told Reuters Health.
“The association was stronger in African Americans than non-African Americans,” which suggests possible racial differences in the development of high blood pressure, also referred to as hypertension, and its relationship with to potassium levels in the diet, added Hedayati, who reported the findings over the weekend at the American Society of Nephrology’s annual meeting in Philadelphia.
The overall prevalence of hypertension was 36 percent. In addition to having lower levels of potassium in the urine, individuals with hypertension were older, heavier and more likely to be African American. Hypertensive subjects also had lower glomerular filtration rates, which correlates with poor kidney function.