Reducing the Global Burden of Cardiovascular Disease: The Role of Risk Factors

James W. Levenson, MD, MPH, Patrick J. Skerrett, MS, J. Michael Gaziano, MD, MPH

Disclosures

Prev Cardiol. 2002;5(4) 

In This Article

Future Challenges

While the concept of the epidemiologic transition offers tremendous insight into how and why CVD is emerging as the predominant global cause of morbidity and mortality, it does not mandate that this must be so. As can be seen in the experience of the EstME countries, CVD rates rise -- and fall -- in a predictable fashion with changes in rates of risk factors and behaviors. This raises the possibility that manipulating risk factor rates can blunt the increase in CVD that accompanies the shift from the age of pestilence and famine through the ages of receding pandemics and of degenerative and delayed, man-made diseases, and hasten the decline in CVD in the age of delayed degenerative disease. The transfer of lower-cost health and food technologies from the EstME countries to those in the DevE group has accelerated the fight against communicable diseases and is clearly helping speed the transition out of the age of pestilence and famine. It is possible that interventions aimed at risk factors could reduce the burden of CVD. Given the multifactorial nature of CVD, no single solution will be applicable to all geographic and economic regions of the world. In this section, we outline the major challenges facing countries in each of the three economic categories, as well as various ways to address these challenges.

Three complementary strategies may be used to reduce morbidity and mortality from CVD. First, implementing population-wide public health measures may lower the overall burden of CVD risk factors in the entire population. Such measures include detection and surveillance strategies, public education campaigns, and the institution of low-cost preventive interventions. National campaigns against cigarette smoking are an example of this approach. The second strategy involves identifying and targeting higher-risk subgroups of the population that will benefit most from moderate, cost-effective prevention interventions. The third strategy involves delivering acute and chronic higher-cost treatments and secondary prevention interventions to those with clinically manifest disease. Typically, resources are allocated simultaneously to all three strategies. However, this three-pronged approach has been implemented mostly in EstME countries with abundant financial resources for health care.

While CVD mortality rates have fallen in most EstME countries, several important challenges remain. First, socioeconomic and racial disparities in CVD rates continue to linger. In the United States, for example, while population-wide rates of CVD mortality have fallen over the past 40 years, there are still wide disparities across racial and ethnic boundaries.[45,46] Thus, a major goal will be to ensure that all racial, ethnic, and socioeconomic groups have the same access to preventive and therapeutic technologies. Second, the rate of decline in CVD mortality appears to be slowing. This may stem from troubling trends in a number of coronary risk factors -- increases in smoking among young adults and teenagers, particularly young women; slight decreases in the rate of appropriately treated hypertension; and rapidly accelerating rates of obesity, DM, and physical inactivity, especially among children and young adults. Taken together, these trends may explain why mortality curves are flattening out and why mortality rates have fallen faster than CVD incidence rates. More public health dollars need to be directed at antismoking efforts that target high-risk groups and at broader application of guidelines for detecting and managing hypertension and hyperlipidemia. Effective strategies to increase activity and reverse trends in obesity and DM must be developed and implemented. Third, the prevalence of CVD will continue to increase with a population's increasing mean age, even if that population's age-adjusted mortality rates continue to decline. Finally, incremental advances in therapeutic health technology and secondary prevention have led to increasing numbers of people surviving with CVD, which consumes increasing amounts of resources. A major challenge for most EstME countries will be to develop more efficient and cost-effective strategies for treating CVD.

The countries in this group are largely in the third phase of the epidemiologic transition. However, the resources they have available for health care are often distressingly low. Median annual per capita expenditures for health in the emerging and developing market economies is $130, a fraction of the $3700 spent on health care per capita in the United States.[47] This mandates making careful choices in terms of allocating health care dollars to each of the strategies outlined above.

In the EmgME countries, the two overarching goals are managing the increasing number of people with CVD and hastening the transition from the third to the fourth phase of the epidemiologic transition. This will likely enhance overall productivity in the region because during the third phase, CVD (particularly CHD) often afflicts those in the ages of highest productivity. All countries in this economic sector need more careful tracking and assessment of CVD rates and risk factors, especially population-attributable risk. This will allow more careful allocation of scarce preventive resources.

