Author + information
- K. Srinath Reddy, MSc, MD, DM∗ ()
- ↵∗Reprint requests and correspondence:
Dr. K. Srinath Reddy, Public Health Foundation of India, ISID Campus, First Floor, 4 Institutional Area, New Delhi 110070, India.
Today's risk behaviors become tomorrow's risk factors, and today's risk factors become tomorrow's cardiovascular events. The policy construct that guides programs for health promotion and prevention of cardiovascular disease (CVD) springs from sound scientific evidence that this temporal sequence can be successfully interrupted. Although much of this evidence has been gathered in high-income countries where the CVD epidemic matured over a century, it is readily applicable to many low- and middle-income countries that are currently experiencing rapid health transition (1).
CVD prevention is possible through 3 approaches: primordial, primary, and secondary. Primordial prevention refers to averting the acquisition or augmentation of risk behaviors and risk factors in the first place. This approach is applicable not only to populations that are at an early stage of epidemiological transition but also to children in all countries. Primary prevention involves early recognition and elimination or reduction of established risk behaviors and risk factors; the goal is to prevent their progression to CVD events. In every population, there will be such individuals at “high risk” who require to be moved to lower levels of absolute risk. Secondary prevention is directed at persons who have clinically manifested CVD; it involves altering risk behaviors and risk factors to minimize the recurrence of major cardiovascular events.
Although these stages of prevention seem to be sequential across the life course, they may also overlap. Successfully motivating a teenager who has developed a habitual unhealthy diet to switch to healthier patterns, while simultaneously convincing him or her to stay away from tobacco, is a combination of primary and primordial prevention. Another example of primordial prevention is preventing a young adult smoker from becoming obese while providing support for tobacco cessation. The practice of cardiovascular health promotion and disease prevention must overcome arbitrary divisions imposed by such a classification of convenience. Instead, it must address the composite risk profile of subjects, which arises from a combination of current risk behaviors and risk factors as well as their vulnerability thresholds for moving toward higher levels of risk through adoption of new risk behaviors or careless neglect of existing risk factors.
Risk is not only addressed at the level of persons (individuals) but also at the level of communities (people) and countries (populations). Population-based strategies use impersonal interventions, such as tobacco taxes or a ban on trans-fats in processed foods, to reduce risk across the entire population. Other actions occur at the level of community, such as creation of safe pedestrian pathways and cycling lanes or ensuring that public areas and workplaces are free from tobacco smoke. It is the responsibility of health services to provide personalized care for primary or secondary prevention. Policy instruments, community empowerment, and individual risk reduction strategies are synergistically complementary. Together, they help to create a social environment that is conducive for individuals to make and maintain healthy living choices throughout their lives and to craft a caring health system that provides health protection from home to hospital.
These lessons are clear from the experience of high-income countries, such as Finland, Australia, New Zealand, Canada, the United Kingdom, and the United States, which have witnessed the rise and fall of age-standardized CVD mortality rates over the last century (2,3). However, they have not yet been adopted by large, developing countries such as China and India, which are now experiencing an upswing in CVD mortality. The course of the global CVD epidemic in the 21st century will be determined by how these and other developing countries counter, contain, and curb the threat that CVD poses to health and the economy.
It is in this context that the results of the study by Bi et al. (4) in this issue of the Journal are worrisome. China has displayed an upward trajectory in the incidence of CVD over the last 3 decades. The high prevalence of CVD risk behaviors and risk factors in the adult Chinese population, as revealed in this nationally representative survey, raises the specter of a further rise in CVD mortality attributable to CVD in the coming decades. There is an urgent need to pursue proven pathways of prevention, to swiftly and successfully stall this stampeding epidemic, to ensure that only a small fraction of major CVD events occurs in subjects >70 years of age.
Within the CVD spectrum, China has experienced higher disease burdens from stroke than from coronary heart disease, which remained low compared with many other countries (5). However, there are indications of increasing coronary risk: Chinese smokers consume one-third of the world's production of cigarettes; China has the largest number of subjects with diabetes, with a projected rise to 130 million by 2030; and mean population levels of plasma cholesterol have increased in recent years. If these trends are not reversed through effective prevention strategies, China cannot escape the coronary epidemic, even as stroke mortality rates remain high.
Why measure cardiovascular health in a population rather than risk? The conventional approach to risk assessment in subjects has depended on dichotomous categorization of individual risk factors on the basis of clinically relevant cutpoints. However, observational epidemiology has shown a continuously rising risk of coronary heart disease with increasing values of variables such as blood pressure, plasma cholesterol, blood sugar, and number of cigarettes smoked. Although composite estimates of absolute risk are useful in individuals, estimating the number of people at risk in a population is difficult because multiple risk factors are distributed differently in the population, with variable risk gradation across each distribution. The concept of cardiovascular health seeks to estimate the proportion of persons in a population who have an absence of risk behaviors or risk factors on the basis of acceptable criteria. It calls for active efforts to keep the population healthy rather than merely attempt to reduce risk factors that have been passively permitted to rise.
Although the observation by Bi et al. (4) that only 0.2% of the Chinese adult population had all 7 ideal cardiovascular health metrics seems alarming, the fact that 76.8% were within the range of 3 to 5 metrics holds hope for improvement through effective prevention programs. Men were worse off than women, mainly because of a very high differential in the prevalence of smoking (56.6% vs. 2.7%). Although <2% of adults met the composite criteria for a healthy diet, this dismal figure may be an aberration because of the questionable choice to substitute soy protein (which the investigators could estimate) for whole grains (which they could not) in the diet score; only 0.3% met the soy goal. It is worth noting that only 8% met the sodium goal and, not surprisingly, only 26.1% had an ideal blood pressure. One-third of the adults did not have an ideal body mass index. All these factors are areas for intensified action to improve cardiovascular health.
For several variables, proportions of the population meeting the ideal goals fell with increasing age and economic development (4). This outcome is consistent with an intermediate stage of demographic and developmental transition. However, education had a positive effect on the cardiovascular health profile. This finding holds the promise of improving health behaviors through well-designed programs that effectively enhance knowledge, motivation, and skills. Policies must aim to protect the mostly nonsmoking Chinese women from falling victim to the tobacco industry's targeted marketing (primordial prevention) and to protect the mostly smoking Chinese men from that deadly habit (primary prevention).
China's government needs to make clear choices on how it wishes to balance its rapid economic development with protection of the cardiovascular health of its population. It cannot defend its state-owned tobacco industry and permit air pollution levels to rise across the country without imperiling the health of the present and future generations of the Chinese people. Population-based strategies to improve composite diets must result in moderation of salt intake and higher consumption of fruit and fish. Health services must strengthen their capacity for risk detection and reduction in clinical settings: developing countries experience high event rates even at modest levels of risk factors, when their health systems are not geared up to meet the challenge of an expanding CVD epidemic (6). In many areas of development, China has demonstrated that it can combine resolute political will with exceptional operational skill, to move rapidly from intent to implementation. Can it do the same for cardiovascular health?
↵∗ Editorials published in the Journal of the American College of Cardiology reflect the views of the authors and do not necessarily represent the views of JACC or the American College of Cardiology.
Dr. Reddy has reported that he has no relationships relevant to the contents of this paper to disclose.
- American College of Cardiology Foundation