Hong
Kong Med J 2019 Feb;25(1):64–7 | Epub 3 Jan 2019
© Hong Kong Academy of Medicine. CC BY-NC-ND 4.0
MEDICAL PRACTICE
Update on the Hong Kong Reference Framework for
Hypertension Care for Adults in Primary Care Settings—review of evidence
on the definition of high blood pressure and goal of therapy
MK Lim, MB,BS, FHKAM (Family Medicine)1;
Stanley CN Ha, BSc, MPH1; KH Luk, MB, BS, FHKAM (Family
Medicine)1; WK Yip, MB, ChB, FHKAM (Family Medicine)1; Caroline
SH Tsang, MB, ChB, FHKAM (Community Medicine)1; Martin CS Wong,
MD, FHKAM (Family Medicine)2
1 Primary Care Office, Department of
Health, Hong Kong
2 Advisory Group on Hong Kong Reference
Framework for Care of Diabetes and Hypertension in Primary Care Settings,
Hong Kong
Corresponding author: Dr KH Luk (kam_hung_luk@dh.gov.hk)
![](https://www.hkmj.org/sites/default/files/mjimage/pdficon.png)
Abstract
The Hong Kong Reference Framework for
Hypertension Care for Adults in Primary Care Settings is updated
regularly to ensure it reflects the latest medical development and best
practice. In 2017, guidelines from the United States included a major
change, adopting the lower blood pressure values of 130/80 mm Hg in
defining hypertension, in contrast to the prevailing international
consensus of 140/90 mm Hg. After thorough review of the literature and
international guidelines, the Advisory Group on Hong Kong Reference
Framework for Care of Diabetes and Hypertension in Primary Care Settings
(Advisory Group) recommends that the definition of hypertension adopted
in the Reference Framework should remain unchanged as a blood pressure
of ≥140/90 mm Hg, as there is currently inadequate evidence and lack of
general consensus to support such change in Hong Kong. The Advisory
Group agrees on individualised treatment goals, and recommends that the
initial blood pressure goal for individuals with uncomplicated
hypertension should be <140/90 mm Hg; for those who can tolerate it,
the goal should be ≤130/80 mm Hg. A lower blood pressure is advisable
for young or overweight/obese patients, smokers, and patients with other
cardiovascular risk factors.
Introduction
Hypertension is an important cardiovascular risk
factor and the commonest chronic disease in Hong Kong, with a prevalence
of 27.7% among people aged ≥15 years.1
The Primary Care Office of the Department of Health first published the
Hong Kong Reference Framework for Hypertension Care for Adults in Primary
Care Settings (Reference Framework) in 2010.2
Drawing on international evidence of best practice, the Reference
Framework provides an evidence-based reference to primary healthcare
professionals in the identification and management of hypertension in Hong
Kong. To ensure the Reference Framework reflects latest medical
development and evidence, it is updated regularly with expert advice from
the Advisory Group on Hong Kong Reference Framework for Care of Diabetes
and Hypertension in Primary Care Settings (Advisory Group). The Advisory
Group comprises representatives from academia, relevant Colleges of the
Hong Kong Academy of Medicine, and professional organisations.
In 2017, the American College of Cardiology (ACC)
and the American Heart Association (AHA) released guideline
recommendations using lower blood pressure (BP) values to define
hypertension as systolic BP (SBP) ≥130 mm Hg and/or diastolic BP (DBP) ≥80
mm Hg.3 This recommendation is in
contrast to the prevailing consensus of SBP ≥140 mm Hg and/or DBP ≥90 mm
Hg adopted by the World Health Organization and other international
guidelines.4 The BP goal of
hypertensive therapy was also lowered to <130/80 mm Hg in the new
ACC/AHA guideline.3 It is
foreseeable that these new recommendations would arouse concern regarding
the diagnosis and management of hypertension at individual patient care
level, as well as issues related to disease labelling, changes in
epidemiology, and the applicability of these recommendations to other
populations. Even within the United States, the recommendations in this
guideline were not unanimously agreed with among different authorities,
and the application of these recommendations remains controversial.5 6 There is also
little understanding of how these recommendations translate to non–United
States populations, and there is currently no general consensus on the
adoption of these recommendations in Hong Kong.
