Commentators called the study the most important blood pressure research in 40 years. Treating systolic pressure to a target of 120 mm Hg did not cause problems for patients with existing chronic kidney disease although there were some signals for those who did not have the disease at baseline.
Treating blood pressure aggressively, to targets much lower than standard guidelines, trimmed death and cardiac event rates and did not cause problems for those with kidney disease, according to a landmark study first announced in September.
Full results of the National Institutes of Health study, which commenters called the most important blood pressure study in 40 years, were outlined Monday at the American Heart Association (AHA) Scientific Sessions in Orlando, Florida, and simultaneously published in the New England Journal of Medicine.1,2
The Systolic Blood Pressure Intervention Trial, or SPRINT, was stopped early when it was found that aggressively treating high blood pressure (BP) over what had been standard care offered substantial benefits to Americans age 50 years or older: deaths dropped by 25% and other cardiovascular (CV) events dropped by 30%. The study participants all had hypertension and at least one other health risk.
In the study, 9361 men and women with an average age of 67.9 years were randomized to be treated to target their systolic BP to < 140 mm Hg (standard) or to the lower target of < 120 mm Hg. When SPRINT was designed, guidelines called for treating most healthy adults to a systolic BP of at least < 140 mm Hg and those with kidney disease or diabetes to at least < 130 mm Hg.
Treating to a lower standard would require more intensive therapy might offer benefits to patients with existing cardiovascular disease (CVD), but it might also carry risks, especially for patients who had chronic kidney disease (CKD). SPRINT examined these elements, and these details were spelled out Monday at AHA, along with demographic breakdowns and results for the oldest participants.
As explained at a press conference by Paul K. Whelton, MB, MD, MSc, chair of the SPRINT steering committee and an epidemiologist from Tulane University, high systolic BP is a leading risk factor for early mortality or disability found among more than 1 billion people worldwide. While high BP is treatable, there is disagreement on the optimal target level.
“The big question that remains for us is how low to take that blood pressure?” he said.
Trial process. Patients were given standard BP medications; Whelton insisted that no type of therapy was preferred. Patients were monitored every 3 months for 3 months and then monthly after that; Whelton said investigators took care to ensure that this was “not a casual blood pressure reading.”
The trial was meant to last 4 to 5 years, with the primary outcome being the difference in the first occurrence of myocardial infarction, acute coronary syndrome, stroke, heart failure, or CV death.
The standard therapy group achieved a mean systolic BP of 136.2 mm Hg after year 1 while the intenstive group achieved a mean systolic BP of 121.4 mm Hg. Whelton said there was typically a difference of 1 additional medication for the intensive group.
The difference in outcomes began to become apparent after year 1, and on August 20, 2015, the director of the National Heart, Lung, and Blood Institute made the decision to stop the trial after only 3.26 years.
Differences in primary outcomes are large. The number of primary outcomes in the intensive group was 243 compared with 319 for the standard group, for a rate of 1.65 compared with 2.19 per year. Other comparisons were: MI, 97 vs 116, or a rate of 0.65 vs 0.78; stroke, 62 vs 70, or a rate of 0.41 vs 0.47; heart failure, 62 vs 100, for a rate of 0.41 vs 0.67, and CVD death, 37 vs 65, for a rate of 0.25 vs 0.43.
Researchers were concerned about the effect of intensive therapy on persons with CKD. Whelton said there was no difference for those who already had CKD, but were some increased issues for those who did not have kidney problems at baseline. However, he said that the benefit therapy more than outweighed the risks. Benefits showed up across other demographic subgroups as well, including Americans over age 75.
“This story is a triumph, “ said Marc A. Pfeffer, MD, PhD, of Harvard Medical School and Brigham and Women’s Hospital, who served as a commenter on the study. “Our government deserves a lot of credit.” Government has taken lead for decades in funding research to educate physicians about the need to treat high blood pressure, which is challenging because it is a “silent killer.”
No patient, Pfeffer said, is going to thank a physician for prescribing a pill when he isn’t feeling any symptoms.
1. Wright JT, A randomized trial of intensive versus standard blood pressure control (SPRINT). N Engl J Med [published online November 9, 2015]. 2015; doi:10.1056/NEJMoa1511939
2. Whelton PK. Sysotlic Blood Pressure Intervention Trial (SPRINT). Presented at the American Heart Association Scientific Sessions; Orlando, Florida; November 9, 2015; abstract 23696.