National guidelines that have been developed by EstME countries, such as the sixth report of the (US) Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure,[20] the second report of the (US) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults,[48] clinical guidelines on the identification, evaluation, and treatment of overweight and obesity in adults from the US National Heart, Lung, and Blood Institute,[49] and recommendations of the Second Joint Task Force of European and Other Societies on Coronary Prevention[50] need to be adapted for and adopted by EmgME countries. Governments should initiate major initiatives aimed at lifestyle factors, such as reducing smoking rates, improving the diet, and increasing physical activity. Public health priorities should include smoking cessation and the detection and control of hypertension, both of which are highly cost-effective. The targeting of higher-risk individuals for higher-cost preventive strategies, such as pharmacologic cholesterol lowering, will need to be confined initially to urban centers, where the burden of CVD is high and the necessary laboratory-based health care infrastructure is available.

Throughout this economic sector, improvements in health care delivery systems are needed in order to manage the already high rates of CVD. Careful attention must be paid to the transfer of lower-cost health technology, keeping in mind the considerably lower annual health care expenditures in the EmgME countries compared to those in the EstME. Such interventions as the more widespread and appropriate use of aspirin and blockers during acute myocardial infarction[51] are examples of extremely cost-effective, life-saving therapies that should be implemented universally before extensive resources are directed at higher-cost interventions, such as angioplasty and bypass surgery. In addition, manpower issues must also be addressed, with greater attention paid to excessive specialization and improved education of health care workers.[52]

The problems facing the DevE group may be the most challenging. In these countries, a rapidly increasing burden of CVD is appearing early in the epidemiologic transition and the per capita resources needed to create an effective public health and health care infrastructure are generally not available. In many DevE countries, per capita health care expenditures are less than $50 per year.[53] In addition, a number of other national priorities, including the stimulation of economic growth, social and political change, and the devastation wrought by communicable diseases, compete for limited funding.

Rising CVD rates will eventually exert a drag on economic growth. The loss of the head of a household from CVD (or any other disease) has a devastating impact on the health and well-being of the entire family. In Bangladesh, for example, when an adult dies, a child who depends on that adult has a 12-fold higher probability of death.[54] At present, data on the economic consequences of CVD in the DevE group are limited. Much more work is needed to refine estimates that would permit more thoughtful allocation of health care resources.

As mentioned earlier, the epidemiologic transition has been accelerated in many DevE countries, in part by an efficient transfer of risk factors and risk behaviors from the EstME to the DevE. Thus, a major challenge for developing countries is to attempt to alter the natural history of the epidemiologic transition and to limit the increase in CVD-related risk factors. That such alterations are possible is evident from the experience of Japan, in which CHD rates were kept relatively low during a fairly rapid economic transition from an agriculture-based economy to an industry-based economy. While imbedded cultural practice, such as diet, likely played a large role, the Japanese experience illustrates that the nature of the transition is mutable.

As is true for the EmgME countries, a critical first step in developing a comprehensive plan for many of the DevE countries is better assessment of cause-specific mortality, cause-specific morbidity, and prevalence of major preventable risk factors for CVD. Recently published data from the ongoing Sino-MONICA project in China is an excellent example of this kind of work.[55] Such assessments will allow for better allocation of resources based on country-wide burdens of disease. Government agencies will need to carefully survey and evaluate the major CVD risk factors for which low-cost strategies are available. High priorities include smoking and hypertension, both of which have high population-attributable risks and favorable cost efficacy. The strategy for the detection and management of high cholesterol must be carefully tailored for each region, due to higher treatment costs. While public health approaches aimed at educating the population about diet and exercise may be useful, precise estimates of their cost efficacy are not available even for EstME countries.

Once the initial assessments have been made, guidelines for managing risk factors from a public health standpoint must be developed, based on the population-attributable risk and the available resources. These guidelines must be implemented with low-cost campaigns. Such prevention-directed efforts could blunt the rise in disease rates already apparent in many developed countries. The general shortage of health care professionals in the DevE must also be addressed.

Given the extreme limitations in per capita health care resources in many DevE countries, the allocation of resources to higher-cost strategies for treating CVD may divert resources from the potentially more effective population-wide efforts. Thus, resources directed at interventions and high-technology therapeutics may have to be parsimoniously implemented only in those areas where risk is highest.

Finally, given the wide disparity between health expenditures and resources between the EstMEs and the DevEs, countries in the former group need to expand their aid to developing countries for health care and health care infrastructure. The World Bank estimates that the EstME countries spend only 0.25% of their gross domestic products on assistance to the poorest nations of the DevEs, accounting for approximately $5 billion in health aid annually.

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