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How Low Can You Go?

Implications of the Systolic Blood Pressure Intervention Trial for Hypertension Management

Dennison Himmelfarb, Cheryl R. RN, ANP, PhD, FAHA, FPCNA, FAAN; Hayman, Laura L.; Worel, Jane Nelson

Journal of Cardiovascular Nursing: March/April 2016 - Volume 31 - Issue 2 - p 99–100
doi: 10.1097/JCN.0000000000000323
DEPARTMENTS: Progress in Prevention
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Cheryl R. Dennison Himmelfarb, RN, ANP, PhD, FAHA, FPCNA, FAAN Associate Professor, Department of Acute and Chronic Care, School of Nursing, and Division of Health Sciences Informatics, School of Medicine, Johns Hopkins University, Baltimore, Maryland.

Laura L. Hayman, PhD, RN, FAAN, FAHA Associate Vice-Provost for Research and Professor of Nursing, College of Nursing and Health Sciences, University of Massachusetts Boston.

Jane Nelson Worel, MS, RN, APN-BC, FAHA, FPCNA Nurse Practitioner, Phases Primary Care for Women, Madison, Wisconsin.

The authors have no conflicts of interest to disclose.

Correspondence Cheryl R. Dennison Himmelfarb, RN, ANP, PhD, FAHA, FPCNA, FAAN, Division of Health Sciences Informatics, Johns Hopkins School of Nursing, 525 N Wolfe St, Rm 527, Baltimore, MD 21205-2110 (cdennis4@jhu.edu).

About 70 million American adults (29%) have hypertension (HTN)—that is 1 of every 3 adults.1 The prevalence of HTN rises dramatically with increasing age in both men and women, from approximately 10% at 20 to 44 years of age to 75% or higher for those 75 years or older.2 Hypertension increases risk for heart attack, stroke, heart failure, and kidney disease. And, despite our efforts, only about half (52%) of people with HTN have their condition under control.1 More than 360 000 American deaths in 2013—almost 1000 deaths each day—included HTN as a primary or contributing cause.2 National Institutes of Health officials recently announced that the landmark trial Systolic Blood Pressure Intervention Trial (SPRINT) would be stopped early to rapidly release significant results suggesting that intensive blood pressure management may save lives. Given the high prevalence and deleterious impact of uncontrolled HTN, these recent data have many clinicians and patients alike asking “how low can you go” with blood pressure to safely decrease cardiovascular risk and mortality.

In SPRINT, more than 9300 men and women were randomly assigned to 2 systolic blood pressure targets: (1) less than 120 mm Hg, which is lower than any guideline ever suggested, or (2) less than 140 mm Hg.3 The study population was diverse, and women, racial/ethnic minorities, and the elderly were well represented. Participants were required to meet all the following criteria: age of at least 50 years, a systolic blood pressure of 130 to 180 mm Hg, and an increased risk of cardiovascular events (ie, clinical or subclinical cardiovascular disease other than stroke; chronic kidney disease, excluding polycystic kidney disease; a 10-year risk of cardiovascular disease of ≥15% on the basis of the Framingham risk score; or age ≥75 years). Patients with diabetes mellitus or previous stroke were excluded. Participants in both arms received standardized blood pressure measurement and protocol-driven HTN follow-up and treatment intensification, with emphasis placed on using medication classes with the best outcomes in large clinical trials: thiazide-type diuretics, calcium channel blockers, and angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, although other agents, including spironolactone, amiloride, β-blockers, vasodilators, or α-receptor blockers, could be added if necessary. The mean numbers of antihypertensive medications were 2.8 and 1.8 in the intensive treatment and standard treatment groups, respectively.