The aim of this study was to review the relevant
literature, discuss the benefits and potential harms of setting lower BP
values in the diagnosis and management of hypertension, and suggest
updated recommendations on care for individuals with uncomplicated
hypertension in the context of the primary care settings in Hong Kong.
What does the current evidence say?
Benefits of a lower blood pressure definition and
treatment goal
Hypertension is a well-known modifiable risk factor
for cardiovascular disease. It is associated with a number of adverse
outcomes such as stroke, myocardial infarction, heart failure, peripheral
artery disease, end-stage renal disease, and premature death.7 Meta-analyses of observational prospective studies
suggested that people with SBP 120 to 139 mm Hg and/or DBP 80 to 89 mm Hg
may also be at risk of cardiovascular events.8
9 10
11 12
13 14
15 16
17 For this group of people, it
was observed that the higher the BP was, the higher the cardiovascular
risk was, in general. However, the risk was less significant and less
clearly established in Asians, except for the risk of stroke which was
shown to be lower, similar to, or even higher than that for non-Asians
from different meta-analyses. 8 9 10
11 12
13 14
15 16
17 The benefit of lowering BP to
<140/90 mm Hg is well established. A meta-analysis showed that, when
compared with treatment with a mean BP goal of 140/81 mm Hg, more
intensive treatment with a lower mean BP goal of 133/76 mm Hg provided
additional benefits on reducing the risk of major cardiovascular events,
myocardial infarction, stroke, and albuminuria.18
However, although it was shown that treatment with a BP goal of <140/90
mm Hg lowered cardiovascular risk in general, further reductions in BP may
further reduce the risk only of stroke.19
This relationship between BP values and the risk of stroke is also seen in
the Chinese population. A study involving 17 720 Chinese uncomplicated
hypertensive adults concluded that an SBP goal of 120 to 130 mm Hg
resulted in the lowest risk of first stroke.20
Since the above findings were mostly from
meta-analyses based on observational prospective studies, it may be
worthwhile to have a brief discussion on the SPRINT21 trial and the ACCORD22
trial, which were the two major randomised controlled trials on lower BP
goals. The participant characteristics were different in these two trials;
SPRINT involved hypertensive patients with increased cardiovascular risk
but no history of diabetes mellitus or stroke, whereas ACCORD included
patients with type 2 diabetes mellitus.21
22 Both trials compared the
clinical outcomes and adverse events in an intensive treatment group (SBP
<120 mm Hg) and a standard treatment group (SBP <140 mm Hg). The
results regarding the primary outcome were different in the two trials.
The SPRINT trial concluded that the intensive BP-lowering treatment
significantly lowered rates of heart failure, fatal major cardiovascular
events, and all-cause mortality.21
In contrast, the ACCORD trial failed to demonstrate such cardiovascular
benefits in the intensive treatment group. The ACCORD trial concluded that
intensive BP-lowering treatment did not reduce the rate of the primary
composite outcomes of fatal and non-fatal major cardiovascular events.22
There was concern regarding the use of unattended
automated office BP in the SPRINT trial; automated office BP had not been
used in any previous major randomised controlled trials (such as ACCORD)
on BP-lowering treatment.23 When
compared with conventional office BP measurement, automated office BP may
result in lower BP values due to the absence of the white-coat effect.
Therefore, it has been suggested that the BP values reported in SPRINT may
actually correspond to conventional office SBPs of 130 to 140 mm Hg and
140 to 150 mm Hg in the more intensive and less intensive BP-lowering
treatment groups, respectively.7 It
is unclear if these findings can be extrapolated to hypertensive patients
in Hong Kong.
