Healthy Populations Nurture Healthy People

The fall 2004 decision by NBC to introduce a new TV program dramatizing the fight against emerging disease threats might be taken as a sign of rising glamour for the public health professions. Modeled on the successful format of ratings winners such as ER and CSI, the series Medical Investigation features a cast of young, dashing, and sometimes overbearing personalities devoted to saving lives and unraveling mysteries, all while spouting a steady stream of technical jargon as they combat threats ranging from “Blue Man” syndrome to Legionnaire’s disease.

If the series departs in some measure from the primary-care domain of ER (and predecessors ranging from St. Elsewhere to M.A.S.H.), its emphasis on acute crisis intervention will come as little surprise to public health professionals long accustomed to the fact that the general public rarely associates their work with life-saving drama, much less pulsepounding heroics. In real life, a cardiac surgeon may have many opportunities to experience the gratitude of patients after a successful triple-bypass surgery. However, it would be an unusual event indeed if patients sought out and thanked the elected official whose leadership on antismoking laws, the city planner whose design of pedestrian-friendly neighborhoods, or the health plan administrator whose enforcement of quality standards for treating high blood pressure or cholesterol levels might have obviated the need for acute cardiac care in the first place—and at far less expense and discomfort to the patient.

Our difficulty in conceptualizing the achievements of avoided risks, as compared to the defeat of realized illnesses, is reflected in the pattern of expenditures devoted to health care in the United States. For example, it is estimated that roughly 95 percent of national health expenditures are devoted to direct care services and related research, leaving only 5 percent for population health activities. Although the magnitude of the direct care expenditures explains some of the remarkable successes of biomedical research and advances in clinical care, public health officials are quick to point out that roughly 70 percent of avoidable mortality in the United States results from behavioral, social, and environmental factors that are potentially modifiable through preventive health measures.

Moreover, one can argue that the results of this disjunction are readily apparent in the poor standing of the United States relative to other industrialized nations in many leading health indicators. Recent rankings of countries that participate in the Organisation for Economic Co-operation and Development (OECD) place the United States below the OECD mean in life expectancy, 28th among a group of 39 industrialized nations in infant mortality, and highest among a group of 30 industrialized nations in cancer incidence. Rates of other chronic diseases are also on the rise in the United States, and the country lags behind most other industrialized nations in making health care available equitably to all. Small wonder then that the Institute of Medicine’s 2003 report The Future of the Public’s Health concluded that “the nation’s heavy investment in the personal health care system is a limited future strategy for promoting health.”

The need to allocate resources more effectively to preventive as well as curative health care efforts is only one element of a broader need to reconceptualize public health strategies as a whole. A further issue is the fact that when many people think of the public health profession, they are most likely to conjure up solely images of either vaccination programs or their (frequently understaffed) county and local public health departments. Both of these institutions are indeed part of a venerable lineage dating back to the major 19th-century sanitation and public health campaigns and their successors, which have provided health benefits across many generations. However, to build a maximally effective public health strategy for the future, we must move toward broader population perspectives on health.

What is population health?

At its core, the notion of population health is that sustained health improvement for individuals can often be accomplished only through efforts aimed at groups— that is, environmental, educational, organizational, social, or policy interventions that produce population-wide effects. Further, relatively small changes for individuals can often yield dramatic changes in disease incidence across the entire population.

The idea of population health recognizes that disease risk consists largely of a continuum across populations rather than a simple dichotomy between high-risk and low-risk individuals. There is simply no clear division between being at risk or not at risk of disease with regard to factors such as cholesterol levels, blood pressure, diet and physical activity, exposure to toxic substances, stress, and a wide range of other social and environmental conditions. Moreover, most commonly only a relatively small percentage of the population will fall at the extremes of either high or low risk. For this reason, the path toward achieving the greatest benefits within a population will often involve attempts to lower the distribution of risk for the population as a whole rather than simply targeting individuals or high-risk groups. Well-known examples of this approach include the fluoridation of water, seatbelt laws, the elimination of leaded gasoline, the regulation of residential hot water boilers to avoid scalding injuries, air quality standards, laws that concern the isolation and quarantine of infectious individuals, or laws that protect the public from unsafe foods and drugs or set standards for diet in public schools.

A major component of such an understanding is that an individual’s risk must be framed within the context of the larger community. Rather than simply asking why a particular individual has suffered illness or premature death, we must ask why a population includes its distinctive constellation of higher and lower risks in different areas. By understanding this composite structure, one can design an array of disease prevention and health promotion strategies that can improve the long-term health outcomes of the overall population rather than reacting only to the acute care needs of individuals after they have become ill. Improvements in children’s health, in particular, can reduce the need for costly treatments later in life for illnesses that can be prevented by health-promotion interventions. Similarly, prevention programs can be targeted to address risk factors in specific populations. For example, lifestyle changes to prevent diabetes in African-American and Hispanic communities, where rates of this disease are far higher than in the general population.

This vision guides the Healthy People 2010 initiative that is led by the U.S. Department of Health and Human Services. Like its predecessor Healthy People 2000, the initiative encompasses an overall strategy for preventing disease and improving health outcomes in a range of target areas across the nation. Similar efforts have been initiated by the World Health Organization and a number of governments.

A broader vision

Achieving substantial progress in population health requires far more than engaging only the health-related sectors of government and society. Creating healthier societies requires understanding the “social determinants of health”: the aspects of national, community, and family life that support or undermine health. Improvements in the social factors that influence health requires involvement of all sectors: education, transportation, labor conditions, agriculture, environmental protection, and of course, public health. Strategies must involve not only horizontal coordination across government sectors but vertical coordination from federal to state and local levels, and engagement with nongovernmental sectors such as business, the media, academia, and all segments of the health care delivery system.

A population approach will continue to be needed for adapting to the country’s future health care needs. For example, the graying of the U.S. population—with the over-65 population projected to reach 13.3 percent in 2010 and 18.5 percent by 2025—will bring with it an increasedneed for effective strategies and services to promote healthy aging. We will continue to need robust systems of surveillance and analysis at national and local levels, not to mention commitments that in times of budgetary crisis, preventive and population health measures will not be the first to fall to cuts in discretionary spending simply because they are more anonymous than cuts in direct care services.

Taking a population perspective does not mean adopting an either/or dichotomy between population and individual health needs or abandoning acute care for sick individuals in favor of preventive care for populations. Indeed, a final element of population health improvement that merits discussion is the application of population perspectives to the primary care system, as exemplified in the quality movement. First brought to wide attention by the Institute of Medicine’s report To Err is Human, the quality movement extends to efforts to develop and implement system-wide improvements that would eliminate or ameliorate below-standard care practices in numerous areas. A recent study by the RAND Corporation’s Elizabeth McGlynn and colleagues found that across 12 U.S. metropolitan areas, only about 55 percent of individuals received the recommended standard of acute, chronic, and preventive care. In its 2004 annual report, the National Commission on Quality Assurance concluded that substandard care resulted in between 42,000 and 79,000 premature deaths, as well as nearly $2 billion in extra hospital costs, each year.

A comprehensive vision of population health thus will encompass not only the social conditions that affect the health of all people but also the systems that deliver individual medical care. We need to see improvements across all aspects of population health. The articles that follow reflect the variety of fronts on which progress is possible, from the intricacies of the human genome to the structure of the legal system.