A thesis submitted to the Faculty of Health Sciences,
University of the Witwatersrand, Johannesburg
in fulfilment of the requirements for the degree of
Doctor of Philosophy
Johannesburg 2016 / Introduction: The African continent, particularly sub-Saharan Africa, is facing a high burden of
disease from the human immunodeficiency virus (HIV) pandemic and nutritional deficiencies, while
at the same time, facing ever increasing rates of cardiovascular diseases (CVDs). The mortality rates
from CVD are almost equal to the death rates from communicable diseases. In Sub-Saharan
countries CVD prevention and management faces many barriers. One such difficulty is the shortage
of data for the descriptive epidemiology of CVD risk factors. In an attempt to address this shortage
of data, we established the Heart of Soweto (HOS) study in one of the largest African urban
communities in South Africa. The purpose of this study was to identify and describe some of the
factors contributing to the emergence of chronic diseases of lifestyle, such as heart disease, high
blood pressure, diabetes and obesity in a black urban African population, within the framework of
the HOS study. We also investigated the impact of a dietary intervention on cardiac function in
subjects with chronic heart failure (CHF) in this black urban cohort.
Methods: Data was collected as part of the “Heart of Soweto” (HOS) study, which was a
prospectively designed registry that recorded data relating to the presentation, investigation and
treatment of patients with newly diagnosed cardiovascular disease presenting to Chris Hani
Baragwanath Hospital (CHBH), Soweto in 2006. Data collected included socio-demographic profile
and all major cardiovascular diagnoses. Heart disease was defined as non-communicable (ND) e.g.
coronary artery disease or communicable (CD) e.g. rheumatic heart disease. A survey was also
conducted on consecutive patients attending two pre-selected primary care clinics in Soweto (644
and 667 patients from the Mandela Sisulu and Michael Maponya clinics, respectively). Data
collected included, ethnicity, duration of residence in Soweto, highest level of education and
employment status. Clinical data collected included prior or current diagnoses of diabetes and
hypertension and pharmacological therapy related to the treatment of hypertension, as well as
smoking status and exposure to second-hand smoking. Weight, height, and waist and hip
circumference were measured. Questions were asked regarding the duration of night-time sleep and
napping during the day. Descriptive studies were undertaken at the Heart Failure Clinic at CHBH,
Soweto to firstly describe the food choices and macro-and micronutrients intake of 50 consecutive
patients presenting with heart failure using an interviewer-administered quantitative food frequency
questionnaire (QFFQ). Food data were translated into nutrient data using the Medical Research
Council (MRC) Food Finder 3, 2007, which is based on South African food composition tables.
Secondly we performed a randomized controlled study of a multidisciplinary, community-based,
chronic HF management program in Soweto, compared with usual care, at CHBH Heart Failure
Clinic located at the Soweto Cardiovascular Research Unit (SOCRU), or at the General Cardiac
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Clinic (standard care) in Soweto. In this study 49 consenting, eligible patients were individually
randomized on a 1:1 basis to either usual care or to the study intervention and cardiac function was
measured before and after the intervention.
Results: Data collected at Chris Hani Baragwanath hospital (CHBH) cardiology clinic from 5328
suspected cases of heart disease, demonstrated that the most prevalent form of heart disease was
hypertensive heart failure (22.0%). It was found that those participants who presented with ND
(35.0%) were older and had higher BMI and mean systolic blood pressure (SBP) and diastolic blood
pressure (DBP) than those with CD (39.0%; all comparisons p<0.001). Within this cohort of 5328 de
novo cases of heart disease, 2505 (47%) were diagnosed with HF, of which 697 (28%) were
diagnosed with r i g h t h e a r t f a i l u r e ( RHF). There were more women than men diagnosed
with RHF (379 vs. 318 cases), and on an adjusted basis, compared with the remainder of the
Heart of Soweto cohort (n = 4631), RHF cases were more likely to be African (adjusted OR
2.33, 95% CI 1.59 – 3.41), with a history of smoking (OR 1.72, 95% CI 1.42 – 2.10), a lower
body mass index (OR 0.96, 95% CI 0.94 – 0.97 per kg/m2) and were less likely to have a family
history of heart disease (OR 0.79, 95% CI 0.64 – 0.96).
