Systolic Blood Pressure Intervention Trial could impact medical guidelines for treating hypertension, but questions remain
Newswise, November 10, 2015 — Patients whose blood pressure target was lowered by medications to reach a systolic goal of 120 mmHg had their risk for heart attack and heart failure reduced by 38 percent, and their risk for death lowered by 27 percent.
Aggressive treatment appeared to be as effective for adults age 75 and older as for adults age 50-74, according to results from the Systolic Blood Pressure Intervention Trial (SPRINT) presented at the American Heart Association meeting and published online in the <i>New England Journal of Medicine (NEJM) on Nov. 9, 2015.
Intensive blood pressure management was also associated with an increased risk for each of a group of adverse events categorized as life threatening or requiring prolonged hospitalization or disability, including hypotension, fainting, and kidney abnormalities.
Among these, there was greatest increased risk, 64 percent, for acute kidney injury or acute renal failure, although there was no evidence for permanent kidney damage. Future studies will investigate effects of treatment on kidney disease in more detail.
“The positive results of this trial has taken everyone by surprise, and the strong benefits of treatment seem to outweigh the risks,” says Alfred Cheung, M.D., chief of nephrology & hypertension at University of Utah Health Care, and co-author on the study. He led a network of 17 out of the 102 participating clinical sites in the U.S. and Puerto Rico.
“Before deciding to treat blood pressure aggressively, it may be smarter to wait until additional questions are answered.”
He notes that results are still pending on how intensive treatment might impact dementia, cognition, and kidney disease.
Additionally, nothing is known about long-term effects of sustained treatment, nor cost effectiveness. On average, SPRINT trial participants were followed for just over three years.
In Sept, 2015, the National Institutes of Health announced that the SPRINT trial was stopped one year early due to the marked benefits of lowering systolic blood pressure to 120 mmHg, well below the current guidelines of 140, or 150 for those over age 60.
Now, the details of the study are published in NEJM. The results may have implications for the 79 million Americans and 1 billion adults worldwide with hypertension, or high blood pressure, the leading cause of heart disease and stroke.
Adults age 75 and older could potentially benefit the most from interventions based on positive SPRINT results because this age group carries the burden of hypertension: over 75 percent have the condition.
At the same time, they would be predicted to be most at risk for any potential side effects that are still under investigation, says Mark Supiano, M.D., chief of geriatrics at University of Utah Health Care and director of the VA Salt Lake City Geriatric Research, Education, and Clinical Center.
“If there were a single drug with this kind of beneficial outcome, it would be a billion-dollar drug,” says Supiano. “But we can’t just treat the heart, we need to treat the whole person. We will need to exercise caution when implementing this information.”
SPRINT randomly assigned over 9,300 participants one of two blood pressure targets: less than 120 mmHg or less than 140. Participants were age 50 or older, at increased risk for cardiovascular disease, had an systolic blood pressure of at least 130 mmHg, and did not have diabetes, history of stroke, or kidney disease.
Blood pressure was adjusted with antihypertensive medication over the course of the first year, and participants were monitored for an average of three additional years.
The results from SPRINT differ from previous trials demonstrating that a blood pressure target of 120 mmHg did not significantly reduce risk for death.
Cheung says the difference in outcomes may stem from SPRINT’s large sample size and its unique eligibility requirements, which included an older population and individuals with high risk for cardiovascular disease, and excluded patients with diabetes.
“We saw great health improvements in just three years, but it could be that outcomes will improve even more over the course of 10 years, or 30,” says Cheung.
It remains to be determined whether SPRINT results will influence official medical guidelines for treating hypertension.
The research was supported by the National Heart, Lung, and Blood Institute, National Institute of Diabetes and Digestive and Kidney Diseases, National Institute on Aging, National Institute of Neurological Disorders and Stroke, and the Department of Veterans Affairs
“Principle Results of the Systolic Blood Pressure Intervention Trial (SPRINT)” will be published online in NEJM on Nov. 9