By Martin S. Lipsky, MD
Adjunct Professor, Institute on Aging, School of Community Health, Portland State University; Dean Emeritus, University of Illinois College of Medicine, Rockford
Dr. Lipsky is a retained consultant for Health Solutions & Strategies.
SYNOPSIS: Designed to see if lower blood pressures reduced the risk of blood pressure-related health outcomes, the NIH ended the SPRINT trial early and issued a news release that a lower blood pressure target significantly reduces cardiovascular complications in adults age 50 and older with high blood pressure.
SOURCE: Landmark NIH study shows intensive blood pressure management may save lives. Available at: http://www.nih.gov/news/health/sep2015/nhlbi-11.htm. Accessed Oct. 1, 2015.
The residual risk of middle aged and elderly individuals experiencing high blood pressure is about 90%, and the lifetime probability of receiving antihypertensive medication is 60%.1 Since high blood pressure is a risk factor for many common causes of morbidity and mortality, including coronary artery disease, stroke, heart failure, kidney disease, and cognitive decline, optimizing treatment is an important public health issue. Although clinicians commonly target treating blood pressure to levels < 140/90 mmHg, observational studies show a progressive increase in risk with blood pressures above 115/75. However, the optimal blood pressure target to reduce adverse outcomes is unclear, and the benefit of reduction below a systolic pressure of 140 mmHg has not been proven in a larger trial.
The Systolic Blood Pressure Intervention Trial (SPRINT)2 was designed to compare two strategies for treating systolic blood pressure: one with the standard target of < 140 mmHg and the other aimed at the more intensive target of < 120 mmHg. Enrollment criteria included: age ≥ 50 years with an average baseline systolic blood pressure ≥ 130 mmHg and evidence of cardiovascular disease, chronic kidney disease, increased cardiovascular disease risk (> 15% over 10 years or age ≥ 75 years). Primary outcomes included myocardial infarction, acute coronary syndrome, stroke, heart failure, or cardiovascular disease death. Secondary outcomes included all-cause mortality, decline in kidney function or development of end-stage renal disease, incidence of dementia, decline in cognitive function, and small-vessel cerebral ischemic disease.2
Beginning in 2009, the SPRINT study recruited more than 9300 participants from approximately 100 medical centers and clinical practices. To date, SPRINT is the largest study to explore targeting treatment to blood pressure levels below well-established clinical guidelines, recommending a systolic blood pressure of < 140 mmHg for healthy adults and < 130 mmHg for adults with kidney disease or diabetes. The standard group received on average two different blood pressure mediations, while the intensive treatment group received an average of three medications.2
On Sept. 11, 2015, the NIH stopped the SPRINT trial early based on the initial results indicating that treating to lower blood pressure significantly lowered the risk of cardiovascular death in adults ≥ age 50 years of age with high blood pressure.3 According to Gary Gibbons, MD, director of the National Heart Lung and Blood Institute (NHBLI), “This study provides potentially lifesaving information that will be useful to healthcare providers as they consider the best treatment options for some of their patients, particularly those over the age of 50.” He also indicated that the NHBLI looks forward to quickly publishing the results to help inform patient care and to incorporate into the future development of evidence-based clinical guidelines.3
COMMENTARY
The SPRINT release made the bold assertion that intensive intervention targeting a blood pressure of < 120 mmHg reduced the rate of heart attacks and stroke by about one-third and cardiovascular deaths by about 25%. However, the NIH did not release the study details at the time of their announcement, indicating that the full paper would be published soon in an as-yet-to-be-named journal.
Current Eighth Joint National Committee guidelines recommend that drug treatment be initiated in healthy people > 60 years of age when the blood pressure is 150/90 or higher. Medications should be introduced in adults < 60 years of age who have persistent blood pressure readings of > 140/90. Findings from the SPRINT could significantly alter this recommendation. However, the release is already coming under criticism for failing to provide an opportunity to review the study details. For example, the issue of side effects, dropout rate, and other key factors suggest a need for caution until the full publication is released and the medical community can digest the findings.5 Others also question whether the study over emphasizes drug treatment while neglecting lifestyle measures.
In some ways, the SPRINT findings make sense and match the observation that those with lower blood pressure experience a lower risk of blood pressure-associated complications. I was taught that as long as patients felt well, having a low blood pressure was good. However, at the same time, I think about how often I saw patients experience dizziness and other troublesome side effects from blood pressure medicines. Also, in contrast to the SPRINT findings, the Cochrane database reports that antihypertensive treatment for mild hypertension may not reduce morbidity or mortality and is associated with a high dropout rate because of adverse effects.6 Although the SPRINT findings suggest benefit from more aggressive treatment, until the full report is published and discussed, caution is probably the wisest course approach before subjecting patients to the cost and risks of more aggressive treatment. On the other hand, in individuals doing well and whose blood pressure is < 140/90 on treatment, continuing existing treatment rather than reducing dosage or dropping a drug might be worthwhile.
REFERENCES
- Vasan RS, et al. Residual lifetime risk for developing hypertension in middle-aged woman and men. JAMA 2002;287:1003-1010.
- Ambrosius WT, et al. SPRINT Study Research Group. The design and rationale of a multicenter clinical trial comparing two strategies for control of systolic blood pressure: The Systolic Blood Pressure Intervention Trial (SPRINT). Clin Trials 2014 Oct;11:532-546.
- National Heart, Lung, and Blood Institute. Landmark NIH study shows intensive blood pressure management may save lives. Available at: http://www.nhlbi.nih.gov/news/press-releases/2015/landmark-nih-study-shows-intensive-blood-pressure-management-may-save-lives. Accessed Sept. 25, 2015.
- James PA, et al. 2014 Evidence-based guideline for the management of high blood pressure in adults report from the panel members appointed to the Eighth Joint National Committee (JNC 8). JAMA 2014;311:507-520.
- NIH SPRINT study sparks questions about overtreatment of mild hypertension. Available at: http://www.healthnewsreview.org/2015/09/nih-sprint-study-sparks-questions-about-overtreatment-of-mild-hypertension/.
- Diao D, et al. Pharmacotherapy for mild hypertension. Cochrane Database Syst Rev 2012;8:CD006742.
