The SPRINT Trial and Hypertension Treatment
Written by Editor   
Thursday, January 14, 2016 12:00 AM

While hypertension control has benefits the absolute benefits are modest and the SPRINT study may not be the best indicator in a healthy population.

For over a decade a major advance in our understanding of the treatment of hypertension has been awaited.  The SPRINT trial was a randomized controlled trial comparing a systolic blood pressure target of <120 mm Hg versus <140 mm Hg among almost 10,000 patients with systolic hypertension who were over 50 years old (mean age 68) and who had cardiovascular risk factors, without a history of diabetes or stroke.

Patients were seen monthly for the first 3 months of the trial and then every 3 months thereafter, with ongoing adjustment in their anti-hypertensive regimens to achieve the desired blood pressure targets. The primary outcome was a composite of cardiovascular events and death. The methodology was reasonably high quality, though it was an open label study -- which may have introduced some biases, particularly since there was considerable subjectivity in defining some of the outcomes such as whether or not adverse effects were severe.

The trial, funded by the National Institutes of Health, was stopped early after a median of 3.3 years (5 years were planned) when the benefit of the more aggressive blood pressure target became apparent (some have argued this decision was premature, though the findings were certainly clear by the time the trial was stopped).

The authors sum up their findings as follows: "Among patients at high risk for cardiovascular events but without diabetes, targeting a systolic blood pressure of less than 120 mm Hg, as compared with less than 140 mm Hg, resulted in lower rates of fatal and nonfatal major cardiovascular events and death from any cause, although significantly higher rates of some adverse events were observed in the intensive-treatment group."

These new findings tell us that we should be careful to implement these new results thoughtfully.

The absolute benefits of targeting a blood pressure <120 mm Hg, while not trivial, strike us as modest:

  • Rates of myocardial infarction (MI) per year were 0.65% in the intensive therapy group versus 0.78% in the standard therapy group.

  • Rates of stroke per year were 1.3% in the intensive therapy group versus 1.5% in the standard therapy group. 

  • Annual death rates were 1.03% in the intensive therapy group versus 1.40% in the standard therapy group. 

  • The number needed to treat to prevent any of the composite endpoints (MI, acute coronary syndrome, stroke, heart failure, cardiovascular death) was 61 over the 3.3-year study period.

The patients in SPRINT were all at high cardiovascular risk (chronic kidney disease; a 10-year risk of cardiovascular disease of 15% or greater; or an age of 75 years or older). It is likely that the absolute benefits of aggressive blood pressure control are substantially lower among a healthier population and thus it would not be prudent to extrapolate SPRINT's conclusions to all with hypertension.

SPRINT was conducted in an experimental setting in which the participants were carefully selected and received close monitoring -- which might not be practical in regular clinical practice. The adverse effects of intensive therapy -- which included hypotension, syncope, electrolyte abnormalities, and acute kidney injury and occurred at almost double the control rate -- would likely be even greater outside of a study setting.

Furthermore, in busy clinical practice, blood pressure is often measured using less-than-ideal techniques, leading to inaccurately elevated blood pressure readings. Thus, it is important to recognize that accurately measuring and safely achieving systolic blood pressure targets of <120 mm Hg outside of a study setting will require substantial resources.

Finally, and perhaps most importantly, the participants in SPRINT had numerous modifiable lifestyle risk factors: 13% were smokers, and most were overweight or obese. So although patients like those in SPRINT clearly benefit from vigilant pharmacologic management of their hypertension, they also would benefit from aggressive lifestyle interventions, including smoking cessation, exercise, and improved nutrition. It will be critical that these simple therapies are not forgotten as our focus on pharmacologic therapy intensifies.

Most importantly, SPRINT reinforces the notion that appropriate treatment of hypertension -- involving both intensive lifestyle changes and pharmacotherapy -- has tremendous potential to improve health.

Should the SPRINT findings change our approach to treating hypertension? Yes, for high-risk patients like those studied in the trial. For those in whom more aggressive targets seem to make sense aim for systolic targets as low as <120 mm Hg. But when we aim for these more aggressive blood pressure targets, we will be especially mindful to use nonpharmacologic options to lower blood pressure whenever possible, monitor closely for adverse effects, and ensure that blood pressure is measured accurately.

As for the many patients in our practices with hypertension who are younger and healthier than those included in SPRINT, we do not think it is yet appropriate to alter our blood pressure targets. As noted above, the benefits may not apply in these groups.