Lifestyle and Cardiovascular Health: Title and subTitle BreakIndividual and Societal Choices

As part of the epidemiologic transition into the 21st century, chronic diseases—specifically, cardiovascular diseases—have become the leading cause of death and disability in most countries in the world.¹ Hence, clinical and public health interventions must aim at reducing the burden of cardiovascular disease in populations. Secular trends in cardiovascular disease morbidity and mortality indicate that some progress has been made, and cardiovascular mortality has decreased. However, the incidence of cardiovascular disease has remained largely stable over the past 2 decades, which, given the decrease in cardiovascular mortality, suggests that medical care was a major contributor to the decrease.² These epidemiologic data integrated within the context of unsustainable health care expenses define a burning platform for prevention. Two thought-provoking articles in this issue of JAMA provide an opportunity to reflect on cardiovascular disease prevention and consider the individual vs societal responsibilities in relation to health.

The study by Forman et al³ examines the association between diet and lifestyle and the development of hypertension among women in the Nurses' Health Study. Six modifiable lifestyle and dietary factors were explored for their protective role against hypertension: body mass index less than 25, daily vigorous exercise, a Dietary Approaches to Stop Hypertension (DASH)–style diet, modest alcohol intake, nonnarcotic analgesic use less than once per week, and intake of 400 μg/d or more of supplemental folic acid. Whereas all factors were associated with reduced risk of developing hypertension, body mass index exhibited the strongest association, with a large population-attributable risk equating 40%. If all women were at low risk for the 6 factors, a staggering 78% of new-onset hypertension might potentially be prevented or at least delayed.

The study by Djoussé et al⁴ evaluates the protective association between lifestyle and the development of heart failure among men in the Physicians' Health Study. Six modifiable lifestyle factors (normal weight, not smoking, regular exercise, moderate alcohol intake, consumption of breakfast cereal, and consumption of fruits and vegetables) exhibited a graded inverse association with the development of heart failure. This relationship was strong, as indicated by a lifetime risk of heart failure of 21% in men with none of the factors vs 10% in those with 4 or more desirable lifestyle factors. Importantly, the relationship was robust and persisted when lifestyle factors over time were examined; when factors were restricted to adiposity, smoking, and exercise; and when analyses were restricted to persons with antecedent myocardial infarction, type 2 diabetes mellitus, or hypertension.

The results of these 2 studies must be interpreted in light of several methodological issues. Because both studies pertain to health professionals, mostly white women and men, the results may not be fully applicable to other segments of the population that might differ with regard to sex, race/ethnicity, or knowledge about health and illness. While these aspects are important, they should not be viewed as limitations. Rather, the strength of the association between healthy lifestyle and reduced risk of heart failure and hypertension constitutes an imperative to evaluate these relationships among groups not represented in these cohorts. Both studies are observational, implying that the inferences drawn from them could be affected by bias and unmeasured confounding.⁵ Although randomized trials provide the most robust evidence on the efficacy of therapeutic or preventive measures, a large-scale randomized trial of multiple lifestyle interventions is likely not feasible. Furthermore, it is being increasingly recognized that the generalizability of clinical trials is limited owing to their inherent selection processes,⁶ such that neither study design is ideal and both are complementary. To this end, the effects of lifestyle factors on various forms of cardiovascular disease have been individually documented in randomized trials.^{7 - 10} The present observational studies conducted within rigorously characterized cohorts extend the results of these trials by integrating multiple lifestyle factors, and the graded association between these factors and cardiovascular disease supports a causal relationship.

The study by Forman et al³ relied on self-report to ascertain hypertension, whereas the study by Djoussé et al⁴ relied on self-report to identify heart failure. Thus, in both cases, the outcome status may have been misclassified. Furthermore, because heart failure is a heterogeneous syndrome that can result from systolic or diastolic dysfunction or a combination of both and can reflect several disease entities, chiefly coronary disease and hypertension, it is incompletely characterized by self-report.¹¹ While this consideration is clinically important, it is however less critical from a public health standpoint.

These methodological issues notwithstanding, the studies by Forman et al³ and Djoussé et al⁴ share a common message: healthy lifestyle is associated with reduced risk of both hypertension and heart failure—2 highly prevalent illnesses that are associated with high morbidity and mortality and that have an enormous effect on the individual, society, and health care costs. Importantly, several factors are protective against both conditions. The powerful simplicity of this message begs a reflection on the concept of lifestyle and its implications. Lifestyle is defined as “the typical way of life of an individual, group or culture.”¹² This definition indicates that the notion of lifestyle is not confined to individuals. Yet lifestyle is commonly understood to be synonymous with personal choice and its attendant connotation of right or wrong. However, when considering the lifestyle choices that appear to protect against hypertension or heart failure in the studies by Forman et al and Djoussé et al, it becomes apparent that most factors relate to individual as well as societal choices and that the societal climate interacts with individual choices to enable or inhibit them. One illustrating point is the notion of the Mediterranean diet, which overtly links eating with culture and geography. Thus, the approach to cardiovascular disease prevention and treatment is characterized by the interplay between individual and society and between clinical and societal factors.¹³ This in turn implies that public health policy has the potential to play a central role in disease prevention.

Some examples of the interaction between public health policy and individual choice include the effect of smoke-free workplaces on smoking behavior¹⁴ and that of providing caloric information in chain restaurants on purchasing behavior.¹⁵ Another example of policy-based interventions is the elimination of trans fats from restaurant cooking.¹⁶ Some have argued that policy-based interventions represent undue governmental involvement in individual choices. However, the decisions made decades ago to promote smoking or to process foods in such a way as to make certain aspects of cardiovascular disease a food-borne illness were hardly implemented with the goal of individual empowerment. Indeed, there is an element of societal disingenuity to require of individuals personal choices that oppose societal trends.

At this point, the national cost of treating cardiovascular diseases cannot be sustained, and prevention is urgent. Because prevention can benefit from policies aimed at creating a healthier environment, this approach must be expanded, with obvious targets being school-based meals provided to children, which still do not meet national dietary recommendations for good health,¹⁷ and the conceptualization and restructuring of the environment to promote physical activity. These and other public health measures should be envisioned as complementary and synergistic with clinical care, because unhealthy societal choices that lead to illness result in unsustainable strain on health care systems.

The studies by Forman et al³ and Djoussé et al⁴ underscore that healthy lifestyle will help prevent cardiovascular disease and greatly enhance health, which is a compelling reminder that health is the shared responsibility of individuals and communities. This in turn implies that public health policies and clinical care must join forces to achieve effective disease prevention.