The prescience of Shaper and Jones
Shaper and Jones are to be lauded for identifying the central role of cholesterol in determining variation in risk of coronary disease among different ethnic groups in Africa as early as 1959.1 Their publication followed closely the 1957 Seven Countries Study by Ancel Keys, which established unequivocally the pathophysiological role of dietary saturated fats acting through serum cholesterol concentrations in the causation of atherosclerotic vascular disease.2 The prescience of Shaper’s study of coronary artery disease is thrown into sharp relief because it challenged the prevailing assumption then that variation in risk of disease in Africans compared with Caucasians was genetic in origin; Africans were considered to be almost ethnically immune to the development of coronary artery disease.3,4 In fact, Shaper and Jones avoided the ‘racial profiling’ that was prevalent at the time by focusing in their study on measuring key components of environmental exposure, i.e. dietary composition. They identified the contribution of two of the main components of the diet–heart hypothesis to risk of coronary disease in Ugandans of African origin and those from the Indian subcontinent: (i) the intake of total fats, and proportion of animal (saturated) and plant (unsaturated) fats in the diet; and (ii) intake of vegetables and unrefined staple foods (i.e. vegetables, pulses and ground provisions—such as yams). They also hinted at the conditioning effect on risk of other lifestyle attributes, such as physical activity, but omitted mention of tobacco use. Since then, a large and robust literature has confirmed that the relationships between common cardiovascular disease risk factors and acute myocardial infarction are similar throughout the world.5
The surprising omission from their report was an index of obesity; there is no information on weight or height or any measure of body size or composition. The association between overweight and coronary disease was well established by then.6 Perhaps, the focus on cholesterol as a major risk factor modifiable by simple dietary changes was the sole aim of the communication. Perhaps, also, they were correct to ignore easily measured indices of obesity such as BMI because of the recognized variation in proportion of fat and lean mass at any BMI and the consequent variation in risk that is mechanistically associated with adiposity. Certainly, relative weight captured as the BMI and cardiovascular risk are not absolutely correlated, as has been demonstrated in the Seychelles and South Africa.7,8 Although obesity has increased in the Seychelles and South Africa, mortality from coronary artery disease appears to be falling in both African countries.9–11 A current enumeration of the main risk factors for coronary disease would not differ substantially therefore from Shaper’s early framework; thus, almost nothing significant has been observed about risk of coronary artery disease that is not in the article, except for cigarette smoking and the variation in underlying susceptibility to risk exposures that is conditioned by early life development.12 The initial recognition by Barker and the subsequent elaboration of understanding of this variation in underlying susceptibility to the pathogenetic force of risk factors arising from developmental modulation of individual form and function is a major advance in the understanding of disease risk.13 Ironically, it comes perilously close to rehearsing old fallacies of the genetic basis of observed ethnic differences in disease profile because of the divergence of ethnic biological phenotypes, driven by generations of environmentally entrained epigenetic control of development early in life.14
Are we any further along on prevention than we were then?
The study was conducted >50 years ago when coronary artery disease was almost non-existent in Black people of Uganda and the rest of the continent.3,15 According to the latest WHO data published in April 2011, coronary artery disease caused 13 569 or 3.65% of total deaths in Uganda, with an age-adjusted death rate of 130.92 per 100 000 of population, which ranks number 69 in the world.16 Although an upward trend in the incidence of coronary artery disease among Africans has been reported,17–19 the rates of coronary heart disease as a cause of heart failure remain relatively low in Southern, Eastern, Central and Western Africa compared with other regions of the world.20–22 Furthermore, there is a glimmer of hope that in middle-income African countries that have implemented preventive measures, such as stringent anti-smoking legislation,23 the mortality rate from coronary artery disease is falling,10,24 highlighting the fact that coronary artery disease is preventable through attention to the environmental exposures that were identified by Shaper and Jones.
What about the future?
Africa has the historic opportunity for avoiding the epidemic of coronary artery disease before it takes root on the continent by adopting public health best practices.19 African governments need to develop intersectoral policies and targets for prevention of coronary artery disease, such as those of South Africa,25 which are aligned with the United Nations high-level meeting on non-communicable diseases.26 The critical issues that need to be resolved to ensure that recent political commitments are translated into practical action include the following: (i) adopting a life course approach to the prevention of cardiovascular and other non-communicable diseases (NCDs); (ii) measuring the burden of NCDs at a population level to inform government and donor funding commitments and priorities for intervention; (iii) finding the right balance between the relative importance of treatment and prevention to ensure that responses cover those at risk, and those who are already sick; (iv) defining the appropriate health systems response to address the needs of patients with diseases characterized by long duration and often slow progression; (v) research needs, in particular translational research in the delivery of care; and (vi) sustained funding to support the NCD response of developing countries.27
These responses need to take cognizance of the heavy burden of infectious diseases as the leading causes of mortality in sub-Saharan Africa, and address the interaction between infectious diseases (such as HIV/AIDS and tuberculosis) and chronic diseases (such as chronic obstructive lung disease and diabetes).28,29 In addition to the heavy burden of infectious diseases, and the emergence of chronic non-communicable disease, many communities in sub-Saharan Africa also suffer from unacceptably high mortality from preventable perinatal and maternal conditions, as well as injury and violence. The quadruple burden of communicable, non-communicable, perinatal and violent deaths is producing a complex health transition, which demands an extraordinary response.9,30 For example, the persistent burden of malnutrition in young children yet growing overweight and obesity among adolescents generates the ‘perfect mix’ of factors for later cardiometabolic disease.31,32 At the other extreme, HIV prevalence among older persons is far higher than previously recognized, underlining the importance of chronic comorbidities and posing unexpected, growing challenges to primary care practice.33 The importance therefore, of understanding health and illness along the life course, and where to intervene, is paramount in developing the agenda for prevention of cardiovascular and other diseases in Africans beyond the era of Millennium Development Goals.
Conflict of interest: None declared.