 "The mystery that is blood pressure")
Almost half a century after rigorous studies showed medicines that lower blood pressure prevent heart attacks, strokes and deaths, researchers still do not know just how low blood pressure should go. More than 58 million Americans take these drugs, but this fundamental question remains unresolved.
"We all know treating hypertension is good, but we don't know how aggressive we should be," said Michael Lauer, the director of the Division of Cardiovascular Sciences at the National Heart, Lung and Blood Institute.
The institute is seeking definitive answers as part of its mission to drive down deaths from cardiovascular disease, continuing the decades-long plunge in mortality rates from this leading killer.
The results of a large and rigorous study, called Sprint, are expected in 2017. Researchers are following 9,000 middle-age and older adults with high blood pressure. Half were randomly assigned to get their systolic pressure - the top number that measures pressure when the heart contracts - to below 120, while the others were to get to below 140. The study will measure not just heart attacks, strokes and kidney disease, but also effects on the brain. Do people think better and avoid dementia with lower pressure?
In the meantime, doctors are making decisions in a fog of uncertainty.
What about a patient like Glenn Lorenzen, 67, whose systolic pressure was a frightening 220 in October? On a chilly day in December at the cardiovascular clinic at the Boston Veterans Affairs hospital, he had received the good news that drugs and weight loss had lowered his reading to 124. Should he be happy? Should he aim to be below 120? Or should he ease up on the medications a bit and let his pressure drift toward 140 or even 150?
One school of thought says blood pressure rises with age to push more blood into the brain. Another says high blood pressure damages the brain, perhaps causing silent ministrokes.
"We don't know which is right," said David Reboussin, a biostatistician at Wake Forest University who is a principal investigator for the new federal study.
The lack of evidence is at the heart of a dispute that is partly an artifact of the way thinking on blood pressure evolved. When drugs to lower blood pressure came on the market in the 1950s, many doctors did not know if they should prescribe them. They thought systolic pressure should be 100 plus a person's age. The conventional wisdom was that blood vessels stiffen with age, so higher pressure helped push blood through them.
Many early clinical trials did not even address systolic pressure, the focus today. Instead, they looked at diastolic pressure, the lower number.
"The general thinking - incorrectly - was that as you get older, the systolic naturally goes up" to supply the brain with blood, said William C Cushman, the chief of preventive medicine at the VA Medical Center in Memphis.
It was only in 1991 that the first study on systolic pressure was published. It and subsequent research concluded that the treatment goal should be a level below 150 in order to prevent heart attacks, heart failure and strokes. Almost no studies examined the outcomes at lower goals.
So doctors and guideline makers have a conundrum, Cushman said. Guidelines from experts are all over the map. A panel appointed by the National Heart, Lung and Blood Institute suggests a systolic pressure below 150 for those older than 60. The American Heart Association and other groups say it should be under 140.
That sort of inconsistency leaves many physicians in a quandary. Lorenzen's doctor at the Boston VA, J Michael Gaziano, considers a patient's overall risk and is an evangelist for losing weight and exercising to boost the effects of blood pressure drugs. He lives that way himself, following a Mediterranean diet low on meat and engaging in running and cross-country skiing.
Lorenzen, who has had two heart attacks, is still heavy, but he is one of Gaziano's star pupils. He has lost 60 pounds and exercises most days. When his pressure used to be 200 and above, he said his head hurt "like a wicked sunburn."
"Your blood pressure is headed in a good direction, better than I would have expected," Gaziano told him. "I get an A," Lorenzen said proudly.
Hospitals and medical practices evaluate doctors by how well patients' pressures adhere to guidelines and often penalise them financially when patients are not adherent.
But Gaziano said the grading system that targets a single value as a measure of success is flawed. "If a patient starts with a pressure of 180 and gets it down to 145, I get a bad mark. I did not succeed. But if a patient goes from 140 to 139, I succeeded."
© 2015 The New York Times
"We all know treating hypertension is good, but we don't know how aggressive we should be," said Michael Lauer, the director of the Division of Cardiovascular Sciences at the National Heart, Lung and Blood Institute.
The institute is seeking definitive answers as part of its mission to drive down deaths from cardiovascular disease, continuing the decades-long plunge in mortality rates from this leading killer.
The results of a large and rigorous study, called Sprint, are expected in 2017. Researchers are following 9,000 middle-age and older adults with high blood pressure. Half were randomly assigned to get their systolic pressure - the top number that measures pressure when the heart contracts - to below 120, while the others were to get to below 140. The study will measure not just heart attacks, strokes and kidney disease, but also effects on the brain. Do people think better and avoid dementia with lower pressure?
In the meantime, doctors are making decisions in a fog of uncertainty.
What about a patient like Glenn Lorenzen, 67, whose systolic pressure was a frightening 220 in October? On a chilly day in December at the cardiovascular clinic at the Boston Veterans Affairs hospital, he had received the good news that drugs and weight loss had lowered his reading to 124. Should he be happy? Should he aim to be below 120? Or should he ease up on the medications a bit and let his pressure drift toward 140 or even 150?
One school of thought says blood pressure rises with age to push more blood into the brain. Another says high blood pressure damages the brain, perhaps causing silent ministrokes.
"We don't know which is right," said David Reboussin, a biostatistician at Wake Forest University who is a principal investigator for the new federal study.
The lack of evidence is at the heart of a dispute that is partly an artifact of the way thinking on blood pressure evolved. When drugs to lower blood pressure came on the market in the 1950s, many doctors did not know if they should prescribe them. They thought systolic pressure should be 100 plus a person's age. The conventional wisdom was that blood vessels stiffen with age, so higher pressure helped push blood through them.
Many early clinical trials did not even address systolic pressure, the focus today. Instead, they looked at diastolic pressure, the lower number.
"The general thinking - incorrectly - was that as you get older, the systolic naturally goes up" to supply the brain with blood, said William C Cushman, the chief of preventive medicine at the VA Medical Center in Memphis.
It was only in 1991 that the first study on systolic pressure was published. It and subsequent research concluded that the treatment goal should be a level below 150 in order to prevent heart attacks, heart failure and strokes. Almost no studies examined the outcomes at lower goals.
So doctors and guideline makers have a conundrum, Cushman said. Guidelines from experts are all over the map. A panel appointed by the National Heart, Lung and Blood Institute suggests a systolic pressure below 150 for those older than 60. The American Heart Association and other groups say it should be under 140.
That sort of inconsistency leaves many physicians in a quandary. Lorenzen's doctor at the Boston VA, J Michael Gaziano, considers a patient's overall risk and is an evangelist for losing weight and exercising to boost the effects of blood pressure drugs. He lives that way himself, following a Mediterranean diet low on meat and engaging in running and cross-country skiing.
Lorenzen, who has had two heart attacks, is still heavy, but he is one of Gaziano's star pupils. He has lost 60 pounds and exercises most days. When his pressure used to be 200 and above, he said his head hurt "like a wicked sunburn."
"Your blood pressure is headed in a good direction, better than I would have expected," Gaziano told him. "I get an A," Lorenzen said proudly.
Hospitals and medical practices evaluate doctors by how well patients' pressures adhere to guidelines and often penalise them financially when patients are not adherent.
But Gaziano said the grading system that targets a single value as a measure of success is flawed. "If a patient starts with a pressure of 180 and gets it down to 145, I get a bad mark. I did not succeed. But if a patient goes from 140 to 139, I succeeded."
© 2015 The New York Times