Is It Time to Reappraise Blood Pressure Thresholds and Targets?
A Statement From the International Society of Hypertension—A Global Perspective
The SPRINT (Systolic Blood Pressure Intervention Trial) findings,1 together with the publication of other major studies within the last year addressing how low blood pressure should be targeted to prevent cardiovascular events in patients with hypertension,2–4 support what we have known for a long time that: (1) blood pressure >115/75 mm Hg is associated with increased risk of cardiovascular disease and stroke, (2) blood pressure lowering is associated with reduced morbidity and mortality, (3) antihypertensive drugs reduce the incidence of hypertension-associated events, and (4) prevention of cardiovascular morbidity is largely related to blood pressure lowering per se, although other effects of the drugs used contribute to this benefit.
The questions that are now posed, particularly in response to an editorial commentary by the Editors of this Journal,5 are the following: What is the threshold at which antihypertensive treatment should be initiated? and what target blood pressure should we strive for to achieve maximum benefit in patients with hypertension? SPRINT and other recent meta-analyses and trials provide new data that allow us to sharpen and refine recommendations for blood pressure targets in people with hypertension.1–4 Here, we will briefly address the questions in the worldwide context of hypertension.
In hypertensive patients without diabetes mellitus, previous stroke or polycystic kidney disease, SPRINT has provided strong evidence that targeting systolic blood pressure of <120 mm Hg (as measured by an automated measurement protocol in the office)1 provides significantly stronger protection from cardiovascular events and death than the traditionally accepted target of <140 mm Hg. This study was conducted in a hypertensive patient cohort of intermediate-to-high cardiovascular risk. It should be highlighted that the target of 120 mm Hg in SPRINT was based on blood pressure readings using a defined protocol with an office automated device, where blood pressure was measured 3× in the absence of clinical personnel.1 On the basis of the known differences between readings obtained by automated devices and conventional measurements,6 this average would translate to higher readings (130 mm Hg) in clinical practice. Hence, if the goal were to reduce blood pressure to <120 mm Hg using conventional methods, there is a risk that blood pressures would in fact be lower than SPRINT’s 120 mm Hg, with unknown consequences, as highlighted in a recent editorial.7 Accordingly, it is critical that the SPRINT findings are interpreted in the context of the protocol that was used to measure blood pressure.
Moreover, although SPRINT aimed for <120 mm Hg, it should be emphasized that the study did not actually achieve its target <120 mm Hg, with the intensively treated group having an overall systolic blood pressure of ≈122 mm Hg as recorded by the defined measurement protocol.1 Hence, considering the method used to measure the blood pressure, it may be more appropriate to conclude that SPRINT’s benefits were evident at conventional levels closer to 130 mm Hg, in line with other recent reports from individual trials and meta-analyses, which support a target of <130 mm Hg.2–4,8
Importantly, the SPRINT findings do not exclude any particular patient subgroups, except diabetes mellitus and previous stroke. Indeed, black patients benefited equally as well as white, and the results in older patients (≥75 years) were at least as good as in the younger group. However, for patients aged >80 years, in whom safety data at this low blood pressure are still limited, it would be prudent to follow a cautious path in approaching the <130 mm Hg target.9 Regarding the safety concerns, mainly reductions in renal function, electrolyte abnormalities, and hypotensive symptoms, SPRINT suggests that the benefits of intensive management outweigh adverse outcomes for patients at heightened risk of events.
It should be acknowledged, based on HOPE 3 (Heart Outcomes Prevention Evaluation 3),10 that there is some uncertainty about whether there is sufficient evidence to support the initiation of antihypertensive treatment in patients with systolic blood pressures of <140 mm Hg, particularly if other major cardiovascular risk factors are not present. It should be noted, however, that HOPE 3 did not test differing blood pressure targets.