Potential harm of a lower blood pressure definition and
treatment goal
In both SPRINT and ACCORD trials, significantly
higher rates of adverse events were observed in patients treated with
lower BP goals (ie, the intensive treatment group). In these groups,
patients used a larger average number of antihypertensive medications than
those in the standard treatment group. The recorded adverse events
included hypotension, electrolyte abnormality, and acute kidney injury.21 22
Recent systemic reviews and meta-analyses have proposed that intensive
BP-lowering treatment increases the risk of cardiovascular death without
observable benefits; these studies have concluded that there is
insufficient evidence to justify the lower BP goal.24 25 26 A large retrospective cohort study in Hong Kong,
which involved around 100 000 Chinese patients with diabetes mellitus
receiving primary care services, identified that the SBP range for the
lowest risk of cardiovascular diseases and all-cause mortality was 130 to
134 mm Hg. In addition, a J-curve relationship between SBP and all
outcomes of fatal and non-fatal cardiovascular diseases was observed, and
patients with SBP <125 mm Hg were found to have significantly higher
hazard ratio to all composite outcomes.27
Isolated systolic hypertension—an elevation in SBP
but not DBP—is prevalent in older adults.28
29 Because interventions that
lower SBP also reduce DBP, intensive SBP reduction in patients with
isolated systolic hypertension may also result in lower values of DBP. Low
DBP is associated with increased risk of target-organ hypoperfusion and
cardiovascular events.28 29 30 For
example, most ventricular myocardial perfusion occurs during diastole;
therefore, a lower DBP could potentially lead to myocardial hypoperfusion
and associated damage, especially in individuals with left ventricular
hypertrophy or coronary artery disease.30
It has also been suggested that low DBP is associated with an increase in
all-cause mortality.31
Recommendation
Definition of high blood pressure
The Advisory Group regularly reviews the latest
scientific evidence and recommendations from different professional
organisations. The Advisory Group has noticed that there is currently
inadequate evidence and lack of general consensus to support a change to
the definition of hypertension in Hong Kong. Therefore, the Advisory Group
agreed that the Reference Framework definition of hypertension should
remain unchanged as a BP of ≥140/90 mm Hg.
Goal of therapy for hypertensive patients
Hypertensive patients are known to have a higher
cardiovascular risk if they have other risk factors such as smoking,
obesity, sedentary lifestyle, or elevated lipids or glucose; hence, a
global risk approach should be included in assessing the cardiovascular
risk of an individual patient.32
Although some evidence has suggested that a lower BP may provide greater
benefit for patients with higher cardiovascular risk, there is also an
increased risk of treatment noncompliance and serious adverse events from
treatment if the BP is pushed too low, especially in older patients. It
is, therefore, appropriate to determine the treatment goal on an
individual basis after balancing the benefits and potential harms of
having a lower BP goal in the context of that individual. Taking these
into account, the Advisory Group endorses the approach of setting the BP
goal with the consideration of age, underlying cardiovascular risk
factors, and tolerability to treatment of the individual patient, instead
of a single BP goal for all patients. This approach echoes the
recommendation of recently published international guidelines.7 The Advisory Group recommends that the initial BP goal
of therapy for individuals with uncomplicated hypertension should be
<140/90 mm Hg; and for individuals who can tolerate it, the BP goal
should be ≤130/80 mm Hg. A lower BP is advisable for young or
overweight/obese patients, smokers, and patients with other cardiovascular
risk factors.
Conclusion
Hypertension is an important cardiovascular risk
factor and the commonest chronic disease in Hong Kong. Primary care
physicians play an important role in the early diagnosis, prompt
assessment and proper management of hypertension. The Reference Framework
aims to provide updated evidence-based recommendations to support and
influence the current practice of primary care physicians in Hong Kong,
and to reduce the burden of long-term cardiovascular sequelae for
hypertensive patients.
Author contributions
All authors have contributed to the concept or
design of this study, acquisition of data, analysis or interpretation of
data, drafting of the manuscript, and critical revision for important
intellectual content. All authors had full access to the data, contributed
to the study, approved the final version for publication, and take
responsibility for its accuracy and integrity.
Acknowledgements
We would like to thank the members of the Advisory
Group for their invaluable contributions in the development and update of
the Reference Framework.
Conflicts of interest
As an editor of the journal, MCS Wong was not
involved in the peer review process. All other authors have disclosed no
conflicts of interest.
Funding/support
This research received no specific grant from any
funding agency in the public, commercial, or not-for-profit sectors.
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