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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 31, No 6, November/December 2020
AFRICA
291
NT-proBNP and metabolic risk factors in a bi-ethnic
cohort: the Ambulatory Blood Pressure in African
prospective cohort study
Amra Juji
ć
, Olle Melander, Peter M Nilsson, Leoné Malan, Artur Fedorowski, Martin Magnusson
Abstract
Background:
We explored the association of N-terminal pro-
brain natriuretic peptide (NT-proBNP) with metabolic traits
in a bi-ethnic African–Caucasian cohort.
Methods:
Baseline examinations of the Sympathetic activity
and Ambulatory Blood Pressure in African (SABPA) prospec-
tive cohort study were performed between 2008 and 2009, and
re-examination after a three-year follow up in South African
teachers (black African,
n
= 194; Caucasian,
n
= 203).
Results:
Each one standard deviation increment of
NT-proBNP was significantly inversely associated with body
mass index (
β
–1.01), glycated haemoglobin (
β
–0.14 %),
waist circumference (
β
–1.82), HOMA-IR (
β
–0.47), insulin
(
β
–1.66) and triglyceride levels (
β
–0.04). Each one standard
deviation increment of NT-proBNP was also associated with
reduced odds of incident diabetes, and subjects within the
highest quartile of NT-proBNP were at lowest risk (OR: 0.24;
95% CI: 0.06–0.96;
p
= 0.041).
Conclusions:
In the SABPA cohort, Africans and Caucasians
had similar NT-proBNP levels; however, the associations for
Africans were stronger. Those findings suggest that BNP may
affect the propensity for metabolic disturbances differently in
Africans and Caucasians.
Keywords:
Africans, bi-ethnic, Caucasians, metabolic,
NT-proBNP
Submitted 21/1/19, accepted 16/6/20
Published online 11/11/20
Cardiovasc J Afr
2020;
31
: 291–297
www.cvja.co.zaDOI: 10.5830/CVJA-2020-017
Natriuretic peptides (NPs) are widely recognised as potent
vasoactive hormones that play a key role in volume loading and
cardiac remodelling.
1
Their gene transcription and secretion
increase as a result of cardiac stress, for example, stretching of
the cardiac atria or due to ventricular pressure or volume load.
2
Consequently, BNP levels are elevated in conditions such as
heart failure, and BNP are also today extensively used as heart
failure biomarkers in clinical routine.
3
In addition to cardiac
stress, there is also evidence that neurohormonal factors such
as angiotensin II, thyroid hormones, inflammatory cytokines
interleukin (IL)-1, IL-6 and tumour necrosis factor
α
(TNF-
α
)
affect and interact with NP secretion.
4,5
The last two decades of research has also identified NPs
as hormones with significant protective metabolic actions,
and proposed that genetically predisposed low levels of NPs,
the so called ‘natriuretic handicap’, is a cause, rather than a
consequence, of metabolic disorders such as obesity, insulin
resistance and diabetes.
6-9
Although NP secretion is greatly
influenced by volume load on the heart, there is evidence that as
much as 40% of the variation in BNP levels could be explained
by genetic factors.
10,11
Other studies demonstrate that African
Americans have lower NT-proBNP levels than Caucasians.
12-14
However, higher levels independent of diabetes status were
observed in an African cohort compared to Caucasian
counterparts.
15
In this study, we aimed to explore the associations of
NT-proBNP with obesity, hypertriglyceridaemia, the metabolic
syndrome, insulin resistance and diabetes in an African versus a
Caucasian gender-matched cohort from South Africa.
Methods
This study is part of the Sympathetic activity and Ambulatory
Blood Pressure in Africans (SABPA) study of 409 African and
Caucasian school teachers (aged 20–62 years), working in the
North-West Province, South-Africa.
16
The examination was
conducted in 2008 and 2009 and repeated in 2011 and 2012
(mean follow-up time three years), with an 87.8% successful
follow-up rate (Fig. 1).
The study sample was selected to ensure homogeneity
regarding socio-economic status and working environment.
Exclusion criteria for the SABPA study were: the use of alpha-
or beta-blockers, use of psychotropic substances, tympanum
Department of Clinical Sciences, Skane University
Hospital, Lund University, Malmö, Sweden
Amra Juji
ć
, PhD,
amra.jujic@med.lu.seOlle Melander, MD, PhD
Peter M Nilsson, MD, PhD
Artur Fedorowski, MD, PhD
Martin Magnusson, MD, PhD
Centre of Emergency Medicine, Skane University Hospital,
Malmö, Sweden
Olle Melander, MD, PhD
Hypertension in Africa Research Team (HART), North-West
University, Potchefstroom Campus, South Africa
Leoné Malan, PhD
Martin Magnusson, MD, PhD
Department of Cardiology, Skane University Hospital, Lund
University, Malmö, Sweden
Amra Juji
ć
, PhD
Artur Fedorowski, MD, PhD
Martin Magnusson, MD, PhD
Wallenberg Centre for Molecular Medicine, Lund
University, Malmö, Sweden
Martin Magnusson, MD, PhD