Putting SPRINT in Focus for Primary Care

Hi, everyone. I'm Dr Kenny Lin. I am a family physician at Georgetown University School of Medicine, and I blog at Common Sense Family Doctor.

Two months after the National Institutes of Health announced that the Systolic Blood Pressure Intervention Trial (SPRINT)^[1] randomized trial evaluating a lower systolic blood pressure goal for adults at high cardiovascular risk had been stopped early due to unequivocal benefits in the intervention group, the study investigators published their results in the New England Journal of Medicine. Already, there have been calls from many experts to revise the Eighth Joint National Committee (JNC 8) guidelines^[2] for hypertension treatment, which are less than 2 years old.

Family physicians would be forgiven for feeling somewhat bewildered at the back-and-forth of hypertension treatment recommendations over the past several years. Are lower goals really better, and how low is too low? JNC 7,^[3] released in 2003, advised a treatment threshold of 140/90 mm Hg for most adults but included a lower target of 130/80 mm Hg for patients with diabetes or chronic kidney disease and also created the new category of "prehypertension" for healthy persons with blood pressures above 120/80 mm Hg. The lower targets were based on observational studies and expert consensus that treating to these would improve cardiovascular outcomes.

The JNC 8 guideline took a different approach by relying primarily on evidence from randomized controlled trials. They only found strong evidence for treating to a BP of 150/90 mm Hg in adults aged 60 years or older and eliminated the lower targets for patients with diabetes and chronic kidney disease, making the goal 140/90 mm Hg for most people.

My Medscape colleague, Dr John Mandrola, wrote a great summary of SPRINT's major findings: Over a little more than 3 years of follow-up, 61 people needed to be treated to a systolic blood pressure goal of 120 to prevent one cardiovascular event or stroke, and 83 needed to be treated to prevent one death from all causes. On the flip side, more intensive treatment—three blood pressure drugs on average compared with two in the control group—was associated with one additional episode of severe hypotension, one case of syncope, and two more episodes of acute kidney injury for every 100 participants. One interesting finding is that less than half of the excess deaths in the control group were due to cardiovascular causes, which suggests to me that some of the positive effect of the intervention may have been due to doctors paying more attention to patients in the intensive treatment group rather than a direct effect of lower blood pressure.

It's worth noting that the SPRINT results do not completely upend JNC 8. SPRINT focused on an especially high-risk population of adults with hypertension who were aged 50 years or older and had an average Framingham risk score of 20%. Patients with diabetes or a history of a stroke were not included. According to a companion study^[4] published in the Journal of the American College of Cardiology, only 1 in 6 US adults currently receiving blood pressure treatment would have been eligible to participate in this trial. Until new treatment guidelines emerge, I think it is premature to extrapolate these findings to the majority of patients at lower cardiovascular risk—and therefore less likely to benefit—but equally vulnerable to the increased adverse effects observed in this study.

Another key point: The way that blood pressures were measured in this study is probably not the way they are measured in your offices. Although best practice guidelines suggest that patients should be seated and at rest for at least 5 minutes before blood pressure is measured, you and I know all too well how rarely this occurs when patients arrive late or we are running behind schedule.

Recognizing that blood pressures obtained in the office are often inaccurate, the US Preventive Services Task Force^[5] and the Community Preventive Services Task Force^[6] recommend confirming office measurements with self-measured blood pressure monitoring before starting or adjusting medications. In order to make this practice possible, and to implement lower blood pressure goals in selected patients without overtreating them, insurers absolutely must cover patients' purchase of validated blood pressure monitors^[7] and pay family physicians for the extra time it takes to make medication adjustments outside of office visits.

This has been Dr Kenny Lin for Medscape Family Medicine. Thank you for listening.

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Cite this: Kenneth W. Lin. Putting SPRINT in Focus for Primary Care - Medscape - Nov 16, 2015.