By Beverly Green, MD, MPH, associate investigator at Group Health Research Institute and Group Health Physician.
I’ve done research on high blood pressure (BP) and cared for many patients who have it. Yet right now, if my patients with high BP ask what their BP should be, I can't give them a definite answer. Guidelines don't agree, especially for systolic BP, which is the first number of a BP reading. In fact, the target for BP is very controversial. We know that high BP is a risk factor for heart attacks and strokes and lowering BP decreases this risk. However, especially for older people, lowering BP too much might result in falls, fainting, or cognitive problems.
Based on these concerns, in 2013 an expert panel (the Eighth Joint National Committee) raised the target systolic BP to 150 mm Hg for people older than 60, which differs from American Heart Association guidelines of 140 or lower. Some experts were not happy about the guideline change and worried it would increase strokes, while other experts noted that we don't have evidence on this topic. Thanks to the new SPRINT (Systolic Blood Pressure Intervention Trial) study, we might now have some evidence.
SPRINT compared the systolic BP targets of 140 vs. 120 or less, asking which target leads to fewer strokes and heart attacks and death from these events. Sprint participants were aged 50 or more and either had heart or renal disease or were at risk for these conditions; participants also had a systolic BP of 130 or higher. At least one-third were older than 70. Everyone was given the same BP-lowering medications, but people randomized to the lower target got higher doses or added medications to reach their target. The National Heart, Lung, and Blood Institute (NHLBI) recently ended the SPRINT study more than a year early.
SPRINT seems to suggest that lower BP might be better for reducing heart attacks and strokes.
Researchers end studies early only in unusual circumstances. For SPRINT, this decision and national press statements by Dr. Gary Gibbons, NHLBI director, strongly suggest that the lower BP target of 120 was more effective than the BP target of 140 in preventing cardiac events and deaths. Based on statements by Dr. Gibbons, the lower BP target group does not appear to have had problems such as falling. The full results will be published in a few months and we'll need to examine them closely. So far, though, SPRINT seems to suggest that lower BP might be better for reducing heart attacks and strokes.
However, a target of 120 is much lower than 150! Patients and doctors need to see the actual study results before any changes in care are made. If lower targets are recommended, I'll help my patients with hypertension work toward these BP goals, to give them the best chance of aging well without heart attacks or strokes. But particularly for older patients, we’ll need to monitor carefully for signs of problems with the medications or risks of serious side effects.
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