Changes in the recommendations about high blood pressure, stroke prevention and heart-disease prevention are being driven by researchers from North Carolina, which, as a state, has one of the highest rates of cardiovascular disease in the country.
By Stephanie Soucheray
One out of every three Americans has high blood pressure. Or do they?
The U.S. National Heart, Lung and Blood Institute put into question that oft-cited Centers for Disease Control and Prevention statistic earlier this spring when a panel announced new guidelines for treating blood pressure. Now, for adults over the age of 60, the treatment goal of blood-pressure medications and lifestyle intervention will be 150/90, 10 points higher than previous guidelines.
“These new guidelines were controversial, because not everyone on the panel agreed with them,” said Ann Marie Navar-Boggan, a cardiology fellow at Duke University School of Medicine.
Navar-Boggan just published a paper in the Journal of the American Medical Association that looks at the implications of the new guidelines, the first change to blood-pressure recommendations since 2003.
Historically, good blood pressure is a reading at or below 120/80, and until March physicians were expected to begin treatment for high blood pressure when adult patients had consistent readings above 140/90. In North Carolina, the United Health Foundation estimates that 30 to 40 percent of the adult population have blood pressure above 140/90.
Navar-Boggan and colleagues quantified how the new threshold reclassifies Americans with hypertension by using more than 16,000 blood-pressure readings from the National Health and Nutrition Examination Survey (NHANES) conducted by the CDC.
According to the study, 13.5 million adults whose blood pressure was considered uncontrolled now have numbers within the blood-pressure target. U.S. adults considered eligible for hypertension treatment would decrease from 40.6 percent under the old guidelines to 31.7 percent under the new guidelines.
Navar-Boggan said that 5.8 million of those adults were on medication. While she said that the new guidelines are no reason to flush your blood-pressure pills down the drain, they do open up some options for patients who had side effects from medication.
“These guideline are a departure, but they reflect a general increasing knowledge in the area,” said Navar-Boggan.
Lowering pressure a ‘good thing’
Lowering blood pressure has always been the goal for stroke victims, except those with poor collateral blood-vessel formation near the site of stroke. For years, medical folk wisdom thought these patients should “ride high” with blood pressure to prevent another stroke.
“The thinking was that if you have a pipe that’s partially blocked, you increase pressure to force more water through the blockage,” said William Powers, a neurologist at UNC-Chapel Hill.
Powers just published a paper in Neurology that reverses this thinking. He found that lowering blood pressure in these patients helped prevent a second stroke by 22 percent.
“I was surprised by the findings,” he said. “I thought lowering blood pressure would be good for the heart and brain, but I didn’t necessarily think it would prevent a second stroke.”
Using PET scans, Power looked at 91 patients with poor collateral flow; only three of the 40 patients with low to normal blood pressure suffered a second stroke, while 10 of the 51 with high blood pressure had another stroke.
Powers said this study helps offer guidance in the clinic. “There’s a fear in the absence of data that you could make a good argument either way in terms of letting blood pressure ride high,” he said. “Now we know for certain that lowering blood pressure is a good thing.”
Besides blood-pressure monitoring, tracking cholesterol levels is a gold standard in monitoring and preventing heart disease. Last November, the American Heart Association established new guidelines for blood cholesterol, and Duke biostatistician Michael Pencina took existing data to quantify their potential impact.
The new cholesterol guidelines see half of Americans over the age of 40 as candidates for statin therapy.
“The new guidelines increase statin use by 12.8 million between the ages of 40 and 75,” said Pencina, whose results were published in the New England Journal of Medicine. Almost half, or 56 million people, are recommended to use statins, which is an 11 percent increase.
“When you break it [down] by age, it turns out the new recommendations don’t differ very much in younger years,” said Pencina. “It’s over 60 where the vast majority of increase happens.”
He said the staggering statin recommendations are not a uniquely American problem; such recommendations have also been made in the Netherlands and Eastern Europe.
“Statins are quite safe, but they do have uncommon side effects,” said Pencina. “The question is: Are we comfortable with a situation in which half of the nation between 40 and 75 is on a pharmaceutical treatment?”
He said that increasing statin therapy among this population could prevent as many as 500,000 heart attacks and strokes in the next decade.
Prevention of disease is something Peg O’Connell thinks about when she thinks about blood pressure and cholesterol in North Carolina. O’Connell used to be a member of the Justus-Warren Heart Disease Task Force, which makes recommendations about cardiovascular health to the General Assembly.
“We’ve made remarkable progress,” said O’Connell. She said that 20 years ago, North Carolina was third in the nation for cardiovascular disease and is now seventh. That change, which follows national trends in lowering the number of deaths caused by coronary disease, is often attributed to treating high blood pressure and cholesterol with medicine.
Still, heart disease is the second-leading cause of death in the state and stroke is the fourth. And according to the Justus-Warren task force, cardiovascular disease cost the state almost $6 billion in hospital charges in 2010.