Burden of the Disease, Condition, or Risk Factor
Epidemiological data on blood pressure, cholesterol, and bodyweight levels are predominantly available from developed countries; however, evidence indicates that these risk factors are important and increasing in many other countries. Surveys in developing countries suggest increases in these risks occur early in the path to industrialization (Bobak and others 1997; Evans and others 2001; Suh 2001; Wu and others 1996). Good evidence also documents risk-factor levels rising after people migrate to more urbanized settings (Poulter and Sever 1994) in Africa (Poulter 1999; Poulter, Khaw, and Sever 1988), China (He, Klag, and others 1991; He, Tell, and others 1991), and the Pacific islands (Joseph and others 1983; Salmond and others 1985; Salmond, Prior, and Wessen 1989). The World Health Organization's Global Burden of Disease study demonstrated that CVD was a leading cause of death in many regions and that most adults in developed and developing countries have nonoptimal blood pressure, cholesterol, and bodyweight levels (Ezzati and others 2004; WHO 2002). Indeed, even using traditional cutoff points, these risk factors are prevalent: of 140 subgroups defined by age, sex, and region, 45 percent had a mean SBP equal to or greater than 140 mmHg, 25 percent had mean cholesterol levels over 5.5mmol/l, and 45 percent had mean BMI levels of at least 25 kg/m2.
Health Burden
The Global Burden of Disease study assessed the burden attributable to nonoptimal levels of these risks (table 45.1) (Ezzati and others 2004; WHO 2002). The burden for blood pressure was related to deaths and disability-adjusted life years (DALYs) from IHD, stroke, hypertensive disease, and other CVD; endpoints for cholesterol included IHD and stroke; and endpoints for BMI were IHD, stroke, hypertensive disease, diabetes, certain cancers, and osteoarthritis. Globally, 7.1 million deaths were attributed to high blood pressure in 2000, 4.4 million to high cholesterol, and 2.6 million to high BMI. This burden was shared approximately equally among the sexes. A large fraction occurred in middle age, especially in developing countries, and this factor, together with the frequently debilitating nature of nonfatal CVD, accounted for a large number of DALYs.
[Table .]
More of the DALY burden was experienced in developing countries than in developed countries, reflecting the large populations in developing countries and their already high risk-factor levels. In all regions, most CVD is attributable to the combined effects of high blood pressure, cholesterol, and bodyweight levels (figure 45.2).
[Figure
45.2]
Table 45.2 shows the burden resulting from the overlapping or multicausal etiology of diseases. Analyses of the combined impact of these and other major cardiovascular risks indicate that the joint contribution of established risks is responsible for 83 to 89 percent of the IHD burden and 70 to 76 percent of the stroke burden worldwide (Ezzati and others 2003; Ezzati and others 2004).
[Table .]
Financial Burden
The economic impact of high blood pressure, cholesterol, and bodyweight levels can be estimated indirectly using the foregoing data—namely, that more than two-thirds of the CVD burden can be attributed to those risks. In addition, more than three-quarters of type 2 diabetes is caused by high bodyweight (Ezzati and others 2004; WHO 2002). Hence the economic impact of nonoptimal levels of those risks will be at least two-thirds that due to CVD and diabetes. A recent report highlighted the economic impact of CVD in developing economies, noting that a high proportion of the CVD burden occurs among adults of working age (Leeder and others 2004). In Brazil, China, India, Mexico, and South Africa, conservative estimates indicated that at least 21 million years of future productive life are lost because of CVD each year. Although no detailed data exist on the direct economic burden of the individual risk factors, the costs of CVD treatment in developing countries are significant. In South Africa, for example, 2 to 3 percent of gross domestic product was devoted to the direct treatment of CVD, or roughly 25 percent of all health care expenditures (Pestana and others 1996). For many middle-income countries, high body mass is already an important cause of health inequities (Monteiro and others 2004).
Current expenditure in developed countries provides an indication of possible future expenditure in developing countries. For example, estimated direct and indirect costs of CVD in the United States were US$350 billion in 2003. In 1998, US$109 billion was spent on hypertension, or about 13 percent of the health care budget (Hodgson and Cai 2001). Studies are limited but suggest that obesity-related diseases are responsible for 2 to 8 percent of all health care expenditures in developed countries. For example, in 1991, 2.5 percent of health care costs in New Zealand were attributable to obesity (Swinburn and others 1997), and in 1996, US$22 billion was attributed to obesity-related CVD in the United States, equivalent to 17 percent of CVD-related health expenditures (G. Wang and others 2002).