Because SPRINT excluded hypertensive patients with a history of diabetes mellitus or stroke, considerations for blood pressure targets in patients with diabetes mellitus need to be considered from data in other trials. For diabetic patients, the ACCORD trial (Action to Control Cardiovascular Risk in Diabetes),11 supported by some but not all studies and meta-analyses, seems to suggest a systolic treatment target of <140 mm Hg is sufficient. The one caveat is stroke: in ACCORD and at least one other trial, stroke seemed to be best prevented at <120 mm Hg. But to further complicate decision-making, meta-analysis and individual trials suggest the possibility of increasing some fatal and nonfatal cardiovascular outcomes as well as adverse renal effects, if the pressure is reduced to <130 mm Hg or <120 mm Hg in patients with diabetes mellitus.12–14 Even so, given the serious and justifiably feared consequences of stroke and the inconsistency of the currently available evidence, clinicians should consider discussing the selection of treatment targets with their patients. Meanwhile, reaching a target of 130 mm Hg seems an acceptable compromise.
A Global Perspective by the International Society of Hypertension
The International Society of Hypertension has a strong commitment to and interest in the work of preventing, identifying, and treating hypertensive patients throughout the world. We recognize that recommendations made for more prosperous nations cannot fully apply to all communities or to low and middle income countries. Indeed, hypertension diagnosis and management are often hampered by such fundamental problems due to the lack of blood pressure measuring devices, shortage of personnel trained to measure blood pressures, or to advise patients and initiate therapy. Basic laboratory procedures to check for concomitant conditions, such as diabetes mellitus or lipid disorders, may not be available. Moreover, although most modern antihypertensive agents are now produced in inexpensive generic formulations, their cost and availability still limit treatment in many parts of the world.
In 2014, in collaboration with the American Society of Hypertension, International Society of Hypertension published Guidelines on the Treatment of Hypertension in the Community.15 Although those guidelines recommended a systolic blood pressure of 140 mm Hg as the usual hypertension threshold, they recognized that in several parts of the world, this could put an excessive burden on limited budgets. So, it was suggested for patients without other risk factors, and with systolic blood pressures <160 mm Hg, that initial treatment could be based on lifestyle modifications alone. But even this suggestion, although well intended, could not address the reality that resources to identify additional risk factors in hypertensive patients are often lacking in low-income areas and that, in any case, lifestyle modifications that require dietary adjustments, other than moderation of salt intake, are often unavailable or unaffordable. These challenges may be further compounded by insufficient or ineffective education of healthcare providers, policy makers, and the population.
The findings from SPRINT and the other new reports of the benefits of aggressive therapy emphasize that many underserved hypertensive patients are now even more remote from optimal care. This could be a compelling concern in Africa given the strong benefits achieved by the black patients in SPRINT. In African and many other developing countries, overcrowded clinics are dealing mostly with infectious diseases. We, therefore, anticipate that the wide publicity given by SPRINT and other new high-impact reports will help bring a sense of urgency to resolving this major public health issue, which has more wide-ranging environmental challenges beyond aggressive antihypertensive therapy alone.
Taking into consideration the global target population of interest to the International Society of Hypertension, together with evidence derived from SPRINT and other recent meta-analyses and clinical trials, the practical message from the International Society of Hypertension is to strive for a systolic blood pressure target of 130 mm Hg in most patients with hypertension. This is especially important considering that blood pressure measurements in the community are not likely to be performed using the SPRINT protocol. So, advocating a target of <120 mm Hg is not justified in clinical practice, and in any case would incur the costs of increased clinic visits, more intensive health care, and more medications. In regions of low resources, this added financial and logistical burden is not tenable. Accordingly, although we recognize that there might be benefits in targeting treatment to below our recommended level of 130 mm Hg in nondiabetic hypertensive patients at high cardiovascular risk (as in the SPRINT population), the International Society of Hypertension thinks it is premature to advocate such low targets at a global level.
Sources of Funding
R.M. Touyz is supported through a Chair from the British Heart Foundation (CH/12/4/29762). E.L. Schiffrin is supported by a Canada Research Chair (CRC) on Hypertension and Vascular Research by the CRC Government of Canada/Canadian Institutes of Health Research Program. A.E. Schutte is supported by the South African Medical Research Council and a South African Research Chair (SARChI) by the National Research Foundation.
The opinions expressed in this editorial are not necessarily those of the editors or of the American Heart Association.
This article was sent to Daniel W. Jones, Guest Editor, for review by expert referees, editorial decision, and final disposition.
- © 2016 American Heart Association, Inc.
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