At 1 year, the mean systolic blood pressure was 121 mm Hg in the intensive treatment group and 136 mm Hg in the standard treatment group. The intervention was stopped early after a median follow-up of 3.26 years owing to a significantly lower rate of the primary composite outcome in the intensive treatment group than in the standard treatment group (1.65% vs 2.19% per year; hazard ratio with intensive treatment, 0.75; 95% confidence interval, 0.64–0.89; P < .001).3 All-cause mortality was also significantly lower in the intensive treatment group (hazard ratio, 0.73; 95% confidence interval, 0.60–0.90; P = .003).3 Importantly, the effects of the intervention on the rate of the primary outcome and on the rate of death from any cause were consistent across the prespecified subgroups, including age, sex, and race. The investigators indicated that on balance, the intensive intervention was well tolerated, although rates of serious adverse events of hypotension, syncope, electrolyte abnormalities, and acute kidney injury or failure, but not of injurious falls, were higher in the intensive treatment group than in the standard-treatment group.3

The strengths of SPRINT include a large sample size, the diversity of the population (including a large proportion of patients ≥75 years old), and its success in achieving the intended separation in systolic blood pressure between the 2 intervention groups throughout the trial.3 Although to obtain a more thorough evaluation of the effects of intensive blood pressure lowering on the central nervous system and kidney end points, we await publication of analyses of these important secondary outcomes. The lack of generalizability to populations not included in SPRINT, such as persons with diabetes, previous stroke, and those younger than 50 years of age, is considered a limitation. However, Bress et al4 used National Health and Nutrition Examination Survey data (2007–2012) to estimate that almost 17 million US adults—approximately one quarter of adults with HTN—met SPRINT eligibility criteria; thus, the findings are indeed generalizable to a large population who are at high risk and with great potential to benefit from intensive blood pressure lowering.

The SPRINT findings have important implications for HTN management and will inform upcoming HTN treatment guidelines. It was shown in SPRINT that among adults with HTN but without diabetes, lowering systolic blood pressure to a target goal of less than 120 mm Hg, as compared with the standard goal of less than 140 mm Hg, resulted in significantly reduced rates of cardiovascular events, such as heart attack and heart failure, as well as stroke, by almost a third and the risk of death by almost a quarter. The adverse event rate was higher in the intensive treatment group, although long-term consequences of these adverse effects are unclear and the potential for harm seems to be offset by the positive effects of more intensive treatment.

The task set forth by SPRINT—to achieve a blood pressure target goal of 120 mm Hg, when currently only half of those treated achieve the target of 140 mm Hg—is daunting to say the least.1 High-quality HTN management is multifactorial and requires the engagement of patients, families, providers, and healthcare delivery systems.5 This includes expanding patient and healthcare provider awareness, appropriate lifestyle modifications, access to care, systems support for clinical decision making (ie, treatment algorithms), collaboration, a high level of patient self-management and medication adherence, and adequate follow-up.5,6 A key feature of effective HTN care models is a multidisciplinary team, most often including nurses, that collaborates in the delivery of HTN care services. Team-based HTN care has been demonstrated to increase the proportion of individuals with controlled blood pressure and reduce both systolic and diastolic blood pressure.6 Achieving lower blood pressure targets will require an enhanced team approach to HTN care that includes shared decision making with our patients.

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REFERENCES

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2. Mozaffarian D, Benjamin EJ, Go AS, et al. Heart Disease and Stroke Statistics—2015 update: a report from the American Heart Association. Circulation. 2015; 131(4): e29–e322.
3. SPRINT Research Group A randomized trial of intensive versus standard blood pressure control. N Engl J Med. 2015; 373(22): 2103–2016.
4. Bress AP, Tanner RM, Hess R, Colantonio LD, Shimbo D, Muntner P. Generalizability of results from the Systolic Blood Pressure Intervention Trial (SPRINT) to the US adult population [published online ahead of print October 31, 2015]. J Am Coll Cardiol. 2015. pii:S0735-1097(15)07103-X. doi:10.1016/j.jacc.2015.10.037.
5. Go AS, Bauman MA, Coleman King SM, et al. An effective approach to high blood pressure control: a science advisory from the American Heart Association, the American College of Cardiology, and the Centers for Disease Control and Prevention. Hypertension. 2014; 63(4): 878–885.
6. Proia KK, Thota AB, Njie GJ, et al. Team-based care and improved blood pressure control: a community guide systematic review. Am J Prev Med. 2014; 47(1): 86–99.
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