Population risk factor control in the 21st century

In January, 2016, the American Heart Association (AHA) called for a “moonshot project… to end coronary heart disease and its consequences” (https://www.onebraveidea.com). In response, hundreds of investigators around the world contributed their proposals, each with its own “Brave Idea”. AHA's provocative stimulus to develop an Endgame strategy continues to be influential in thinking about our near-term and longer-term cardiovascular future.1 Truly to end coronary heart disease (CHD) requires removal of its causes—broadly, virtually eradicating hypertensive and atherosclerotic diseases. The impact on individual and population health would extend beyond CHD to include the other major cardiovascular and cerebrovascular diseases (CVDs). This would be the challenge and the ultimate health outcome of a CVD Endgame. Since the mid-20th Century, a cornerstone of CVD prevention has been detection and treatment, or “control,” of risk factors in order to prevent first major cardiovascular events—primary prevention. As articulated by Rose in 1981, primary prevention applies to both individuals and populations, in the “high-risk” and “mass” or “population-wide” strategies.2 They aim to reverse the present risk of individuals at the extreme or to shift the current adverse risk distribution in populations to more favorable levels. The impact of these strategies has been demonstrated many times—for example, through the CHD IMPACT Model applied to reductions in CHD mortality in several countries, including the United States.3 But, notably, these strategies share two limitations. First, they are remedial in orientation: Their primary purpose is to reduce risk already present in individuals and populations, and their impact is impeded by well-known and persisting barriers. Second, they do not address the incidence of risk and therefore offer no relief from the Sisyphean task of risk factor “control”. An important complement to primary prevention is to prevent CVD risk “in the first place,” thereby averting development of high individual risk and adverse population risk distributions. This approach is promotion of ideal cardiovascular health (CVH), through the strategy of primordial prevention.4 As early as 1957, in the Framingham Heart Study, it was noted that among middle aged men those at the lowest levels of blood pressure, relative weight, and cholesterol had CVD incidence rates even lower than those of all women of the same age.5, 6 But the primary interest then and in subsequent decades was in persons at highest, not lowest, risk. Forty years later, in 1999, Stamler and others demonstrated significantly lower cardiovascular mortality and greater life expectancy among persons who were at lowest levels of cholesterol and blood pressure and were non-smokers free of diabetes, history of myocardial infarction, or known EKG abnormalities.7 The authors concluded: “A substantial increase in the proportion of the population at lifetime low risk could contribute decisively to ending the CHD epidemic.” Work in the decade that followed added substantially to the evidence indicating benefit of low risk for lifetime cardiovascular event rates, quality of life, and health care costs.8-10 Thus, by the end of the first decade of the 2000s, the case for a new approach to the CVD problem was clearly emerging. Accordingly, in 2010, the AHA adopted a concept that reframes our perspective on the societal cardiovascular problem by viewing it in terms of health and not disease alone. “Cardiovascular health (CVH)” became defined by 7 metrics—healthy diet, physical activity, and body weight; no smoking; and optimal blood pressure, cholesterol, and glucose. Each metric is stratified as ideal, intermediate, or poor, separately for adults (age 20 years and over) and children (under age 20). Each metric and a simple additive score are monitored continuously for the US population through the National Health and Nutrition Examination Surveys (NHANES). This concept was incorporated in AHA's Strategic Impact Goal for 2020: “…to improve the cardiovascular health of all Americans by 20% while reducing deaths from cardiovascular diseases and stroke by 20% by 2020”.11, 12 CVH remains an underpinning of AHA's updated focus for 2030.13 Strasser, in 1978, proposed a population strategy that would “protect whole societies from the penetration of risk factor epidemics”.4 The term “primordial prevention” was introduced to designate this new strategy and distinguish it from the conventional primary, secondary, and tertiary CVD prevention. Though the term and the concept have been cited many times over the ensuing years, implementation of primordial prevention in practice has been quite limited. Recently it has received more prominent attention.14 Now, the time has come to pursue it aggressively. Primordial prevention is necessary to achieve the goal of improved population CVH and is an essential component of the CVD Endgame. Primary prevention will remain necessary, so long as