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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 31, No 6, November/December 2020
326
AFRICA
treatment intensification; clarifying the roles of healthcare
providers; and reducing barriers for patients to receive and
adhere to treatment and implement lifestyle modifications.
The impact of well-structured hypertension guidelines is
typically illustrated by data derived from Lackland
et al.
,
14
which showed that the decline in US population stroke mortality
rates coincided with the reduction of population BP, which was
consistent with the lowered BP thresholds and targets described
in the sequential recommendations from the guidelines. PASCAR
identified the creation or adoption of simple and practical
clinical evidence-based hypertension management guidelines
as one of its 10-point action plan to achieve 25% control of
hypertension in Africa by 2025.
11
Summary of key proposals of the ISH global
hypertension guideline and relevance to SSA
Essential versus optimal treatment
The major difference between the ISH global guidelines and
other international guidelines is the stratified recommendations
to accommodate differences in available resources between
countries and within countries. This is a key and novel proposal
in the new ISH guidelines. There is the separation of optimal
versus essential criteria for diagnosis and treatment according to
resource availability in LMICs versus HICs. Even within HICs
there are areas with low-resource settings and vice versa.
Optimal care refers to evidence-based standard of care
articulated in recent major guidelines (ESH/ESC, ACC/AHA)
but it is recognised that implementation of these standards is not
always possible in LMICs. Essential standards refer to minimum
standards of care for low-resourced settings. However, there was
a paucity of evidence supporting this approach and the guideline
committee applied expert opinion. The provision of these
recommendations is based on the need to develop guidelines that
are applicable to all areas of the globe rather than developing
country-specific guidelines. This approach makes it possible to
develop truly international hypertension guidelines.
However, the committee recognises that it may not be feasible
for even the minimum standards to be implemented in many
poorer countries in SSA due to lack of health professionals,
infrastructure, equipment (ECG and BP machines for example)
and finances. No guidance is provided for treating patients under
these circumstances. However, it is suggested that the guidelines
provide a framework for countries to strive for. Perhaps what
is significantly lacking in the essential or minimum standards
is their application to non-physician healthcare workers that
are critical in providing care to the burgeoning numbers of
hypertensive patients in poorer countries in SSA.
This review is not exhaustive and will focus on the essential
recommendations of the ISH hypertension guideline and their
relevance to SSA.
Definition of hypertension, BP measurement and
target BP
The ISH guidelines maintained the traditional definition of
hypertension at a level ≥ 140/90 mmHg and have not aligned
themselves with ACC/AHA guidelines at ≥ 130/80 mmHg. In
SSA more than 90% of hypertensives are not controlled because
of lack of awareness (largely attributable to lack of screening),
failure to access treatment or persistence with treatment use, and
failure of monitoring to ensure control.
15
By redefining hypertension to a level of 130/80 mmHg, this
will significantly increase the prevalence of hypertension. In
the US it was estimated that the number of hypertensives will
increase by 43% or 31.1 million people, and a similar increase
would be expected in SSA, placing an unsustainable additional
burden on health facilities.
16
This, in the light of the lack of
beneficial evidence for initiating treatment in patients at this
lower threshold, does not support these diagnostic criteria for
hypertension in SSA.
One weakness of the ISH guidelines is limiting the definition
of hypertension into two grades (Table 1), excluding grade 3
hypertension: ≥ 180/110 mmHg. In SSA, grade 3 hypertension
is common
17
and usually asymptomatic, but few present with
features of hypertensive emergency. This grade of hypertension
alerts the healthcare worker to a category of hypertension with a
very high risk of adverse outcomes in a short time.
The guidelines make important recommendations regarding
the essential requirements for measurement of BP. This has
to be done on three separate occasions within a four-week
period. Perhaps not completely recognised by the ISH guideline
is the limited availability of functioning BP devices and the
long distances patients may need to travel to have repeated
measurements to establish the diagnosis. While it is ideal to
have the BP repeated at different visits, high-risk patients with
limited access should be treated based on a single set of readings,
possibly if it is > 160/100 mmHg, but especially if > 180/110
mmHg. Similarly, repeated measurements at one clinic visit may
enable a diagnosis to be made based on a single visit.
There are slight differences in BP re-evaluation: in those with
high-normal BP, the BP should be checked in three years, unless
the individual has a higher risk, in which case the BP should be
checked in one year. If normal, the ESH/ESC recommends a BP
review in five years. However, in SSA it may be more appropriate
to make this recommendation three years, due to the high risk
of complications.
However, home and 24-hour ambulatory BP monitoring
are seen as essential for the diagnosis of hypertension. In the
opinion of PASCAR, the latter represents optimal requirement.
Even in a LMIC in SSA, such as South Africa, availability of
24-hour and home BP monitoring in the public sector that
serves over 80% of the population is extremely limited. There
is increasing availability of home-based monitoring devices,
however validation of these devices is sub-optimal and needs to
be improved. Furthermore, there needs to be training in the use
of these devices, both for the patient and home-based carers.
The essential target BP recommended for all hypertensives
is < 140/90 mmHg or a 20/10-mmHg reduction in BP by three
months. For optimal treatment, it is < 130/80 mmHg if tolerated
and not < 120/70 mmHg. In those 65 years old and above or
Table 1. Proposed SSA classification of hypertension,
using office blood pressure measurements
Normal
BP High-normal
Grade 1
hypertension
Grade 2
hypertension
Grade 3
hypertension
SBP* < 130
130–139
140–159
160–179
> 180
DBP* < 85
85–89
90–99
100–109
> 110
BP, blood pressure; SBP systolic BP; DBP, diastolic BP.
*Classification based on the presence of either or both SBP and DBP.