Heart of Soweto Study
Research Stream: International health / Individuals living in low-to-middle income countries
While the burden of cardiovascular disease (CVD) states such as heart disease, is stabilising in high income countries, in low-to-middle income countries (LMIC) it continues to rise . With scarce health care resources, LMIC are typically ill-equipped to cope with new challenges  when already over-burdened by illness related to malnourishment and infection . There is little scope to tackle new prototypes of heart disease arising from changing risk behaviours due to epidemiologic transition . Contemporary studies demonstrate high levels of non-communicable antecedents of heart disease (except dyslipidaemia) in sub-Saharan Africa; particularly urban communities [5-7].
It was within this context, that we established the now world-renowned Heart of Soweto – the largest and most comprehensive study of heart disease on the continent – focusing on presentations of heart disease to the Chris Hani Baragwaneth Hospital servicing the largest urban African community on the continent.
Full Study Title
Heart of Soweto Study
This study was predominantly funded via internal support provided by the University of the Witwatersrand and Baker IDI Heart and Diabetes Institute in addition to critical support from Adcock-Ingram; the Medtronic Foundation; BHP Billiton; and Servier.
Rationale for the Study
As the global epidemic of CVD continues to rapidly evolve, the burden of disease is shifting. At the beginning of the century, CVD accounted for less than 10% of all deaths worldwide. By 2001, Murray and Lopez’s prediction that CVD would emerge as the leading cause of death and disability by 2020 was truly evident.  In addition, much of the global CVD burden (80%) is being carried by LMIC (defined ross national income per capita lower than US $9200) who even today, are still grappling with poverty-related diseases, infectious diseases and inadequate health care facilities . In Africa, CVD and its most common form in the western world (heart disease) is traditionally caused by non-ischaemic pathology; led primarily by cardiomyopathy, rheumatic heart disease, and less so by tuberculous pericarditis and pulmonary heart disease. However, there is emerging evidence in sub-Saharan Africa, both in respect to mortality and morbidity rates, that CVD is both an increasing and evolving public health issue in the region.
The overall aim of the now world-renowned Heart of Soweto Study was to systematically study and understand an evolving epidemic (as the target community underwent epidemiological transition) of heart disease in sub-Saharan Africa’s largest urban community – SOWETO in South Africa. In addition to documenting important trends in respect to heart disease in Soweto, we aimed to develop innovative health care services to tackle this challenging health care issue, as well as extend our efforts to the primary care setting and wider Africa.
The 3,500 bed Chris Hani Baragwanath Hospital (case load of > 125,000 in-patients per annum) services the tertiary care needs of Soweto and surrounding communities. With no other major facilities and limited private health care, it represents a key barometer of the overall health of Soweto. All cases of suspected heart disease are referred to the Cardiology Unit for advanced diagnostic testing and gold-standard treatments. A prospective clinical registry of all de novo presentations was established in 2006 as part of the Heart of Soweto Study; sub-Saharan Africa’s largest and most detailed study of advanced forms of heart disease to date.
During 2006-2008, we captured data on 6006 de novo presentations to the Cardiology Unit. Excluding those 678 cases (11%) found not to have significant disease or risk, the remainder (n = 5328) were referred on the following basis:
- Emergency presentation (n = 401, 7.6% of total case-load)
- External referral from local primary care clinics for advanced assessment and definitive treatment (n = 367, 6.8%)
- Internal referral of a patient as a current hospital inpatient (n = 1,992, 37.4%)
- Referral from another outpatient department (n = 2,568, 48.2%)
We systematically captured data from all de novo presentations of suspected heart disease (focusing on ‘new’ vs. historically prevalent forms) during 2006–2008. There were 3,168 female (52±18 years) vs. 2,160 male (53±17 years) cases. Overall, 999 (19%) presented with uncomplicated hypertension (n = 988) or type II diabetes, 1,862 cases (35%) ‘new’ heart disease (1,146 and 581 cases of hypertensive heart failure and coronary artery disease), and 2,092 cases (39%) of historically prevalent heart disease (including 724 with primary valve disease and 502 idiopathic dilated cardiomyopathies). Level of education and non-communicable risk factors were important correlates of advanced disease. The rate of historically prevalent cases was higher in those aged 20–49 years (19–60 cases/100 000 population/annum) whilst being higher for “new” heart disease in those aged >50 years (155–343 cases/population/annum). Historically prevalent heart disease cases were younger [adjusted odds ratio (OR) 0.98, 95% 0.97–0.99 per year], more likely to be African (OR 4.59, 95% 2.76–7.60) while being less likely to originate from Soweto (OR 0.87, 95% 0.75–1.00) and be female (OR 0.67, 95% 0.49–0.92).
Ongoing Research/Translational Potential
The results of the Heart of Soweto study have been instrumental in changing national (including South African health care policies) and international perspectives on communicable and non-communicable heart disease in sub-Saharan Africa. In addition to prompting the initiation of the PROTECT AFRICA Study it has proved to be the stimulus for other surveillance studies throughout the continent.
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