Does a lower blood pressure goal cut the risk of heart and kidney diseases, stroke, and cognitive decline?
The National Institutes of Health plans to add about 1,750 participants over the age of 75 to its upcoming Systolic Blood Pressure Intervention Trial (SPRINT) to determine whether a lower blood pressure range in older adults will reduce cardiovascular and kidney diseases, age-related cognitive decline, and dementia.
"No large-scale clinical trial has examined the impact of aggressively lowering systolic blood pressure among older adults," said Susan B. Shurin, M.D., acting director of the NIH’s National Heart, Lung, and Blood Institute (NHLBI).
The American Recovery and Reinvestment Act will fund the first two years of the study expansion — called SPRINT-Senior — for $12.7 million. The NIH is providing $30.1 million for the remaining six years of the project.
The NHLBI is the lead NIH funder of the study, which is also supported by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), the National Institute of Neurological Disorders and Stroke (NINDS), and the National Institute on Aging (NIA).
"The SPRINT study and the senior expansion address four of the 10 common causes of death and disability in adults over 75 years: heart disease, stroke, kidney failure, and dementia. The addition of these participants promises to provide useful scientific and public health information on a large and growing segment of the population," added Shurin.
Current clinical guidelines recommend maintaining a systolic blood pressure — the top number in a blood pressure reading — of less than 140 millimeters of mercury (mm Hg) for healthy adults of all ages and 130 mm Hg for adults with kidney disease or diabetes. Two previous trials found that reducing systolic blood pressure in older participants reduced stroke, heart failure, and overall cardiovascular events by more than 30 percent. SPRINT will evaluate the safety and potential benefits or risks of maintaining systolic blood pressure at either less than 140 mm Hg (standard group) or less than 120 mm Hg (treatment group) – a lower target than currently recommended or studied in previous trials.
Announced in 2009, SPRINT is a nine-year study to be conducted in over 70 clinical sites across the United States. Including the 1,750 new SPRINT-Senior participants, approximately 9,250 people age 55 years or older are expected to be enrolled. Participants will have systolic blood pressure of 130 mm Hg or higher as well as a history of cardiovascular disease; be at high risk for heart disease by having at least one additional risk factor, such as a history of smoking or a high blood cholesterol level; or have chronic kidney disease. Over 40 percent of the SPRINT participants are expected to have chronic kidney disease. SPRINT and SPRINT-Senior are examples of comparative effectiveness research, which compares different interventions or strategies to prevent, diagnose, treat, and monitor health conditions in clinical settings. SPRINT enrollment will begin this fall.
Researchers will treat study participants with commonly available medications to achieve their target blood pressure. Those in the treatment group will take an average of three to four medications. Those in the standard group will take an average of two medications. Participants will be seen in clinics every month at the beginning of the study and less frequently as they reach their blood pressure targets. The study will include standard tests for determining the health of the heart, kidneys, and brain.
The NINDS and the NIA support SPRINT Memory and Cognition IN Decreased Hypertension (SPRINT-MIND), a substudy of SPRINT that focuses on the impact of lowering systolic blood pressure on cognitive decline and development of dementia. The study will also include brain imaging to measure treatment effects on brain structure. SPRINT-Senior participants will also be included in SPRINT-MIND.
SPRINT-Senior will be conducted through the existing SPRINT clinical center networks:
- Case Western Reserve University School of Medicine, Cleveland (Principal Investigator: Jackson T. Wright, M.D., Ph.D.)
- Department of Veterans Affairs, VA Medical Center, Memphis (Principal Investigator: William C. Cushman, M.D.)
- University of Alabama at Birmingham (Principal Investigator: Suzanne Oparil, M.D.)
- University of Utah, Salt Lake City (Principal Investigator: Alfred K. Cheung, M.D.)
- Wake Forest University Baptist Medical Center, Winston-Salem, N.C. (Principal Investigator: David C. Goff, Jr., M.D., Ph.D.)
- The coordinating center for the study is Wake Forest Baptist (Principal Investigator: David Reboussin, Ph.D.).