National Heart, Lung, and Blood Institute Stops Landmark SPRINT Study Early for Benefit: Results Show Lower Blood Pressure Target Greatly Reduces Cardiovascular Disease and Deaths in Older Adults

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Investigators at The University of Tennessee Health Science Center and Memphis Veterans Affairs Medical Center Contribute to National Study Results

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Photo courtesy of the University of Tennessee Health Science Center

When a clinical trial is successful, why stop it early? Because the National Institutes of Health (NIH) wants everyone to know about the benefit of an intervention that works – including the study participants that helped prove the study intervention actually had an impact. That’s what happened in the SPRINT study — Systolic Blood Pressure Intervention Trial.

Today, the National Heart, Lung, and Blood Institute, the NIH institute that sponsored SPRINT, announced they stopped the national SPRINT study about a year earlier than planned in order to quickly disseminate the significant preliminary results.

The reasons for halting SPRINT were all positive. SPRINT found that more intensive management of high blood pressure, below a commonly recommended blood pressure target, significantly reduces rates of cardiovascular disease, and lowers risk of death in a group of adults 50 years and older with high blood pressure. The intervention in this trial, which carefully adjusts the amount or type of blood pressure medication to achieve a target systolic pressure of 120 millimeters of mercury (mm Hg), reduced rates of cardiovascular events, such as heart attack and heart failure, as well as stroke, by almost a third and the risk of death by almost a quarter, as compared to the target systolic pressure of 140 mm Hg.

“This study provides potentially lifesaving information that will be useful to health care providers as they consider the best treatment options for some of their patients, particularly those over the age of 50,” said Gary H. Gibbons, MD, director of the National Heart, Lung, and Blood Institute (NHLBI), the primary sponsor of SPRINT.

“These findings have the potential to change the way we treat hypertension globally,” said Karen C. Johnson, MD, MPH, College of Medicine Endowed Professor in Women’s Health at the University of Tennessee Health Science Center (UTHSC). Dr. Johnson is the principal investigator for the SPRINT study site in the UTHSC Department of Preventive Medicine, and the national vice chair of the SPRINT Steering Committee.

When SPRINT was designed, the well-established clinical guidelines recommended a systolic blood pressure of less than 140 mm Hg for healthy adults and 130 mm Hg for adults with kidney disease or diabetes. Investigators designed SPRINT to determine the potential benefits of achieving systolic blood pressure of less than 120 mm Hg for hypertensive adults 50 years and older who are at risk for developing heart disease or kidney disease.

“We have not known whether lowering systolic blood pressure even below 140-150 mm Hg would be beneficial or harmful, and SPRINT clearly shows the benefits outweigh the harms of treating to much lower levels,” explains William C. Cushman, MD, chief of Preventive Medicine at the Memphis Veterans Affairs (VA) Medical Center and professor of Preventive Medicine, Medicine, and Physiology at UTHSC. For SPRINT, Dr. Cushman is the principal investigator (PI) for the VA Clinical Center Network, overseeing 25 VA clinical sites, chair of the Intervention Committee, and a member of the Steering Committee.

The SPRINT study, which is a randomized clinical trial begun in the fall of 2009, includes more than 9,300 participants age 50 and older, recruited from about 100 medical centers and clinical practices throughout the United States and Puerto Rico. It is the largest study of its kind to date to examine how maintaining systolic blood pressure at a lower than currently recommended level will impact cardiovascular and kidney diseases.

The SPRINT study population is diverse and includes women, racial/ethnic minorities, and the elderly. The investigators point out that the SPRINT study did not include patients with diabetes, prior stroke, or polycystic kidney disease, as other research included those populations.

The UTHSC Department of Preventive Medicine SPRINT site in Memphis, which enrolled and followed 175 participants locally, was one of about 100 SPRINT sites nationwide. Joining Dr. Johnson (PI) in the SPRINT site research were UTHSC co-investigators Drs. Catherine Womack and Keiko Asao. The Memphis VA also had a SPRINT site that enrolled 80 participants with Barry Wall, MD, as the principal investigator.

“At the outset of the trial,” Dr. Johnson said, “we monitored participants closely to determine exactly which blood pressure medication worked best for each individual. We customized the medications, tailoring the blood pressure regimen to achieve optimal, individual results. Once each participant reached his or her lowered blood pressure goal, we saw them every three months. If blood pressure rose above their treatment goal we would see them more frequently to adjust medication. In SPRINT we had the option of using any of the major types of blood pressure medications to lower the pressure.”

“While the results for cardiovascular disease are important, SPRINT was also assessing the impact of intensive blood pressure lowering on the risk for Alzheimer’s disease and other forms of dementia. These results are not yet complete and the SPRINT study will continue to follow all the participants for this important area of healthy aging,” explains Linda Nichols, PhD, who is a member of the national SPRINT MIND working group and a professor in the UTHSC Department of Preventive Medicine. She and Jennifer Martindale-Adams, EdD, associate professor, Preventive Medicine, are the SPRINT MIND principal investigators for the VA Network.

The SPRINT study is also examining kidney disease among the participants; however, those results are also still under analysis and are not yet available as additional information will be collected over the next year.

The primary results of the trial will be published within the next few months.

According to the American Heart Association, nearly 80.7 million American adults have high blood pressure — one in every three. Hypertension greatly increases risk for heart disease and stroke, the first and third leading causes of death in the United States.

The Tennessee Department of Health website states almost 34 percent of all adult Tennesseans were diagnosed with high blood pressure. Furthermore, African-Americans develop high blood pressure more often and at an earlier age than Caucasians and Mexican-Americans.

“Hypertension is a serious problem among Memphis-area residents,” Dr. Johnson continued. “The results of this study have far-reaching implications to help our community prevent disease and extend healthy life. We look forward to quickly communicating the SPRINT results to help inform patient care and the future development of evidence-based clinical guidelines,” she said.

In addition to primary sponsorship by the NHLBI, SPRINT is co-sponsored by the NIH’s National Institute of Diabetes and Digestive and Kidney Diseases, the National Institute of Neurological Disorders and Stroke, and the National Institute on Aging.

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