Patients getting more aggressive hypertension therapy in a new study achieved significantly lower systolic blood pressure rates and were much less likely to die from heart-related conditions compared with patients on standard therapy. But the implications of the findings are complicated by the practical challenges of sustaining the more aggressive approach.
The study, published Monday in the New England Journal of Medicine, is a follow-up to preliminary results of the Systolic Blood Pressure Intervention Trial, known as Sprint, released in September.
Those early results indicated that lowering systolic blood pressure to a rate of 120 rather than the standard target of 140 reduced the relative risk of heart attack, heart failure and stroke by nearly a third and the risk of death by almost a quarter. The results were so significant researchers ended the study years earlier than planned.
While some experts say the findings should change how blood pressure is managed in the U.S., others counter that aggressive management could prove challenging for providers. Achieving stricter blood pressure targets would require increased use of combination drug therapies as well as additional staff resources for more frequent patient visits and monitoring.
Clinical guidelines generally recommend that adults maintain blood pressure rates of 120/80 or less. The top number is the systolic measure, which shows how much pressure is in the arteries as the heart beats. The bottom number, the diastolic reading, shows the pressure between heartbeats. Typically, more attention is given to the systolic reading, which is a major risk factor for cardiovascular disease, according to the American Heart Association. Measures that top 140/90 are considered too high.
While blood pressure control has improved in the U.S., national goals are still not being met, according to the Centers for Disease Control and Prevention. The agency estimates that direct medical expenditures for high blood pressure treatment cost the nation roughly $8 billion each year, plus an additional $3 billion in lost productivity.
The Sprint trial, led by Dr. Jackson Wright, director of the clinical hypertension program at University Hospitals Case Medical Center in Cleveland, included 9,361 patients from 120 clinical sites in the U.S. and Puerto Rico. The trial included patients aged 50 and older who had high blood pressure, but did not have diabetes, prior stroke, or polycystic kidney disease. Patients were randomly assigned to receive either the standard therapy (to get their systolic BP rates to 140 or less) or intensive therapy (to get the systolic rates to 120 or less).
After the first year, the mean blood pressure in the intensive treatment group was about 121/69, compared with about 136/76 in the standard therapy group. The relative risk of death from cardiovascular causes was 43% lower for patients in the intensive therapy group and for heart failure the relative risk was 38% lower.
While, the rate of serious adverse events—such as abnormally low blood pressure, acute kidney injury and renal failure—occurred more frequently in the intensive therapy group, the authors say the relative risk was low.
Other studies have generated similar conclusions in recent years. A meta-analysis published this month in the journal Lancet looked at data from 19 clinical trials published between January 1950 and November 2015. That study found patients who had received more intensive blood pressure-lowering treatment had mean blood pressure levels of 133/76, compared with 140/81 in the less intensive treatment group. They also had 14% fewer major cardiovascular events.
Inadequate data on the risks versus benefits of systolic blood-pressure targets below 150 has caused some controversy about setting appropriate adequate systolic blood pressure goals for older patients with hypertension, according to the authors of the Sprint trial.
The new study “provides evidence of benefits for an even lower systolic blood-pressure target than that currently recommended in most patients with hypertension,” they wrote.
Other investigators in the study were from Wake Forest School of Medicine, Case Western Reserve University, the University of Utah, the University of Alabama at Birmingham and the Memphis (Tenn.) VA Medical Center.
However, because patients with diabetes were excluded, the authors and others say it is hard to say whether the findings can be generalized to broader populations.
“It doesn't apply to most patients we're seeing,” said Dr. Kenneth Lin, associate professor of family medicine at Georgetown University School of Medicine. “There are a lot of patients with high blood pressure who also have diabetes, and it's not clear from this study whether it's worth treating them to the low targets.”
Of the 29 million people in the U.S. who have diabetes, more than 42% are over the age of 45, according to the American Diabetes Association. Two-thirds of people with diabetes also report having high blood pressure or taking a prescription medication to lower blood pressure.
The study also focuses on drug intervention. Unless you go from “being a couch potato to a marathon runner,” people with extremely elevated blood pressure generally need medication to control blood pressure, said Lin, who is also chair of the subcommittee on clinical practice guidelines for the American Academy of Family Physicians.
However, lifestyle changes are also important, as patients who eat right and exercise may taker fewer of the blood-pressure lowering drugs. “Before we rush and put everybody on a bunch of medications, we want to think about ways to be more successful at motivating people to make lifestyle changes,” he said.
The study's authors also note that keeping blood pressure rates lower than 140/90 is only achieved in about half of the general U.S. population, suggesting “that control even to that level is challenging.”
Achieving a systolic rate of 120 or lower would therefore be more demanding and time-consuming for both patients and providers, and would necessitate increased medication costs and clinical visits.
In the study the patients were followed every three months during the first year and every four months after that, explained Wright. “Whether this can be achieved outside of study and how many fewer visits will be required is still not clear.”
But “deeply ingrained behaviors are difficult—but not impossible—to change,” Dr. Aram Chobanian of the Boston University School of Medicine wrote in commentary posted with the new study. A broad-based national effort with strong political support would be needed, Chobanian wrote.