risk factor epidemics persist. But as primordial prevention becomes widely and effectively implemented, reliance on the more downstream strategies of CVD prevention will decrease. Given that CVD risk in adulthood has its beginning in early childhood, a critical question regarding primordial prevention is, How early is early? Currently in the United States, the 7 established metrics are first fully captured by NHANES in adolescence. The full set of requisite data is not collected below age 12.15, 16 Only partial characterization of CVH is possible at earlier ages except in specific population studies. Even so, it is clear from available data that prevalence of ideal CVH declines sharply through childhood and adolescence into early and mid-adulthood, from about 50% at age 10 to 10% at age 50.1, 17 Recent research has led to studies at successively earlier stages of development and maturation—not only in childhood—from conception through fetal development and infancy.18 Pre-conception health status of the mother and father are being studied as well. But limitations of definition and measurement pose obstacles at these earliest stages of life. What are meaningful CVH metrics at the beginning of life? What is the prevalence of ideal CVH at birth, with what disparities by race/ethnicity, geography, and economic status? What are the population distributions and trajectories of CVH metrics into adulthood? Establishing the ability to measure, monitor, and potentially to modify CVH trajectories from the beginning of life has become a priority focus of ongoing research, as discussed in a recent AHA/NHLBI Symposium (report in preparation). While this work moves forward, the opportunity should be seized to develop and implement an Endgame plan that focuses on primordial prevention of risk factors, while continuing primary prevention efforts where effective, and striking a new balance in investment so as to prevent CVD risk in the first place, not only to remedy it when already present. Immediate steps for the Endgame are to define the key elements of the strategy; accelerate progress in science, policy, and practice; and seize the opportunity of a potential new era in public health and prevention. It is clear that ideal CVH in middle age predicts virtual absence of CVD but is rare at this age, having declined sharply from early in life.17 Mobilizing substantial commitment to CVH promotion, through primordial prevention, will be necessary to achieve the goal of the Endgame. Further, the Endgame requires a quantitative target and time-specific goals. The key elements are to: (a) increase prevalence of ideal CVH, to replace CVD as the societal norm; (b) promote and preserve ideal CVH from the beginning of life to middle age and beyond, to implement a true life course strategy; and (c) set the timeline, to stimulate and catalyze public health action. How high the prevalence, at what age, by when? The proposed interim target is to achieve 50% or greater prevalence of ideal CVH for all population groups, sustained to at least age 50 years, by 2050 or sooner: “50 × 50 × 50” (Table 1).1 This simple concept is represented graphically in Figure 1. While advances in science are narrowing important gaps in current knowledge bearing on the Endgame strategy, much of what is already known remains to be translated into policy and implemented in practice. Priorities for action in each of these areas are outlined in Table 2. The CVD Endgame—CVH replacing CVD in this century—is proposed as the means to fulfill our decades-long efforts in risk factor control, ultimately to accomplish the goal of primordial prevention by protecting whole societies from ongoing risk factor epidemics. The impetus to ending the immense societal burden of CVD, knowledge to date of the limitations as well as the impact of primary CVD prevention, and the untapped potential of promotion and preservation of CVH combine to stimulate this new approach to the CVD problem. While the coronavirus pandemic overshadows other public health priorities at this moment, thoughtful consideration of its aftermath is needed now. It is difficult to foresee precisely what impact this pandemic may have on the world economy, public health infrastructures and resources, and societal values regarding health and well-being. But an unexpected opportunity is presented to create a new public health infrastructure and workforce as envisioned by Koh and Sibelius, who wrote in 2010 of the Affordable Care Act: “…we believe that the Act will reinvigorate public health on behalf of individuals, worksites, communities, and the nation at large… and will usher in a revitalized era for prevention at every level of society.”19 This vision, if realized, would greatly strengthen a public health framework in which the CVD Endgame could be fully executed to attain its long-sought goal. Perhaps lessons from the new global pandemic will contribute to resolving the longstanding cardiovascular one. None. The author is solely responsible for all aspects of the submitted work.