Data collected at 2 primary health care clinics in Soweto from 862 women (mean age 41 ± 16 years
and mean BMI 29.9 ± 9.2 kg/m2) and 449 men (38 ± 14 years and 24.8 ± 8.3 kg/m2) indicated that in
females, former smokers had a higher BMI (p<0.001) than current smokers, while exposure to
second hand smoking was associated with a lower BMI (p<0.001) in both genders. Longer sleep
duration in females was associated with a lower BMI (p=0.01). Napping during the day for > 30
minutes in males was related to a lower BMI and waist circumference (β=-0.03, p<0.05 for both) and
lower systolic (β=-0.02, p<0.05) and diastolic BP (β=-0.02, p<0.05). Longer night time sleep
duration was associated with lower diastolic (β=0.004, p<0.01) and systolic BP (β=0.003, p<0.05) in
females. Within this same cohort, o b e s i t y w a s m o r e p r e v a l e n t i n f e m a l e s
( 4 1 . 8 % ) t h a n m a l e s ( 1 4 . 1 % ; p < 0 . 0 0 1 ) , 16% (n = 205) had an abnormal 12-
lead ECG with more men than women showing a major abnormality (24% vs. 11%;
OR 2.63, 95% CI 1.89–3.46). Of 99 cases (7.6%) subject to advanced cardiologic
assessment, 29 (2.2%) had newly diagnosed heart disease which included hypertensive
heart failure (13 women vs. 2 men, OR 4.51 95% CI 1.00–21.2), coronary artery
disease (n = 3), valve disease (n = 3), dilated cardiomyopathy (n = 3) and 2 cases
of acute myocarditis.
Nutritional deficiencies were observed in a cohort presenting with HF at the cardiology outpatient
clinic, CHBH. In women, food choices likely to negatively impact on heart health included added
sugar [consumed by 75%: median daily intake (interquartile range) 16 g (10–20)], sweet drinks
[54%: 310 ml (85–400)] and salted snacks [61%: 15 g (2–17)]. Corresponding figures for men
were added sugar [74%: 15 g (10–15)], sweet drinks [65%: 439 ml (71–670)] and salted snacks
[74%: 15 g (4–22)]. The women’s intake of calcium, vitamin C and vitamin E was only 66%, 37%
and 40% of the age-specific requirement, respectively. For men, equivalent figures were 66%, 87%
and 67%, respectively. Mean sodium intake was 2 372 g/day for men and 1 972 g/day for women,
470 and 294% respectively, of daily recommended intakes (DRI). In men, vitamin C intake was 71 ±
90 (79% of DRI). Similarly, in women vitamin C intake was 66 ± 80 (88% of DRI).
Data collected from our HF management programme study supported the deficient intake of vitamin
C in African subjects presenting with heart failure. Thus, plasma vitamin C concentrations (normal
range 23 – 85 μmol/L) were markedly deficient in both standard care [6.53 (3.80, 9.22) μmol/L] and
managed care [3.65 (1.75, 8.23) μmol/L] groups. In terms of clinical presentation, males were
significantly older (49.9 ± 10.9 years; p<0.005) than females (37.2 ± 12.8) and at follow-up females
had a significantly higher ejection fraction (34.8 ± 9.56 %) than males (29.5 ± 8.27; p<0.05) and
when the groups were combined, the ejection fraction was significantly higher (32.2 ± 9.27; p<0.05)
at follow-up compared to baseline (29.9 ± 8.80). We found that heart rate was significantly lower at
follow-up (89.9 ± 14.6 beats/min) compared to baseline (93.4 ± 17.2; p<0.05) only in the managed
care group. Furthermore, if diastolic blood pressure increased over the follow-up period, ejection
fraction fell by 5.98% (p=0.009) in comparison to cases where diastolic blood pressure remained the
same or fell. In addition, thiamine levels at baseline correlated negatively with systolic blood
pressure (r=-0.68, p=0.04) at follow-up.
Conclusion: Non-communicable heart disease and other diseases of lifestyle, such as high blood
pressure, obesity and diabetes, are drastically increasing in Sub-Saharan Africa in general and in a
black urban African community, such as Soweto, specifically. Soweto can clearly be described as a
community in epidemiological and nutrition transition and is facing a double or even triple burden of
disease. This is a community that is still being burdened by historically prevalent forms of
communicable or infectious diseases juxtaposed against people who have lived their whole lives in
Soweto and are increasingly suffering from newer or non-communicable diseases of lifestyle.
Women seem to be especially burdened by this increase in non-communicable diseases, with a
predominance of women suffering from heart disease and obesity. Certain exacerbating risk factors
have been identified from the HOS in this community, namely the gender specific effects of sleep,
smoking and other environmental factors on BMI and blood pressure, and the adverse effects of
changing dietary patterns particularly the increased consumption of refined and processed foods,
high in sugar, salt and fats and insufficient intakes of fruits and vegetables.
Although there are some limitations to our HF management study, it serves as an indication that
targeted, culturally sensitive care, adapted to an urban African population, might contribute to
improved patient outcomes. However, prevention should always be our first priority through
community-based and gender specific screening and the development and implementation of
targeted prevention programs. / MT2017
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/22199 |
| Date | January 2016 |
| Creators | Pretorius, Susan S |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
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